Merge pull request #286 from naturalethic/allow-custom-model-config

Allow custom model config

docs/models/index.md

@@ -373,6 +373,31 @@ You can set this parameter by providing `Meta` class `constraints` argument.
         To set one column as unique use [`unique`](../fields/common-parameters.md#unique) common parameter. 
         Of course you can set many columns as unique with this param but each of them will be checked separately.
 
+### Pydantic configuration
+
+As each `ormar.Model` is also a `pydantic` model, you might want to tweak the settings of the pydantic configuration.
+
+The way to do this in pydantic is to adjust the settings on the `Config` class provided to your model, and it works exactly the same for ormer.Models.
+
+So in order to set your own preferences you need to provide not only the `Meta` class but also the `Config` class to your model.
+
+!!!note
+        To read more about available settings visit the [pydantic](https://pydantic-docs.helpmanual.io/usage/model_config/) config page.
+
+Note that if you do not provide your own configuration, ormar will do it for you.
+The default config provided is as follows:
+
+```python
+class Config(pydantic.BaseConfig):
+    orm_mode = True
+    validate_assignment = True
+```
+
+So to overwrite setting or provide your own a sample model can look like following:
+```Python hl_lines="15-16"
+--8<-- "../docs_src/models/docs016.py"
+```
+
 ## Model sort order
 
 When querying the database with given model by default the Model is ordered by the `primary_key`

docs_src/models/docs016.py

@@ -0,0 +1,20 @@
+import databases
+import sqlalchemy
+
+import ormar
+
+database = databases.Database("sqlite:///db.sqlite")
+metadata = sqlalchemy.MetaData()
+
+
+class Course(ormar.Model):
+    class Meta:
+        database = database
+        metadata = metadata
+
+    class Config:
+        allow_mutation = False
+
+    id: int = ormar.Integer(primary_key=True)
+    name: str = ormar.String(max_length=100)
+    completed: bool = ormar.Boolean(default=False)

ormar/models/metaclass.py

@@ -1,3 +1,4 @@
+import inspect
 from typing import (
     Any,
     Dict,
@@ -552,7 +553,21 @@ class ModelMetaclass(pydantic.main.ModelMetaclass):
         :param attrs: class namespace
         :type attrs: Dict
         """
-        attrs["Config"] = get_pydantic_base_orm_config()
+        DefaultConfig = get_pydantic_base_orm_config()
+        if "Config" in attrs:
+            ProvidedConfig = attrs["Config"]
+            if not inspect.isclass(ProvidedConfig):
+                raise ModelDefinitionError(
+                    f"Config provided for class {name} has to be a class."
+                )
+
+            class Config(ProvidedConfig, DefaultConfig):  # type: ignore
+                pass
+
+            attrs["Config"] = Config
+        else:
+            attrs["Config"] = DefaultConfig
+
         attrs["__name__"] = name
         attrs, model_fields = extract_annotations_and_default_vals(attrs)
         for base in reversed(bases):
@@ -580,9 +595,11 @@ class ModelMetaclass(pydantic.main.ModelMetaclass):
                 populate_meta_sqlalchemy_table_if_required(new_model.Meta)
                 expand_reverse_relationships(new_model)
                 # TODO: iterate only related fields
-                for name, field in new_model.Meta.model_fields.items():
+                for field_name, field in new_model.Meta.model_fields.items():
                     register_relation_in_alias_manager(field=field)
-                    add_field_descriptor(name=name, field=field, new_model=new_model)
+                    add_field_descriptor(
+                        name=field_name, field=field, new_model=new_model
+                    )
 
                 if (
                     new_model.Meta.pkname
@@ -640,10 +657,7 @@ class ModelMetaclass(pydantic.main.ModelMetaclass):
                     model=field.to,
                     access_chain=item,
                 )
-            else:
-                return FieldAccessor(
-                    source_model=cast(Type["Model"], self),
-                    field=field,
-                    access_chain=item,
-                )
+            return FieldAccessor(
+                source_model=cast(Type["Model"], self), field=field, access_chain=item,
+            )
         return object.__getattribute__(self, item)

tests/test_inheritance_and_pydantic_generation/test_inheritance_concrete.py

@@ -150,6 +150,12 @@ class Bus2(Car2):
     max_persons: int = ormar.Integer()
 
 
+class ImmutablePerson(Person):
+    class Config:
+        allow_mutation = False
+        validate_assignment = False
+
+
 @pytest.fixture(autouse=True, scope="module")
 def create_test_database():
     metadata.create_all(engine)
@@ -173,6 +179,13 @@ def test_duplicated_related_name_on_different_model():
             max_persons: int = ormar.Integer()
 
 
+def test_config_is_not_a_class_raises_error():
+    with pytest.raises(ModelDefinitionError):
+
+        class ImmutablePerson2(Person):
+            Config = dict(allow_mutation=False, validate_assignment=False)
+
+
 def test_field_redefining_in_concrete_models():
     class RedefinedField(DateFieldsModel):
         class Meta(ormar.ModelMeta):
@@ -495,3 +508,13 @@ async def test_inheritance_with_multi_relation():
             assert len(unicorns) == 2
             assert unicorns[1].name == "Unicorn 2"
             assert len(unicorns[1].co_owners) == 1
+
+
+def test_custom_config():
+    # Custom config inherits defaults
+    assert getattr(ImmutablePerson.__config__, "orm_mode") is True
+    # Custom config can override defaults
+    assert getattr(ImmutablePerson.__config__, "validate_assignment") is False
+    sam = ImmutablePerson(name="Sam")
+    with pytest.raises(TypeError):
+        sam.name = "Not Sam"