fix server_default not setting value in defaults, pop server_default fields if set to None, add tests, update docs

docs/fields.md

@@ -68,13 +68,31 @@ Used both in sql and pydantic.
 
 A default value used if no other value is passed.
 
-In sql invoked on the server side so you can pass i.e. sql function (like now() wrapped in sqlalchemy text() clause).
+In sql invoked on the server side so you can pass i.e. sql function (like now() or query/value wrapped in sqlalchemy text() clause).
 
 If the field has a server_default value it becomes optional.
 
 You can pass a static value or a Callable (function etc.)
 
 Used in sql only.
+
+Sample usage:
+
+```Python hl_lines="19-21"
+--8<-- "../docs_src/fields/docs004.py"
+```
+
+!!!warning
+    `server_default` accepts `str`, `sqlalchemy.sql.elements.ClauseElement` or `sqlalchemy.sql.elements.TextClause`
+    so if you want to set i.e. Integer value you need to wrap it in `sqlalchemy.text()` function like above
+
+!!!tip
+    You can pass also valid sql (dialect specific) wrapped in `sqlalchemy.text()`
+    
+    For example `func.now()` above could be exchanged for `text('(CURRENT_TIMESTAMP)')` for sqlite backend
+
+!!!info
+    `server_default` is passed straight to sqlalchemy table definition so you can read more in [server default][server default] sqlalchemy documentation
  
 ### index
 
@@ -240,4 +258,5 @@ You can use either `length` and `precision` parameters or `max_digits` and `deci
 
 [relations]: ./relations.md
 [queries]: ./queries.md
-[pydantic]: https://pydantic-docs.helpmanual.io/usage/types/#constrained-types
+[pydantic]: https://pydantic-docs.helpmanual.io/usage/types/#constrained-types
+[server default]: https://docs.sqlalchemy.org/en/13/core/defaults.html#server-invoked-ddl-explicit-default-expressions

docs_src/fields/docs004.py

@@ -0,0 +1,21 @@
+import databases
+import sqlalchemy
+from sqlalchemy import func, text
+
+import ormar
+
+database = databases.Database("sqlite:///test.db")
+metadata = sqlalchemy.MetaData()
+
+
+class Product(ormar.Model):
+    class Meta:
+        tablename = "product"
+        metadata = metadata
+        database = database
+
+    id: ormar.Integer(primary_key=True)
+    name: ormar.String(max_length=100)
+    company: ormar.String(max_length=200, server_default='Acme')
+    sort_order: ormar.Integer(server_default=text("10"))
+    created: ormar.DateTime(server_default=func.now())

ormar/__init__.py

@@ -28,7 +28,7 @@ class UndefinedType:  # pragma no cover
 
 Undefined = UndefinedType()
 
-__version__ = "0.3.9"
+__version__ = "0.3.11"
 __all__ = [
     "Integer",
     "BigInteger",

ormar/fields/base.py

@@ -33,10 +33,10 @@ class BaseField:
     server_default: Any
 
     @classmethod
-    def default_value(cls) -> Optional[FieldInfo]:
+    def default_value(cls, use_server: bool = False) -> Optional[FieldInfo]:
         if cls.is_auto_primary_key():
             return Field(default=None)
-        if cls.has_default():
+        if cls.has_default(use_server=use_server):
             default = cls.default if cls.default is not None else cls.server_default
             if callable(default):
                 return Field(default_factory=default)
@@ -44,16 +44,22 @@ class BaseField:
         return None
 
     @classmethod
-    def get_default(cls) -> Any:
+    def get_default(cls, use_server: bool = False) -> Any: # noqa CCR001
         if cls.has_default():
-            default = cls.default if cls.default is not None else cls.server_default
+            default = (
+                cls.default
+                if cls.default is not None
+                else (cls.server_default if use_server else None)
+            )
             if callable(default):
                 default = default()
             return default
 
     @classmethod
-    def has_default(cls) -> bool:
-        return cls.default is not None or cls.server_default is not None
+    def has_default(cls, use_server: bool = True) -> bool:
+        return cls.default is not None or (
+            cls.server_default is not None and use_server
+        )
 
     @classmethod
     def is_auto_primary_key(cls) -> bool:

ormar/models/model.py

@@ -129,7 +129,7 @@ class Model(NewBaseModel):
 
         if not self.pk and self.Meta.model_fields[self.Meta.pkname].autoincrement:
             self_fields.pop(self.Meta.pkname, None)
-        self_fields = self.objects._populate_default_values(self_fields)
+        self_fields = self.populate_default_values(self_fields)
         expr = self.Meta.table.insert()
         expr = expr.values(**self_fields)
         item_id = await self.Meta.database.execute(expr)

ormar/models/modelproxy.py

@@ -49,6 +49,16 @@ class ModelTableProxy:
                     model_dict.pop(field, None)
         return model_dict
 
+    @classmethod
+    def populate_default_values(cls, new_kwargs: Dict) -> Dict:
+        for field_name, field in cls.Meta.model_fields.items():
+            if field_name not in new_kwargs and field.has_default(use_server=False):
+                new_kwargs[field_name] = field.get_default()
+            # clear fields with server_default set as None
+            if field.server_default is not None and not new_kwargs.get(field_name):
+                new_kwargs.pop(field_name, None)
+        return new_kwargs
+
     @classmethod
     def get_column_alias(cls, field_name: str) -> str:
         field = cls.Meta.model_fields.get(field_name)

ormar/queryset/queryset.py

@@ -73,16 +73,10 @@ class QuerySet:
     def _prepare_model_to_save(self, new_kwargs: dict) -> dict:
         new_kwargs = self._remove_pk_from_kwargs(new_kwargs)
         new_kwargs = self.model.substitute_models_with_pks(new_kwargs)
-        new_kwargs = self._populate_default_values(new_kwargs)
+        new_kwargs = self.model.populate_default_values(new_kwargs)
         new_kwargs = self.model.translate_columns_to_aliases(new_kwargs)
         return new_kwargs
 
-    def _populate_default_values(self, new_kwargs: dict) -> dict:
-        for field_name, field in self.model_meta.model_fields.items():
-            if field_name not in new_kwargs and field.has_default():
-                new_kwargs[field_name] = field.get_default()
-        return new_kwargs
-
     def _remove_pk_from_kwargs(self, new_kwargs: dict) -> dict:
         pkname = self.model_meta.pkname
         pk = self.model_meta.model_fields[pkname]
@@ -300,6 +294,9 @@ class QuerySet:
         if pk and isinstance(pk, self.model.pk_type()):
             setattr(instance, self.model_meta.pkname, pk)
 
+        # refresh server side defaults
+        instance = await instance.load()
+
         return instance
 
     async def bulk_create(self, objects: List["Model"]) -> None:

tests/test_server_default.py

@@ -0,0 +1,80 @@
+import asyncio
+import time
+from datetime import datetime
+
+import databases
+import pytest
+import sqlalchemy
+from sqlalchemy import func, text
+
+import ormar
+from tests.settings import DATABASE_URL
+
+database = databases.Database(DATABASE_URL, force_rollback=True)
+metadata = sqlalchemy.MetaData()
+
+
+class Product(ormar.Model):
+    class Meta:
+        tablename = "product"
+        metadata = metadata
+        database = database
+
+    id: ormar.Integer(primary_key=True)
+    name: ormar.String(max_length=100)
+    company: ormar.String(max_length=200, server_default='Acme')
+    sort_order: ormar.Integer(server_default=text("10"))
+    created: ormar.DateTime(server_default=func.now())
+
+
+@pytest.fixture(scope="module")
+def event_loop():
+    loop = asyncio.get_event_loop()
+    yield loop
+    loop.close()
+
+
+@pytest.fixture(autouse=True, scope="module")
+async def create_test_database():
+    engine = sqlalchemy.create_engine(DATABASE_URL)
+    metadata.drop_all(engine)
+    metadata.create_all(engine)
+    yield
+    metadata.drop_all(engine)
+
+
+def test_table_defined_properly():
+    assert Product.Meta.model_fields['created'].nullable
+    assert not Product.__fields__['created'].required
+    assert Product.Meta.table.columns['created'].server_default.arg.name == 'now'
+
+
+@pytest.mark.asyncio
+async def test_model_creation():
+    p1 = Product(name='Test')
+    assert p1.created is None
+    await p1.save()
+    await p1.load()
+    assert p1.created is not None
+    assert p1.company == 'Acme'
+    assert p1.sort_order == 10
+
+    date = datetime.strptime('2020-10-27 11:30', '%Y-%m-%d %H:%M')
+    p3 = await Product.objects.create(name='Test2', created=date, company='Roadrunner', sort_order=1)
+    assert p3.created is not None
+    assert p3.created == date
+    assert p1.created != p3.created
+    assert p3.company == 'Roadrunner'
+    assert p3.sort_order == 1
+
+    p3 = await Product.objects.get(name='Test2')
+    assert p3.company == 'Roadrunner'
+    assert p3.sort_order == 1
+
+    time.sleep(1)
+
+    p2 = await Product.objects.create(name='Test3')
+    assert p2.created is not None
+    assert p1.created != p2.created
+    assert p2.company == 'Acme'
+    assert p2.sort_order == 10