fix private attributes initialization

docs/releases.md

@@ -18,6 +18,7 @@
 
 *  Fix weakref `ReferenceError` error [#118](https://github.com/collerek/ormar/issues/118)
 *  Fix error raised by Through fields when pydantic `Config.extra="forbid"` is set
+*  Fix bug with `pydantic.PrivateAttr` not being initialized at `__init__` [#149](https://github.com/collerek/ormar/issues/149)
 
 ## 💬 Other
 *  Introduce link to `sqlalchemy-to-ormar` auto-translator for models

ormar/models/newbasemodel.py

@@ -189,6 +189,10 @@ class NewBaseModel(pydantic.BaseModel, ModelTableProxy, metaclass=ModelMetaclass
                 new_kwargs.get(related), self, to_register=True,
             )
 
+        if hasattr(self, "_init_private_attributes"):
+            # introduced in pydantic 1.7
+            self._init_private_attributes()
+
     def __setattr__(self, name: str, value: Any) -> None:  # noqa CCR001
         """
         Overwrites setattr in object to allow for special behaviour of certain params.
@@ -292,6 +296,7 @@ class NewBaseModel(pydantic.BaseModel, ModelTableProxy, metaclass=ModelMetaclass
             value = object.__getattribute__(self, "__dict__").get(item, None)
             value = object.__getattribute__(self, "_convert_json")(item, value, "loads")
             return value
+
         return object.__getattribute__(self, item)  # pragma: no cover
 
     def _verify_model_can_be_initialized(self) -> None:
@@ -590,6 +595,7 @@ class NewBaseModel(pydantic.BaseModel, ModelTableProxy, metaclass=ModelMetaclass
         for field in fields:
             if not relation_map or field not in relation_map:
                 continue
+            try:
                 nested_model = getattr(self, field)
                 if isinstance(nested_model, MutableSequence):
                     dict_instance[field] = self._extract_nested_models_from_list(
@@ -601,7 +607,7 @@ class NewBaseModel(pydantic.BaseModel, ModelTableProxy, metaclass=ModelMetaclass
                         exclude=self._skip_ellipsis(exclude, field),
                     )
                 elif nested_model is not None:
-                try:
+
                     dict_instance[field] = nested_model.dict(
                         relation_map=self._skip_ellipsis(
                             relation_map, field, default_return=dict()
@@ -609,10 +615,10 @@ class NewBaseModel(pydantic.BaseModel, ModelTableProxy, metaclass=ModelMetaclass
                         include=self._skip_ellipsis(include, field),
                         exclude=self._skip_ellipsis(exclude, field),
                     )
-                except ReferenceError:
-                    dict_instance[field] = None
                 else:
                     dict_instance[field] = None
+            except ReferenceError:
+                dict_instance[field] = None
         return dict_instance
 
     def dict(  # type: ignore # noqa A003

ormar/relations/querysetproxy.py

@@ -22,7 +22,7 @@ if TYPE_CHECKING:  # pragma no cover
     from ormar.relations import Relation
     from ormar.models import Model, T
     from ormar.queryset import QuerySet
-    from ormar import RelationType, ForeignKeyField
+    from ormar import RelationType
 else:
     T = TypeVar("T", bound="Model")
 

tests/test_model_definition/test_pydantic_private_attributes.py

@@ -0,0 +1,34 @@
+from typing import List
+
+import databases
+import sqlalchemy
+from pydantic import PrivateAttr
+
+import ormar
+from tests.settings import DATABASE_URL
+
+database = databases.Database(DATABASE_URL, force_rollback=True)
+metadata = sqlalchemy.MetaData()
+
+
+class BaseMeta(ormar.ModelMeta):
+    metadata = metadata
+    database = database
+
+
+class Subscription(ormar.Model):
+    class Meta(BaseMeta):
+        tablename = "subscriptions"
+
+    id: int = ormar.Integer(primary_key=True)
+    stripe_subscription_id: str = ormar.String(nullable=False, max_length=256)
+
+    _add_payments: List[str] = PrivateAttr(default_factory=list)
+
+    def add_payment(self, payment: str):
+        self._add_payments.append(payment)
+
+
+def test_private_attribute():
+    sub = Subscription(stripe_subscription_id="2312312sad231")
+    sub.add_payment("test")