Fixed #29522 -- Refactored the Deserializer functions to classes.

Co-authored-by: Emad Mokhtar <emad.mokhtar@veneficus.nl>

1 files changed, 71 insertions, 48 deletions

diff --git a/django/core/serializers/python.py b/django/core/serializers/python.py
index 7ec894aa00..46ef9f0771 100644
--- a/django/core/serializers/python.py
+++ b/django/core/serializers/python.py
@@ -96,45 +96,60 @@ class Serializer(base.Serializer):
         return self.objects
 
 
-def Deserializer(
-    object_list, *, using=DEFAULT_DB_ALIAS, ignorenonexistent=False, **options
-):
+class Deserializer(base.Deserializer):
     """
     Deserialize simple Python objects back into Django ORM instances.
 
     It's expected that you pass the Python objects themselves (instead of a
     stream or a string) to the constructor
     """
-    handle_forward_references = options.pop("handle_forward_references", False)
-    field_names_cache = {}  # Model: <list of field_names>
 
-    for d in object_list:
+    def __init__(
+        self, object_list, *, using=DEFAULT_DB_ALIAS, ignorenonexistent=False, **options
+    ):
+        super().__init__(object_list, **options)
+        self.handle_forward_references = options.pop("handle_forward_references", False)
+        self.using = using
+        self.ignorenonexistent = ignorenonexistent
+        self.field_names_cache = {}  # Model: <list of field_names>
+        self._iterator = None
+
+    def __iter__(self):
+        for obj in self.stream:
+            yield from self._handle_object(obj)
+
+    def __next__(self):
+        if self._iterator is None:
+            self._iterator = iter(self)
+        return next(self._iterator)
+
+    def _handle_object(self, obj):
+        data = {}
+        m2m_data = {}
+        deferred_fields = {}
+
         # Look up the model and starting build a dict of data for it.
         try:
-            Model = _get_model(d["model"])
+            Model = self._get_model_from_node(obj["model"])
         except base.DeserializationError:
-            if ignorenonexistent:
-                continue
-            else:
-                raise
-        data = {}
-        if "pk" in d:
+            if self.ignorenonexistent:
+                return
+            raise
+        if "pk" in obj:
             try:
-                data[Model._meta.pk.attname] = Model._meta.pk.to_python(d.get("pk"))
+                data[Model._meta.pk.attname] = Model._meta.pk.to_python(obj.get("pk"))
             except Exception as e:
                 raise base.DeserializationError.WithData(
-                    e, d["model"], d.get("pk"), None
+                    e, obj["model"], obj.get("pk"), None
                 )
-        m2m_data = {}
-        deferred_fields = {}
 
-        if Model not in field_names_cache:
-            field_names_cache[Model] = {f.name for f in Model._meta.get_fields()}
-        field_names = field_names_cache[Model]
+        if Model not in self.field_names_cache:
+            self.field_names_cache[Model] = {f.name for f in Model._meta.get_fields()}
+        field_names = self.field_names_cache[Model]
 
         # Handle each field
-        for field_name, field_value in d["fields"].items():
-            if ignorenonexistent and field_name not in field_names:
+        for field_name, field_value in obj["fields"].items():
+            if self.ignorenonexistent and field_name not in field_names:
                 # skip fields no longer on model
                 continue
 
@@ -145,51 +160,59 @@ def Deserializer(
                 field.remote_field, models.ManyToManyRel
             ):
                 try:
-                    values = base.deserialize_m2m_values(
-                        field, field_value, using, handle_forward_references
-                    )
+                    values = self._handle_m2m_field_node(field, field_value)
+                    if values == base.DEFER_FIELD:
+                        deferred_fields[field] = field_value
+                    else:
+                        m2m_data[field.name] = values
                 except base.M2MDeserializationError as e:
                     raise base.DeserializationError.WithData(
-                        e.original_exc, d["model"], d.get("pk"), e.pk
+                        e.original_exc, obj["model"], obj.get("pk"), e.pk
                     )
-                if values == base.DEFER_FIELD:
-                    deferred_fields[field] = field_value
-                else:
-                    m2m_data[field.name] = values
+
             # Handle FK fields
             elif field.remote_field and isinstance(
                 field.remote_field, models.ManyToOneRel
             ):
                 try:
-                    value = base.deserialize_fk_value(
-                        field, field_value, using, handle_forward_references
-                    )
+                    value = self._handle_fk_field_node(field, field_value)
+                    if value == base.DEFER_FIELD:
+                        deferred_fields[field] = field_value
+                    else:
+                        data[field.attname] = value
                 except Exception as e:
                     raise base.DeserializationError.WithData(
-                        e, d["model"], d.get("pk"), field_value
+                        e, obj["model"], obj.get("pk"), field_value
                     )
-                if value == base.DEFER_FIELD:
-                    deferred_fields[field] = field_value
-                else:
-                    data[field.attname] = value
+
             # Handle all other fields
             else:
                 try:
                     data[field.name] = field.to_python(field_value)
                 except Exception as e:
                     raise base.DeserializationError.WithData(
-                        e, d["model"], d.get("pk"), field_value
+                        e, obj["model"], obj.get("pk"), field_value
                     )
 
-        obj = base.build_instance(Model, data, using)
-        yield base.DeserializedObject(obj, m2m_data, deferred_fields)
+        model_instance = base.build_instance(Model, data, self.using)
+        yield base.DeserializedObject(model_instance, m2m_data, deferred_fields)
 
+    def _handle_m2m_field_node(self, field, field_value):
+        return base.deserialize_m2m_values(
+            field, field_value, self.using, self.handle_forward_references
+        )
 
-def _get_model(model_identifier):
-    """Look up a model from an "app_label.model_name" string."""
-    try:
-        return apps.get_model(model_identifier)
-    except (LookupError, TypeError):
-        raise base.DeserializationError(
-            "Invalid model identifier: '%s'" % model_identifier
+    def _handle_fk_field_node(self, field, field_value):
+        return base.deserialize_fk_value(
+            field, field_value, self.using, self.handle_forward_references
         )
+
+    @staticmethod
+    def _get_model_from_node(model_identifier):
+        """Look up a model from an "app_label.model_name" string."""
+        try:
+            return apps.get_model(model_identifier)
+        except (LookupError, TypeError):
+            raise base.DeserializationError(
+                f"Invalid model identifier: {model_identifier}"
+            )