before send to remote

env/lib/python3.8/site-packages/django/db/models/fields/files.py

@@ -0,0 +1,509 @@
+import datetime
+import posixpath
+
+from django import forms
+from django.core import checks
+from django.core.files.base import File
+from django.core.files.images import ImageFile
+from django.core.files.storage import Storage, default_storage
+from django.core.files.utils import validate_file_name
+from django.db.models import signals
+from django.db.models.fields import Field
+from django.db.models.query_utils import DeferredAttribute
+from django.utils.translation import gettext_lazy as _
+
+
+class FieldFile(File):
+    def __init__(self, instance, field, name):
+        super().__init__(None, name)
+        self.instance = instance
+        self.field = field
+        self.storage = field.storage
+        self._committed = True
+
+    def __eq__(self, other):
+        # Older code may be expecting FileField values to be simple strings.
+        # By overriding the == operator, it can remain backwards compatibility.
+        if hasattr(other, "name"):
+            return self.name == other.name
+        return self.name == other
+
+    def __hash__(self):
+        return hash(self.name)
+
+    # The standard File contains most of the necessary properties, but
+    # FieldFiles can be instantiated without a name, so that needs to
+    # be checked for here.
+
+    def _require_file(self):
+        if not self:
+            raise ValueError(
+                "The '%s' attribute has no file associated with it." % self.field.name
+            )
+
+    def _get_file(self):
+        self._require_file()
+        if getattr(self, "_file", None) is None:
+            self._file = self.storage.open(self.name, "rb")
+        return self._file
+
+    def _set_file(self, file):
+        self._file = file
+
+    def _del_file(self):
+        del self._file
+
+    file = property(_get_file, _set_file, _del_file)
+
+    @property
+    def path(self):
+        self._require_file()
+        return self.storage.path(self.name)
+
+    @property
+    def url(self):
+        self._require_file()
+        return self.storage.url(self.name)
+
+    @property
+    def size(self):
+        self._require_file()
+        if not self._committed:
+            return self.file.size
+        return self.storage.size(self.name)
+
+    def open(self, mode="rb"):
+        self._require_file()
+        if getattr(self, "_file", None) is None:
+            self.file = self.storage.open(self.name, mode)
+        else:
+            self.file.open(mode)
+        return self
+
+    # open() doesn't alter the file's contents, but it does reset the pointer
+    open.alters_data = True
+
+    # In addition to the standard File API, FieldFiles have extra methods
+    # to further manipulate the underlying file, as well as update the
+    # associated model instance.
+
+    def save(self, name, content, save=True):
+        name = self.field.generate_filename(self.instance, name)
+        self.name = self.storage.save(name, content, max_length=self.field.max_length)
+        setattr(self.instance, self.field.attname, self.name)
+        self._committed = True
+
+        # Save the object because it has changed, unless save is False
+        if save:
+            self.instance.save()
+
+    save.alters_data = True
+
+    def delete(self, save=True):
+        if not self:
+            return
+        # Only close the file if it's already open, which we know by the
+        # presence of self._file
+        if hasattr(self, "_file"):
+            self.close()
+            del self.file
+
+        self.storage.delete(self.name)
+
+        self.name = None
+        setattr(self.instance, self.field.attname, self.name)
+        self._committed = False
+
+        if save:
+            self.instance.save()
+
+    delete.alters_data = True
+
+    @property
+    def closed(self):
+        file = getattr(self, "_file", None)
+        return file is None or file.closed
+
+    def close(self):
+        file = getattr(self, "_file", None)
+        if file is not None:
+            file.close()
+
+    def __getstate__(self):
+        # FieldFile needs access to its associated model field, an instance and
+        # the file's name. Everything else will be restored later, by
+        # FileDescriptor below.
+        return {
+            "name": self.name,
+            "closed": False,
+            "_committed": True,
+            "_file": None,
+            "instance": self.instance,
+            "field": self.field,
+        }
+
+    def __setstate__(self, state):
+        self.__dict__.update(state)
+        self.storage = self.field.storage
+
+
+class FileDescriptor(DeferredAttribute):
+    """
+    The descriptor for the file attribute on the model instance. Return a
+    FieldFile when accessed so you can write code like::
+
+        >>> from myapp.models import MyModel
+        >>> instance = MyModel.objects.get(pk=1)
+        >>> instance.file.size
+
+    Assign a file object on assignment so you can do::
+
+        >>> with open('/path/to/hello.world') as f:
+        ...     instance.file = File(f)
+    """
+
+    def __get__(self, instance, cls=None):
+        if instance is None:
+            return self
+
+        # This is slightly complicated, so worth an explanation.
+        # instance.file`needs to ultimately return some instance of `File`,
+        # probably a subclass. Additionally, this returned object needs to have
+        # the FieldFile API so that users can easily do things like
+        # instance.file.path and have that delegated to the file storage engine.
+        # Easy enough if we're strict about assignment in __set__, but if you
+        # peek below you can see that we're not. So depending on the current
+        # value of the field we have to dynamically construct some sort of
+        # "thing" to return.
+
+        # The instance dict contains whatever was originally assigned
+        # in __set__.
+        file = super().__get__(instance, cls)
+
+        # If this value is a string (instance.file = "path/to/file") or None
+        # then we simply wrap it with the appropriate attribute class according
+        # to the file field. [This is FieldFile for FileFields and
+        # ImageFieldFile for ImageFields; it's also conceivable that user
+        # subclasses might also want to subclass the attribute class]. This
+        # object understands how to convert a path to a file, and also how to
+        # handle None.
+        if isinstance(file, str) or file is None:
+            attr = self.field.attr_class(instance, self.field, file)
+            instance.__dict__[self.field.attname] = attr
+
+        # Other types of files may be assigned as well, but they need to have
+        # the FieldFile interface added to them. Thus, we wrap any other type of
+        # File inside a FieldFile (well, the field's attr_class, which is
+        # usually FieldFile).
+        elif isinstance(file, File) and not isinstance(file, FieldFile):
+            file_copy = self.field.attr_class(instance, self.field, file.name)
+            file_copy.file = file
+            file_copy._committed = False
+            instance.__dict__[self.field.attname] = file_copy
+
+        # Finally, because of the (some would say boneheaded) way pickle works,
+        # the underlying FieldFile might not actually itself have an associated
+        # file. So we need to reset the details of the FieldFile in those cases.
+        elif isinstance(file, FieldFile) and not hasattr(file, "field"):
+            file.instance = instance
+            file.field = self.field
+            file.storage = self.field.storage
+
+        # Make sure that the instance is correct.
+        elif isinstance(file, FieldFile) and instance is not file.instance:
+            file.instance = instance
+
+        # That was fun, wasn't it?
+        return instance.__dict__[self.field.attname]
+
+    def __set__(self, instance, value):
+        instance.__dict__[self.field.attname] = value
+
+
+class FileField(Field):
+
+    # The class to wrap instance attributes in. Accessing the file object off
+    # the instance will always return an instance of attr_class.
+    attr_class = FieldFile
+
+    # The descriptor to use for accessing the attribute off of the class.
+    descriptor_class = FileDescriptor
+
+    description = _("File")
+
+    def __init__(
+        self, verbose_name=None, name=None, upload_to="", storage=None, **kwargs
+    ):
+        self._primary_key_set_explicitly = "primary_key" in kwargs
+
+        self.storage = storage or default_storage
+        if callable(self.storage):
+            # Hold a reference to the callable for deconstruct().
+            self._storage_callable = self.storage
+            self.storage = self.storage()
+            if not isinstance(self.storage, Storage):
+                raise TypeError(
+                    "%s.storage must be a subclass/instance of %s.%s"
+                    % (
+                        self.__class__.__qualname__,
+                        Storage.__module__,
+                        Storage.__qualname__,
+                    )
+                )
+        self.upload_to = upload_to
+
+        kwargs.setdefault("max_length", 100)
+        super().__init__(verbose_name, name, **kwargs)
+
+    def check(self, **kwargs):
+        return [
+            *super().check(**kwargs),
+            *self._check_primary_key(),
+            *self._check_upload_to(),
+        ]
+
+    def _check_primary_key(self):
+        if self._primary_key_set_explicitly:
+            return [
+                checks.Error(
+                    "'primary_key' is not a valid argument for a %s."
+                    % self.__class__.__name__,
+                    obj=self,
+                    id="fields.E201",
+                )
+            ]
+        else:
+            return []
+
+    def _check_upload_to(self):
+        if isinstance(self.upload_to, str) and self.upload_to.startswith("/"):
+            return [
+                checks.Error(
+                    "%s's 'upload_to' argument must be a relative path, not an "
+                    "absolute path." % self.__class__.__name__,
+                    obj=self,
+                    id="fields.E202",
+                    hint="Remove the leading slash.",
+                )
+            ]
+        else:
+            return []
+
+    def deconstruct(self):
+        name, path, args, kwargs = super().deconstruct()
+        if kwargs.get("max_length") == 100:
+            del kwargs["max_length"]
+        kwargs["upload_to"] = self.upload_to
+        if self.storage is not default_storage:
+            kwargs["storage"] = getattr(self, "_storage_callable", self.storage)
+        return name, path, args, kwargs
+
+    def get_internal_type(self):
+        return "FileField"
+
+    def get_prep_value(self, value):
+        value = super().get_prep_value(value)
+        # Need to convert File objects provided via a form to string for
+        # database insertion.
+        if value is None:
+            return None
+        return str(value)
+
+    def pre_save(self, model_instance, add):
+        file = super().pre_save(model_instance, add)
+        if file and not file._committed:
+            # Commit the file to storage prior to saving the model
+            file.save(file.name, file.file, save=False)
+        return file
+
+    def contribute_to_class(self, cls, name, **kwargs):
+        super().contribute_to_class(cls, name, **kwargs)
+        setattr(cls, self.attname, self.descriptor_class(self))
+
+    def generate_filename(self, instance, filename):
+        """
+        Apply (if callable) or prepend (if a string) upload_to to the filename,
+        then delegate further processing of the name to the storage backend.
+        Until the storage layer, all file paths are expected to be Unix style
+        (with forward slashes).
+        """
+        if callable(self.upload_to):
+            filename = self.upload_to(instance, filename)
+        else:
+            dirname = datetime.datetime.now().strftime(str(self.upload_to))
+            filename = posixpath.join(dirname, filename)
+        filename = validate_file_name(filename, allow_relative_path=True)
+        return self.storage.generate_filename(filename)
+
+    def save_form_data(self, instance, data):
+        # Important: None means "no change", other false value means "clear"
+        # This subtle distinction (rather than a more explicit marker) is
+        # needed because we need to consume values that are also sane for a
+        # regular (non Model-) Form to find in its cleaned_data dictionary.
+        if data is not None:
+            # This value will be converted to str and stored in the
+            # database, so leaving False as-is is not acceptable.
+            setattr(instance, self.name, data or "")
+
+    def formfield(self, **kwargs):
+        return super().formfield(
+            **{
+                "form_class": forms.FileField,
+                "max_length": self.max_length,
+                **kwargs,
+            }
+        )
+
+
+class ImageFileDescriptor(FileDescriptor):
+    """
+    Just like the FileDescriptor, but for ImageFields. The only difference is
+    assigning the width/height to the width_field/height_field, if appropriate.
+    """
+
+    def __set__(self, instance, value):
+        previous_file = instance.__dict__.get(self.field.attname)
+        super().__set__(instance, value)
+
+        # To prevent recalculating image dimensions when we are instantiating
+        # an object from the database (bug #11084), only update dimensions if
+        # the field had a value before this assignment.  Since the default
+        # value for FileField subclasses is an instance of field.attr_class,
+        # previous_file will only be None when we are called from
+        # Model.__init__().  The ImageField.update_dimension_fields method
+        # hooked up to the post_init signal handles the Model.__init__() cases.
+        # Assignment happening outside of Model.__init__() will trigger the
+        # update right here.
+        if previous_file is not None:
+            self.field.update_dimension_fields(instance, force=True)
+
+
+class ImageFieldFile(ImageFile, FieldFile):
+    def delete(self, save=True):
+        # Clear the image dimensions cache
+        if hasattr(self, "_dimensions_cache"):
+            del self._dimensions_cache
+        super().delete(save)
+
+
+class ImageField(FileField):
+    attr_class = ImageFieldFile
+    descriptor_class = ImageFileDescriptor
+    description = _("Image")
+
+    def __init__(
+        self,
+        verbose_name=None,
+        name=None,
+        width_field=None,
+        height_field=None,
+        **kwargs,
+    ):
+        self.width_field, self.height_field = width_field, height_field
+        super().__init__(verbose_name, name, **kwargs)
+
+    def check(self, **kwargs):
+        return [
+            *super().check(**kwargs),
+            *self._check_image_library_installed(),
+        ]
+
+    def _check_image_library_installed(self):
+        try:
+            from PIL import Image  # NOQA
+        except ImportError:
+            return [
+                checks.Error(
+                    "Cannot use ImageField because Pillow is not installed.",
+                    hint=(
+                        "Get Pillow at https://pypi.org/project/Pillow/ "
+                        'or run command "python -m pip install Pillow".'
+                    ),
+                    obj=self,
+                    id="fields.E210",
+                )
+            ]
+        else:
+            return []
+
+    def deconstruct(self):
+        name, path, args, kwargs = super().deconstruct()
+        if self.width_field:
+            kwargs["width_field"] = self.width_field
+        if self.height_field:
+            kwargs["height_field"] = self.height_field
+        return name, path, args, kwargs
+
+    def contribute_to_class(self, cls, name, **kwargs):
+        super().contribute_to_class(cls, name, **kwargs)
+        # Attach update_dimension_fields so that dimension fields declared
+        # after their corresponding image field don't stay cleared by
+        # Model.__init__, see bug #11196.
+        # Only run post-initialization dimension update on non-abstract models
+        if not cls._meta.abstract:
+            signals.post_init.connect(self.update_dimension_fields, sender=cls)
+
+    def update_dimension_fields(self, instance, force=False, *args, **kwargs):
+        """
+        Update field's width and height fields, if defined.
+
+        This method is hooked up to model's post_init signal to update
+        dimensions after instantiating a model instance.  However, dimensions
+        won't be updated if the dimensions fields are already populated.  This
+        avoids unnecessary recalculation when loading an object from the
+        database.
+
+        Dimensions can be forced to update with force=True, which is how
+        ImageFileDescriptor.__set__ calls this method.
+        """
+        # Nothing to update if the field doesn't have dimension fields or if
+        # the field is deferred.
+        has_dimension_fields = self.width_field or self.height_field
+        if not has_dimension_fields or self.attname not in instance.__dict__:
+            return
+
+        # getattr will call the ImageFileDescriptor's __get__ method, which
+        # coerces the assigned value into an instance of self.attr_class
+        # (ImageFieldFile in this case).
+        file = getattr(instance, self.attname)
+
+        # Nothing to update if we have no file and not being forced to update.
+        if not file and not force:
+            return
+
+        dimension_fields_filled = not (
+            (self.width_field and not getattr(instance, self.width_field))
+            or (self.height_field and not getattr(instance, self.height_field))
+        )
+        # When both dimension fields have values, we are most likely loading
+        # data from the database or updating an image field that already had
+        # an image stored.  In the first case, we don't want to update the
+        # dimension fields because we are already getting their values from the
+        # database.  In the second case, we do want to update the dimensions
+        # fields and will skip this return because force will be True since we
+        # were called from ImageFileDescriptor.__set__.
+        if dimension_fields_filled and not force:
+            return
+
+        # file should be an instance of ImageFieldFile or should be None.
+        if file:
+            width = file.width
+            height = file.height
+        else:
+            # No file, so clear dimensions fields.
+            width = None
+            height = None
+
+        # Update the width and height fields.
+        if self.width_field:
+            setattr(instance, self.width_field, width)
+        if self.height_field:
+            setattr(instance, self.height_field, height)
+
+    def formfield(self, **kwargs):
+        return super().formfield(
+            **{
+                "form_class": forms.ImageField,
+                **kwargs,
+            }
+        )

env/lib/python3.8/site-packages/django/db/models/fields/json.py

@@ -0,0 +1,575 @@
+import json
+
+from django import forms
+from django.core import checks, exceptions
+from django.db import NotSupportedError, connections, router
+from django.db.models import lookups
+from django.db.models.lookups import PostgresOperatorLookup, Transform
+from django.utils.translation import gettext_lazy as _
+
+from . import Field
+from .mixins import CheckFieldDefaultMixin
+
+__all__ = ["JSONField"]
+
+
+class JSONField(CheckFieldDefaultMixin, Field):
+    empty_strings_allowed = False
+    description = _("A JSON object")
+    default_error_messages = {
+        "invalid": _("Value must be valid JSON."),
+    }
+    _default_hint = ("dict", "{}")
+
+    def __init__(
+        self,
+        verbose_name=None,
+        name=None,
+        encoder=None,
+        decoder=None,
+        **kwargs,
+    ):
+        if encoder and not callable(encoder):
+            raise ValueError("The encoder parameter must be a callable object.")
+        if decoder and not callable(decoder):
+            raise ValueError("The decoder parameter must be a callable object.")
+        self.encoder = encoder
+        self.decoder = decoder
+        super().__init__(verbose_name, name, **kwargs)
+
+    def check(self, **kwargs):
+        errors = super().check(**kwargs)
+        databases = kwargs.get("databases") or []
+        errors.extend(self._check_supported(databases))
+        return errors
+
+    def _check_supported(self, databases):
+        errors = []
+        for db in databases:
+            if not router.allow_migrate_model(db, self.model):
+                continue
+            connection = connections[db]
+            if (
+                self.model._meta.required_db_vendor
+                and self.model._meta.required_db_vendor != connection.vendor
+            ):
+                continue
+            if not (
+                "supports_json_field" in self.model._meta.required_db_features
+                or connection.features.supports_json_field
+            ):
+                errors.append(
+                    checks.Error(
+                        "%s does not support JSONFields." % connection.display_name,
+                        obj=self.model,
+                        id="fields.E180",
+                    )
+                )
+        return errors
+
+    def deconstruct(self):
+        name, path, args, kwargs = super().deconstruct()
+        if self.encoder is not None:
+            kwargs["encoder"] = self.encoder
+        if self.decoder is not None:
+            kwargs["decoder"] = self.decoder
+        return name, path, args, kwargs
+
+    def from_db_value(self, value, expression, connection):
+        if value is None:
+            return value
+        # Some backends (SQLite at least) extract non-string values in their
+        # SQL datatypes.
+        if isinstance(expression, KeyTransform) and not isinstance(value, str):
+            return value
+        try:
+            return json.loads(value, cls=self.decoder)
+        except json.JSONDecodeError:
+            return value
+
+    def get_internal_type(self):
+        return "JSONField"
+
+    def get_prep_value(self, value):
+        if value is None:
+            return value
+        return json.dumps(value, cls=self.encoder)
+
+    def get_transform(self, name):
+        transform = super().get_transform(name)
+        if transform:
+            return transform
+        return KeyTransformFactory(name)
+
+    def validate(self, value, model_instance):
+        super().validate(value, model_instance)
+        try:
+            json.dumps(value, cls=self.encoder)
+        except TypeError:
+            raise exceptions.ValidationError(
+                self.error_messages["invalid"],
+                code="invalid",
+                params={"value": value},
+            )
+
+    def value_to_string(self, obj):
+        return self.value_from_object(obj)
+
+    def formfield(self, **kwargs):
+        return super().formfield(
+            **{
+                "form_class": forms.JSONField,
+                "encoder": self.encoder,
+                "decoder": self.decoder,
+                **kwargs,
+            }
+        )
+
+
+def compile_json_path(key_transforms, include_root=True):
+    path = ["$"] if include_root else []
+    for key_transform in key_transforms:
+        try:
+            num = int(key_transform)
+        except ValueError:  # non-integer
+            path.append(".")
+            path.append(json.dumps(key_transform))
+        else:
+            path.append("[%s]" % num)
+    return "".join(path)
+
+
+class DataContains(PostgresOperatorLookup):
+    lookup_name = "contains"
+    postgres_operator = "@>"
+
+    def as_sql(self, compiler, connection):
+        if not connection.features.supports_json_field_contains:
+            raise NotSupportedError(
+                "contains lookup is not supported on this database backend."
+            )
+        lhs, lhs_params = self.process_lhs(compiler, connection)
+        rhs, rhs_params = self.process_rhs(compiler, connection)
+        params = tuple(lhs_params) + tuple(rhs_params)
+        return "JSON_CONTAINS(%s, %s)" % (lhs, rhs), params
+
+
+class ContainedBy(PostgresOperatorLookup):
+    lookup_name = "contained_by"
+    postgres_operator = "<@"
+
+    def as_sql(self, compiler, connection):
+        if not connection.features.supports_json_field_contains:
+            raise NotSupportedError(
+                "contained_by lookup is not supported on this database backend."
+            )
+        lhs, lhs_params = self.process_lhs(compiler, connection)
+        rhs, rhs_params = self.process_rhs(compiler, connection)
+        params = tuple(rhs_params) + tuple(lhs_params)
+        return "JSON_CONTAINS(%s, %s)" % (rhs, lhs), params
+
+
+class HasKeyLookup(PostgresOperatorLookup):
+    logical_operator = None
+
+    def compile_json_path_final_key(self, key_transform):
+        # Compile the final key without interpreting ints as array elements.
+        return ".%s" % json.dumps(key_transform)
+
+    def as_sql(self, compiler, connection, template=None):
+        # Process JSON path from the left-hand side.
+        if isinstance(self.lhs, KeyTransform):
+            lhs, lhs_params, lhs_key_transforms = self.lhs.preprocess_lhs(
+                compiler, connection
+            )
+            lhs_json_path = compile_json_path(lhs_key_transforms)
+        else:
+            lhs, lhs_params = self.process_lhs(compiler, connection)
+            lhs_json_path = "$"
+        sql = template % lhs
+        # Process JSON path from the right-hand side.
+        rhs = self.rhs
+        rhs_params = []
+        if not isinstance(rhs, (list, tuple)):
+            rhs = [rhs]
+        for key in rhs:
+            if isinstance(key, KeyTransform):
+                *_, rhs_key_transforms = key.preprocess_lhs(compiler, connection)
+            else:
+                rhs_key_transforms = [key]
+            *rhs_key_transforms, final_key = rhs_key_transforms
+            rhs_json_path = compile_json_path(rhs_key_transforms, include_root=False)
+            rhs_json_path += self.compile_json_path_final_key(final_key)
+            rhs_params.append(lhs_json_path + rhs_json_path)
+        # Add condition for each key.
+        if self.logical_operator:
+            sql = "(%s)" % self.logical_operator.join([sql] * len(rhs_params))
+        return sql, tuple(lhs_params) + tuple(rhs_params)
+
+    def as_mysql(self, compiler, connection):
+        return self.as_sql(
+            compiler, connection, template="JSON_CONTAINS_PATH(%s, 'one', %%s)"
+        )
+
+    def as_oracle(self, compiler, connection):
+        sql, params = self.as_sql(
+            compiler, connection, template="JSON_EXISTS(%s, '%%s')"
+        )
+        # Add paths directly into SQL because path expressions cannot be passed
+        # as bind variables on Oracle.
+        return sql % tuple(params), []
+
+    def as_postgresql(self, compiler, connection):
+        if isinstance(self.rhs, KeyTransform):
+            *_, rhs_key_transforms = self.rhs.preprocess_lhs(compiler, connection)
+            for key in rhs_key_transforms[:-1]:
+                self.lhs = KeyTransform(key, self.lhs)
+            self.rhs = rhs_key_transforms[-1]
+        return super().as_postgresql(compiler, connection)
+
+    def as_sqlite(self, compiler, connection):
+        return self.as_sql(
+            compiler, connection, template="JSON_TYPE(%s, %%s) IS NOT NULL"
+        )
+
+
+class HasKey(HasKeyLookup):
+    lookup_name = "has_key"
+    postgres_operator = "?"
+    prepare_rhs = False
+
+
+class HasKeys(HasKeyLookup):
+    lookup_name = "has_keys"
+    postgres_operator = "?&"
+    logical_operator = " AND "
+
+    def get_prep_lookup(self):
+        return [str(item) for item in self.rhs]
+
+
+class HasAnyKeys(HasKeys):
+    lookup_name = "has_any_keys"
+    postgres_operator = "?|"
+    logical_operator = " OR "
+
+
+class HasKeyOrArrayIndex(HasKey):
+    def compile_json_path_final_key(self, key_transform):
+        return compile_json_path([key_transform], include_root=False)
+
+
+class CaseInsensitiveMixin:
+    """
+    Mixin to allow case-insensitive comparison of JSON values on MySQL.
+    MySQL handles strings used in JSON context using the utf8mb4_bin collation.
+    Because utf8mb4_bin is a binary collation, comparison of JSON values is
+    case-sensitive.
+    """
+
+    def process_lhs(self, compiler, connection):
+        lhs, lhs_params = super().process_lhs(compiler, connection)
+        if connection.vendor == "mysql":
+            return "LOWER(%s)" % lhs, lhs_params
+        return lhs, lhs_params
+
+    def process_rhs(self, compiler, connection):
+        rhs, rhs_params = super().process_rhs(compiler, connection)
+        if connection.vendor == "mysql":
+            return "LOWER(%s)" % rhs, rhs_params
+        return rhs, rhs_params
+
+
+class JSONExact(lookups.Exact):
+    can_use_none_as_rhs = True
+
+    def process_rhs(self, compiler, connection):
+        rhs, rhs_params = super().process_rhs(compiler, connection)
+        # Treat None lookup values as null.
+        if rhs == "%s" and rhs_params == [None]:
+            rhs_params = ["null"]
+        if connection.vendor == "mysql":
+            func = ["JSON_EXTRACT(%s, '$')"] * len(rhs_params)
+            rhs = rhs % tuple(func)
+        return rhs, rhs_params
+
+
+class JSONIContains(CaseInsensitiveMixin, lookups.IContains):
+    pass
+
+
+JSONField.register_lookup(DataContains)
+JSONField.register_lookup(ContainedBy)
+JSONField.register_lookup(HasKey)
+JSONField.register_lookup(HasKeys)
+JSONField.register_lookup(HasAnyKeys)
+JSONField.register_lookup(JSONExact)
+JSONField.register_lookup(JSONIContains)
+
+
+class KeyTransform(Transform):
+    postgres_operator = "->"
+    postgres_nested_operator = "#>"
+
+    def __init__(self, key_name, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+        self.key_name = str(key_name)
+
+    def preprocess_lhs(self, compiler, connection):
+        key_transforms = [self.key_name]
+        previous = self.lhs
+        while isinstance(previous, KeyTransform):
+            key_transforms.insert(0, previous.key_name)
+            previous = previous.lhs
+        lhs, params = compiler.compile(previous)
+        if connection.vendor == "oracle":
+            # Escape string-formatting.
+            key_transforms = [key.replace("%", "%%") for key in key_transforms]
+        return lhs, params, key_transforms
+
+    def as_mysql(self, compiler, connection):
+        lhs, params, key_transforms = self.preprocess_lhs(compiler, connection)
+        json_path = compile_json_path(key_transforms)
+        return "JSON_EXTRACT(%s, %%s)" % lhs, tuple(params) + (json_path,)
+
+    def as_oracle(self, compiler, connection):
+        lhs, params, key_transforms = self.preprocess_lhs(compiler, connection)
+        json_path = compile_json_path(key_transforms)
+        return (
+            "COALESCE(JSON_QUERY(%s, '%s'), JSON_VALUE(%s, '%s'))"
+            % ((lhs, json_path) * 2)
+        ), tuple(params) * 2
+
+    def as_postgresql(self, compiler, connection):
+        lhs, params, key_transforms = self.preprocess_lhs(compiler, connection)
+        if len(key_transforms) > 1:
+            sql = "(%s %s %%s)" % (lhs, self.postgres_nested_operator)
+            return sql, tuple(params) + (key_transforms,)
+        try:
+            lookup = int(self.key_name)
+        except ValueError:
+            lookup = self.key_name
+        return "(%s %s %%s)" % (lhs, self.postgres_operator), tuple(params) + (lookup,)
+
+    def as_sqlite(self, compiler, connection):
+        lhs, params, key_transforms = self.preprocess_lhs(compiler, connection)
+        json_path = compile_json_path(key_transforms)
+        datatype_values = ",".join(
+            [repr(datatype) for datatype in connection.ops.jsonfield_datatype_values]
+        )
+        return (
+            "(CASE WHEN JSON_TYPE(%s, %%s) IN (%s) "
+            "THEN JSON_TYPE(%s, %%s) ELSE JSON_EXTRACT(%s, %%s) END)"
+        ) % (lhs, datatype_values, lhs, lhs), (tuple(params) + (json_path,)) * 3
+
+
+class KeyTextTransform(KeyTransform):
+    postgres_operator = "->>"
+    postgres_nested_operator = "#>>"
+
+
+class KeyTransformTextLookupMixin:
+    """
+    Mixin for combining with a lookup expecting a text lhs from a JSONField
+    key lookup. On PostgreSQL, make use of the ->> operator instead of casting
+    key values to text and performing the lookup on the resulting
+    representation.
+    """
+
+    def __init__(self, key_transform, *args, **kwargs):
+        if not isinstance(key_transform, KeyTransform):
+            raise TypeError(
+                "Transform should be an instance of KeyTransform in order to "
+                "use this lookup."
+            )
+        key_text_transform = KeyTextTransform(
+            key_transform.key_name,
+            *key_transform.source_expressions,
+            **key_transform.extra,
+        )
+        super().__init__(key_text_transform, *args, **kwargs)
+
+
+class KeyTransformIsNull(lookups.IsNull):
+    # key__isnull=False is the same as has_key='key'
+    def as_oracle(self, compiler, connection):
+        sql, params = HasKeyOrArrayIndex(
+            self.lhs.lhs,
+            self.lhs.key_name,
+        ).as_oracle(compiler, connection)
+        if not self.rhs:
+            return sql, params
+        # Column doesn't have a key or IS NULL.
+        lhs, lhs_params, _ = self.lhs.preprocess_lhs(compiler, connection)
+        return "(NOT %s OR %s IS NULL)" % (sql, lhs), tuple(params) + tuple(lhs_params)
+
+    def as_sqlite(self, compiler, connection):
+        template = "JSON_TYPE(%s, %%s) IS NULL"
+        if not self.rhs:
+            template = "JSON_TYPE(%s, %%s) IS NOT NULL"
+        return HasKeyOrArrayIndex(self.lhs.lhs, self.lhs.key_name).as_sql(
+            compiler,
+            connection,
+            template=template,
+        )
+
+
+class KeyTransformIn(lookups.In):
+    def resolve_expression_parameter(self, compiler, connection, sql, param):
+        sql, params = super().resolve_expression_parameter(
+            compiler,
+            connection,
+            sql,
+            param,
+        )
+        if (
+            not hasattr(param, "as_sql")
+            and not connection.features.has_native_json_field
+        ):
+            if connection.vendor == "oracle":
+                value = json.loads(param)
+                sql = "%s(JSON_OBJECT('value' VALUE %%s FORMAT JSON), '$.value')"
+                if isinstance(value, (list, dict)):
+                    sql = sql % "JSON_QUERY"
+                else:
+                    sql = sql % "JSON_VALUE"
+            elif connection.vendor == "mysql" or (
+                connection.vendor == "sqlite"
+                and params[0] not in connection.ops.jsonfield_datatype_values
+            ):
+                sql = "JSON_EXTRACT(%s, '$')"
+        if connection.vendor == "mysql" and connection.mysql_is_mariadb:
+            sql = "JSON_UNQUOTE(%s)" % sql
+        return sql, params
+
+
+class KeyTransformExact(JSONExact):
+    def process_rhs(self, compiler, connection):
+        if isinstance(self.rhs, KeyTransform):
+            return super(lookups.Exact, self).process_rhs(compiler, connection)
+        rhs, rhs_params = super().process_rhs(compiler, connection)
+        if connection.vendor == "oracle":
+            func = []
+            sql = "%s(JSON_OBJECT('value' VALUE %%s FORMAT JSON), '$.value')"
+            for value in rhs_params:
+                value = json.loads(value)
+                if isinstance(value, (list, dict)):
+                    func.append(sql % "JSON_QUERY")
+                else:
+                    func.append(sql % "JSON_VALUE")
+            rhs = rhs % tuple(func)
+        elif connection.vendor == "sqlite":
+            func = []
+            for value in rhs_params:
+                if value in connection.ops.jsonfield_datatype_values:
+                    func.append("%s")
+                else:
+                    func.append("JSON_EXTRACT(%s, '$')")
+            rhs = rhs % tuple(func)
+        return rhs, rhs_params
+
+    def as_oracle(self, compiler, connection):
+        rhs, rhs_params = super().process_rhs(compiler, connection)
+        if rhs_params == ["null"]:
+            # Field has key and it's NULL.
+            has_key_expr = HasKeyOrArrayIndex(self.lhs.lhs, self.lhs.key_name)
+            has_key_sql, has_key_params = has_key_expr.as_oracle(compiler, connection)
+            is_null_expr = self.lhs.get_lookup("isnull")(self.lhs, True)
+            is_null_sql, is_null_params = is_null_expr.as_sql(compiler, connection)
+            return (
+                "%s AND %s" % (has_key_sql, is_null_sql),
+                tuple(has_key_params) + tuple(is_null_params),
+            )
+        return super().as_sql(compiler, connection)
+
+
+class KeyTransformIExact(
+    CaseInsensitiveMixin, KeyTransformTextLookupMixin, lookups.IExact
+):
+    pass
+
+
+class KeyTransformIContains(
+    CaseInsensitiveMixin, KeyTransformTextLookupMixin, lookups.IContains
+):
+    pass
+
+
+class KeyTransformStartsWith(KeyTransformTextLookupMixin, lookups.StartsWith):
+    pass
+
+
+class KeyTransformIStartsWith(
+    CaseInsensitiveMixin, KeyTransformTextLookupMixin, lookups.IStartsWith
+):
+    pass
+
+
+class KeyTransformEndsWith(KeyTransformTextLookupMixin, lookups.EndsWith):
+    pass
+
+
+class KeyTransformIEndsWith(
+    CaseInsensitiveMixin, KeyTransformTextLookupMixin, lookups.IEndsWith
+):
+    pass
+
+
+class KeyTransformRegex(KeyTransformTextLookupMixin, lookups.Regex):
+    pass
+
+
+class KeyTransformIRegex(
+    CaseInsensitiveMixin, KeyTransformTextLookupMixin, lookups.IRegex
+):
+    pass
+
+
+class KeyTransformNumericLookupMixin:
+    def process_rhs(self, compiler, connection):
+        rhs, rhs_params = super().process_rhs(compiler, connection)
+        if not connection.features.has_native_json_field:
+            rhs_params = [json.loads(value) for value in rhs_params]
+        return rhs, rhs_params
+
+
+class KeyTransformLt(KeyTransformNumericLookupMixin, lookups.LessThan):
+    pass
+
+
+class KeyTransformLte(KeyTransformNumericLookupMixin, lookups.LessThanOrEqual):
+    pass
+
+
+class KeyTransformGt(KeyTransformNumericLookupMixin, lookups.GreaterThan):
+    pass
+
+
+class KeyTransformGte(KeyTransformNumericLookupMixin, lookups.GreaterThanOrEqual):
+    pass
+
+
+KeyTransform.register_lookup(KeyTransformIn)
+KeyTransform.register_lookup(KeyTransformExact)
+KeyTransform.register_lookup(KeyTransformIExact)
+KeyTransform.register_lookup(KeyTransformIsNull)
+KeyTransform.register_lookup(KeyTransformIContains)
+KeyTransform.register_lookup(KeyTransformStartsWith)
+KeyTransform.register_lookup(KeyTransformIStartsWith)
+KeyTransform.register_lookup(KeyTransformEndsWith)
+KeyTransform.register_lookup(KeyTransformIEndsWith)
+KeyTransform.register_lookup(KeyTransformRegex)
+KeyTransform.register_lookup(KeyTransformIRegex)
+
+KeyTransform.register_lookup(KeyTransformLt)
+KeyTransform.register_lookup(KeyTransformLte)
+KeyTransform.register_lookup(KeyTransformGt)
+KeyTransform.register_lookup(KeyTransformGte)
+
+
+class KeyTransformFactory:
+    def __init__(self, key_name):
+        self.key_name = key_name
+
+    def __call__(self, *args, **kwargs):
+        return KeyTransform(self.key_name, *args, **kwargs)

env/lib/python3.8/site-packages/django/db/models/fields/mixins.py

@@ -0,0 +1,59 @@
+from django.core import checks
+
+NOT_PROVIDED = object()
+
+
+class FieldCacheMixin:
+    """Provide an API for working with the model's fields value cache."""
+
+    def get_cache_name(self):
+        raise NotImplementedError
+
+    def get_cached_value(self, instance, default=NOT_PROVIDED):
+        cache_name = self.get_cache_name()
+        try:
+            return instance._state.fields_cache[cache_name]
+        except KeyError:
+            if default is NOT_PROVIDED:
+                raise
+            return default
+
+    def is_cached(self, instance):
+        return self.get_cache_name() in instance._state.fields_cache
+
+    def set_cached_value(self, instance, value):
+        instance._state.fields_cache[self.get_cache_name()] = value
+
+    def delete_cached_value(self, instance):
+        del instance._state.fields_cache[self.get_cache_name()]
+
+
+class CheckFieldDefaultMixin:
+    _default_hint = ("<valid default>", "<invalid default>")
+
+    def _check_default(self):
+        if (
+            self.has_default()
+            and self.default is not None
+            and not callable(self.default)
+        ):
+            return [
+                checks.Warning(
+                    "%s default should be a callable instead of an instance "
+                    "so that it's not shared between all field instances."
+                    % (self.__class__.__name__,),
+                    hint=(
+                        "Use a callable instead, e.g., use `%s` instead of "
+                        "`%s`." % self._default_hint
+                    ),
+                    obj=self,
+                    id="fields.E010",
+                )
+            ]
+        else:
+            return []
+
+    def check(self, **kwargs):
+        errors = super().check(**kwargs)
+        errors.extend(self._check_default())
+        return errors

env/lib/python3.8/site-packages/django/db/models/fields/proxy.py

@@ -0,0 +1,18 @@
+"""
+Field-like classes that aren't really fields. It's easier to use objects that
+have the same attributes as fields sometimes (avoids a lot of special casing).
+"""
+
+from django.db.models import fields
+
+
+class OrderWrt(fields.IntegerField):
+    """
+    A proxy for the _order database field that is used when
+    Meta.order_with_respect_to is specified.
+    """
+
+    def __init__(self, *args, **kwargs):
+        kwargs["name"] = "_order"
+        kwargs["editable"] = False
+        super().__init__(*args, **kwargs)

env/lib/python3.8/site-packages/django/db/models/fields/related_lookups.py

@@ -0,0 +1,209 @@
+import warnings
+
+from django.db.models.lookups import (
+    Exact,
+    GreaterThan,
+    GreaterThanOrEqual,
+    In,
+    IsNull,
+    LessThan,
+    LessThanOrEqual,
+)
+from django.utils.deprecation import RemovedInDjango50Warning
+
+
+class MultiColSource:
+    contains_aggregate = False
+
+    def __init__(self, alias, targets, sources, field):
+        self.targets, self.sources, self.field, self.alias = (
+            targets,
+            sources,
+            field,
+            alias,
+        )
+        self.output_field = self.field
+
+    def __repr__(self):
+        return "{}({}, {})".format(self.__class__.__name__, self.alias, self.field)
+
+    def relabeled_clone(self, relabels):
+        return self.__class__(
+            relabels.get(self.alias, self.alias), self.targets, self.sources, self.field
+        )
+
+    def get_lookup(self, lookup):
+        return self.output_field.get_lookup(lookup)
+
+    def resolve_expression(self, *args, **kwargs):
+        return self
+
+
+def get_normalized_value(value, lhs):
+    from django.db.models import Model
+
+    if isinstance(value, Model):
+        if value.pk is None:
+            # When the deprecation ends, replace with:
+            # raise ValueError(
+            #     "Model instances passed to related filters must be saved."
+            # )
+            warnings.warn(
+                "Passing unsaved model instances to related filters is deprecated.",
+                RemovedInDjango50Warning,
+            )
+        value_list = []
+        sources = lhs.output_field.path_infos[-1].target_fields
+        for source in sources:
+            while not isinstance(value, source.model) and source.remote_field:
+                source = source.remote_field.model._meta.get_field(
+                    source.remote_field.field_name
+                )
+            try:
+                value_list.append(getattr(value, source.attname))
+            except AttributeError:
+                # A case like Restaurant.objects.filter(place=restaurant_instance),
+                # where place is a OneToOneField and the primary key of Restaurant.
+                return (value.pk,)
+        return tuple(value_list)
+    if not isinstance(value, tuple):
+        return (value,)
+    return value
+
+
+class RelatedIn(In):
+    def get_prep_lookup(self):
+        if not isinstance(self.lhs, MultiColSource):
+            if self.rhs_is_direct_value():
+                # If we get here, we are dealing with single-column relations.
+                self.rhs = [get_normalized_value(val, self.lhs)[0] for val in self.rhs]
+                # We need to run the related field's get_prep_value(). Consider
+                # case ForeignKey to IntegerField given value 'abc'. The
+                # ForeignKey itself doesn't have validation for non-integers,
+                # so we must run validation using the target field.
+                if hasattr(self.lhs.output_field, "path_infos"):
+                    # Run the target field's get_prep_value. We can safely
+                    # assume there is only one as we don't get to the direct
+                    # value branch otherwise.
+                    target_field = self.lhs.output_field.path_infos[-1].target_fields[
+                        -1
+                    ]
+                    self.rhs = [target_field.get_prep_value(v) for v in self.rhs]
+            elif not getattr(self.rhs, "has_select_fields", True) and not getattr(
+                self.lhs.field.target_field, "primary_key", False
+            ):
+                self.rhs.clear_select_clause()
+                if (
+                    getattr(self.lhs.output_field, "primary_key", False)
+                    and self.lhs.output_field.model == self.rhs.model
+                ):
+                    # A case like
+                    # Restaurant.objects.filter(place__in=restaurant_qs), where
+                    # place is a OneToOneField and the primary key of
+                    # Restaurant.
+                    target_field = self.lhs.field.name
+                else:
+                    target_field = self.lhs.field.target_field.name
+                self.rhs.add_fields([target_field], True)
+        return super().get_prep_lookup()
+
+    def as_sql(self, compiler, connection):
+        if isinstance(self.lhs, MultiColSource):
+            # For multicolumn lookups we need to build a multicolumn where clause.
+            # This clause is either a SubqueryConstraint (for values that need
+            # to be compiled to SQL) or an OR-combined list of
+            # (col1 = val1 AND col2 = val2 AND ...) clauses.
+            from django.db.models.sql.where import (
+                AND,
+                OR,
+                SubqueryConstraint,
+                WhereNode,
+            )
+
+            root_constraint = WhereNode(connector=OR)
+            if self.rhs_is_direct_value():
+                values = [get_normalized_value(value, self.lhs) for value in self.rhs]
+                for value in values:
+                    value_constraint = WhereNode()
+                    for source, target, val in zip(
+                        self.lhs.sources, self.lhs.targets, value
+                    ):
+                        lookup_class = target.get_lookup("exact")
+                        lookup = lookup_class(
+                            target.get_col(self.lhs.alias, source), val
+                        )
+                        value_constraint.add(lookup, AND)
+                    root_constraint.add(value_constraint, OR)
+            else:
+                root_constraint.add(
+                    SubqueryConstraint(
+                        self.lhs.alias,
+                        [target.column for target in self.lhs.targets],
+                        [source.name for source in self.lhs.sources],
+                        self.rhs,
+                    ),
+                    AND,
+                )
+            return root_constraint.as_sql(compiler, connection)
+        return super().as_sql(compiler, connection)
+
+
+class RelatedLookupMixin:
+    def get_prep_lookup(self):
+        if not isinstance(self.lhs, MultiColSource) and not hasattr(
+            self.rhs, "resolve_expression"
+        ):
+            # If we get here, we are dealing with single-column relations.
+            self.rhs = get_normalized_value(self.rhs, self.lhs)[0]
+            # We need to run the related field's get_prep_value(). Consider case
+            # ForeignKey to IntegerField given value 'abc'. The ForeignKey itself
+            # doesn't have validation for non-integers, so we must run validation
+            # using the target field.
+            if self.prepare_rhs and hasattr(self.lhs.output_field, "path_infos"):
+                # Get the target field. We can safely assume there is only one
+                # as we don't get to the direct value branch otherwise.
+                target_field = self.lhs.output_field.path_infos[-1].target_fields[-1]
+                self.rhs = target_field.get_prep_value(self.rhs)
+
+        return super().get_prep_lookup()
+
+    def as_sql(self, compiler, connection):
+        if isinstance(self.lhs, MultiColSource):
+            assert self.rhs_is_direct_value()
+            self.rhs = get_normalized_value(self.rhs, self.lhs)
+            from django.db.models.sql.where import AND, WhereNode
+
+            root_constraint = WhereNode()
+            for target, source, val in zip(
+                self.lhs.targets, self.lhs.sources, self.rhs
+            ):
+                lookup_class = target.get_lookup(self.lookup_name)
+                root_constraint.add(
+                    lookup_class(target.get_col(self.lhs.alias, source), val), AND
+                )
+            return root_constraint.as_sql(compiler, connection)
+        return super().as_sql(compiler, connection)
+
+
+class RelatedExact(RelatedLookupMixin, Exact):
+    pass
+
+
+class RelatedLessThan(RelatedLookupMixin, LessThan):
+    pass
+
+
+class RelatedGreaterThan(RelatedLookupMixin, GreaterThan):
+    pass
+
+
+class RelatedGreaterThanOrEqual(RelatedLookupMixin, GreaterThanOrEqual):
+    pass
+
+
+class RelatedLessThanOrEqual(RelatedLookupMixin, LessThanOrEqual):
+    pass
+
+
+class RelatedIsNull(RelatedLookupMixin, IsNull):
+    pass

env/lib/python3.8/site-packages/django/db/models/fields/reverse_related.py

@@ -0,0 +1,396 @@
+"""
+"Rel objects" for related fields.
+
+"Rel objects" (for lack of a better name) carry information about the relation
+modeled by a related field and provide some utility functions. They're stored
+in the ``remote_field`` attribute of the field.
+
+They also act as reverse fields for the purposes of the Meta API because
+they're the closest concept currently available.
+"""
+
+from django.core import exceptions
+from django.utils.functional import cached_property
+from django.utils.hashable import make_hashable
+
+from . import BLANK_CHOICE_DASH
+from .mixins import FieldCacheMixin
+
+
+class ForeignObjectRel(FieldCacheMixin):
+    """
+    Used by ForeignObject to store information about the relation.
+
+    ``_meta.get_fields()`` returns this class to provide access to the field
+    flags for the reverse relation.
+    """
+
+    # Field flags
+    auto_created = True
+    concrete = False
+    editable = False
+    is_relation = True
+
+    # Reverse relations are always nullable (Django can't enforce that a
+    # foreign key on the related model points to this model).
+    null = True
+    empty_strings_allowed = False
+
+    def __init__(
+        self,
+        field,
+        to,
+        related_name=None,
+        related_query_name=None,
+        limit_choices_to=None,
+        parent_link=False,
+        on_delete=None,
+    ):
+        self.field = field
+        self.model = to
+        self.related_name = related_name
+        self.related_query_name = related_query_name
+        self.limit_choices_to = {} if limit_choices_to is None else limit_choices_to
+        self.parent_link = parent_link
+        self.on_delete = on_delete
+
+        self.symmetrical = False
+        self.multiple = True
+
+    # Some of the following cached_properties can't be initialized in
+    # __init__ as the field doesn't have its model yet. Calling these methods
+    # before field.contribute_to_class() has been called will result in
+    # AttributeError
+    @cached_property
+    def hidden(self):
+        return self.is_hidden()
+
+    @cached_property
+    def name(self):
+        return self.field.related_query_name()
+
+    @property
+    def remote_field(self):
+        return self.field
+
+    @property
+    def target_field(self):
+        """
+        When filtering against this relation, return the field on the remote
+        model against which the filtering should happen.
+        """
+        target_fields = self.path_infos[-1].target_fields
+        if len(target_fields) > 1:
+            raise exceptions.FieldError(
+                "Can't use target_field for multicolumn relations."
+            )
+        return target_fields[0]
+
+    @cached_property
+    def related_model(self):
+        if not self.field.model:
+            raise AttributeError(
+                "This property can't be accessed before self.field.contribute_to_class "
+                "has been called."
+            )
+        return self.field.model
+
+    @cached_property
+    def many_to_many(self):
+        return self.field.many_to_many
+
+    @cached_property
+    def many_to_one(self):
+        return self.field.one_to_many
+
+    @cached_property
+    def one_to_many(self):
+        return self.field.many_to_one
+
+    @cached_property
+    def one_to_one(self):
+        return self.field.one_to_one
+
+    def get_lookup(self, lookup_name):
+        return self.field.get_lookup(lookup_name)
+
+    def get_internal_type(self):
+        return self.field.get_internal_type()
+
+    @property
+    def db_type(self):
+        return self.field.db_type
+
+    def __repr__(self):
+        return "<%s: %s.%s>" % (
+            type(self).__name__,
+            self.related_model._meta.app_label,
+            self.related_model._meta.model_name,
+        )
+
+    @property
+    def identity(self):
+        return (
+            self.field,
+            self.model,
+            self.related_name,
+            self.related_query_name,
+            make_hashable(self.limit_choices_to),
+            self.parent_link,
+            self.on_delete,
+            self.symmetrical,
+            self.multiple,
+        )
+
+    def __eq__(self, other):
+        if not isinstance(other, self.__class__):
+            return NotImplemented
+        return self.identity == other.identity
+
+    def __hash__(self):
+        return hash(self.identity)
+
+    def __getstate__(self):
+        state = self.__dict__.copy()
+        # Delete the path_infos cached property because it can be recalculated
+        # at first invocation after deserialization. The attribute must be
+        # removed because subclasses like ManyToOneRel may have a PathInfo
+        # which contains an intermediate M2M table that's been dynamically
+        # created and doesn't exist in the .models module.
+        # This is a reverse relation, so there is no reverse_path_infos to
+        # delete.
+        state.pop("path_infos", None)
+        return state
+
+    def get_choices(
+        self,
+        include_blank=True,
+        blank_choice=BLANK_CHOICE_DASH,
+        limit_choices_to=None,
+        ordering=(),
+    ):
+        """
+        Return choices with a default blank choices included, for use
+        as <select> choices for this field.
+
+        Analog of django.db.models.fields.Field.get_choices(), provided
+        initially for utilization by RelatedFieldListFilter.
+        """
+        limit_choices_to = limit_choices_to or self.limit_choices_to
+        qs = self.related_model._default_manager.complex_filter(limit_choices_to)
+        if ordering:
+            qs = qs.order_by(*ordering)
+        return (blank_choice if include_blank else []) + [(x.pk, str(x)) for x in qs]
+
+    def is_hidden(self):
+        """Should the related object be hidden?"""
+        return bool(self.related_name) and self.related_name[-1] == "+"
+
+    def get_joining_columns(self):
+        return self.field.get_reverse_joining_columns()
+
+    def get_extra_restriction(self, alias, related_alias):
+        return self.field.get_extra_restriction(related_alias, alias)
+
+    def set_field_name(self):
+        """
+        Set the related field's name, this is not available until later stages
+        of app loading, so set_field_name is called from
+        set_attributes_from_rel()
+        """
+        # By default foreign object doesn't relate to any remote field (for
+        # example custom multicolumn joins currently have no remote field).
+        self.field_name = None
+
+    def get_accessor_name(self, model=None):
+        # This method encapsulates the logic that decides what name to give an
+        # accessor descriptor that retrieves related many-to-one or
+        # many-to-many objects. It uses the lowercased object_name + "_set",
+        # but this can be overridden with the "related_name" option. Due to
+        # backwards compatibility ModelForms need to be able to provide an
+        # alternate model. See BaseInlineFormSet.get_default_prefix().
+        opts = model._meta if model else self.related_model._meta
+        model = model or self.related_model
+        if self.multiple:
+            # If this is a symmetrical m2m relation on self, there is no
+            # reverse accessor.
+            if self.symmetrical and model == self.model:
+                return None
+        if self.related_name:
+            return self.related_name
+        return opts.model_name + ("_set" if self.multiple else "")
+
+    def get_path_info(self, filtered_relation=None):
+        if filtered_relation:
+            return self.field.get_reverse_path_info(filtered_relation)
+        else:
+            return self.field.reverse_path_infos
+
+    @cached_property
+    def path_infos(self):
+        return self.get_path_info()
+
+    def get_cache_name(self):
+        """
+        Return the name of the cache key to use for storing an instance of the
+        forward model on the reverse model.
+        """
+        return self.get_accessor_name()
+
+
+class ManyToOneRel(ForeignObjectRel):
+    """
+    Used by the ForeignKey field to store information about the relation.
+
+    ``_meta.get_fields()`` returns this class to provide access to the field
+    flags for the reverse relation.
+
+    Note: Because we somewhat abuse the Rel objects by using them as reverse
+    fields we get the funny situation where
+    ``ManyToOneRel.many_to_one == False`` and
+    ``ManyToOneRel.one_to_many == True``. This is unfortunate but the actual
+    ManyToOneRel class is a private API and there is work underway to turn
+    reverse relations into actual fields.
+    """
+
+    def __init__(
+        self,
+        field,
+        to,
+        field_name,
+        related_name=None,
+        related_query_name=None,
+        limit_choices_to=None,
+        parent_link=False,
+        on_delete=None,
+    ):
+        super().__init__(
+            field,
+            to,
+            related_name=related_name,
+            related_query_name=related_query_name,
+            limit_choices_to=limit_choices_to,
+            parent_link=parent_link,
+            on_delete=on_delete,
+        )
+
+        self.field_name = field_name
+
+    def __getstate__(self):
+        state = super().__getstate__()
+        state.pop("related_model", None)
+        return state
+
+    @property
+    def identity(self):
+        return super().identity + (self.field_name,)
+
+    def get_related_field(self):
+        """
+        Return the Field in the 'to' object to which this relationship is tied.
+        """
+        field = self.model._meta.get_field(self.field_name)
+        if not field.concrete:
+            raise exceptions.FieldDoesNotExist(
+                "No related field named '%s'" % self.field_name
+            )
+        return field
+
+    def set_field_name(self):
+        self.field_name = self.field_name or self.model._meta.pk.name
+
+
+class OneToOneRel(ManyToOneRel):
+    """
+    Used by OneToOneField to store information about the relation.
+
+    ``_meta.get_fields()`` returns this class to provide access to the field
+    flags for the reverse relation.
+    """
+
+    def __init__(
+        self,
+        field,
+        to,
+        field_name,
+        related_name=None,
+        related_query_name=None,
+        limit_choices_to=None,
+        parent_link=False,
+        on_delete=None,
+    ):
+        super().__init__(
+            field,
+            to,
+            field_name,
+            related_name=related_name,
+            related_query_name=related_query_name,
+            limit_choices_to=limit_choices_to,
+            parent_link=parent_link,
+            on_delete=on_delete,
+        )
+
+        self.multiple = False
+
+
+class ManyToManyRel(ForeignObjectRel):
+    """
+    Used by ManyToManyField to store information about the relation.
+
+    ``_meta.get_fields()`` returns this class to provide access to the field
+    flags for the reverse relation.
+    """
+
+    def __init__(
+        self,
+        field,
+        to,
+        related_name=None,
+        related_query_name=None,
+        limit_choices_to=None,
+        symmetrical=True,
+        through=None,
+        through_fields=None,
+        db_constraint=True,
+    ):
+        super().__init__(
+            field,
+            to,
+            related_name=related_name,
+            related_query_name=related_query_name,
+            limit_choices_to=limit_choices_to,
+        )
+
+        if through and not db_constraint:
+            raise ValueError("Can't supply a through model and db_constraint=False")
+        self.through = through
+
+        if through_fields and not through:
+            raise ValueError("Cannot specify through_fields without a through model")
+        self.through_fields = through_fields
+
+        self.symmetrical = symmetrical
+        self.db_constraint = db_constraint
+
+    @property
+    def identity(self):
+        return super().identity + (
+            self.through,
+            make_hashable(self.through_fields),
+            self.db_constraint,
+        )
+
+    def get_related_field(self):
+        """
+        Return the field in the 'to' object to which this relationship is tied.
+        Provided for symmetry with ManyToOneRel.
+        """
+        opts = self.through._meta
+        if self.through_fields:
+            field = opts.get_field(self.through_fields[0])
+        else:
+            for field in opts.fields:
+                rel = getattr(field, "remote_field", None)
+                if rel and rel.model == self.model:
+                    break
+        return field.foreign_related_fields[0]