Add support for auto_now and auto_now_add

docs/declaring_models.md

@@ -52,13 +52,23 @@ All fields are required unless one of the following is set:
 * `allow_blank` - A boolean. Determine if empty strings are allowed. Sets the default to `""`.
 * `default` - A value or a callable (function).
 
+Special keyword arguments for `DateTime` and `Date` fields:
+
+* `auto_now` - Automatically set the field to now every time the object is saved. Useful for “last-modified” timestamps.
+* `auto_now_add` - Automatically set the field to now when the object is first created. Useful for creation of timestamps.
+
+Default=`datetime.date.today()` for `DateField` and `datetime.datetime.now()` for `DateTimeField`.
+
+!!! note
+    Setting `auto_now` or `auto_now_add` to True will cause the field to be read_only.
+
 The following column types are supported.
 See `TypeSystem` for [type-specific validation keyword arguments][typesystem-fields].
 
 * `orm.BigInteger()`
 * `orm.Boolean()`
-* `orm.Date()`
-* `orm.DateTime()`
+* `orm.Date(auto_now, auto_now_add)`
+* `orm.DateTime(auto_now, auto_now_add)`
 * `orm.Decimal()`
 * `orm.Email(max_length)`
 * `orm.Enum()`

orm/fields.py

@@ -1,4 +1,5 @@
 import typing
+from datetime import date, datetime
 
 import sqlalchemy
 import typesystem
@@ -100,16 +101,31 @@ def get_column_type(self):
         return sqlalchemy.Boolean()
 
 
-class DateTime(ModelField):
+class AutoNowMixin(ModelField):
+    def __init__(self, auto_now=False, auto_now_add=False, **kwargs):
+        self.auto_now = auto_now
+        self.auto_now_add = auto_now_add
+        if auto_now_add and auto_now:
+            raise ValueError("auto_now and auto_now_add cannot be both True")
+        if auto_now_add or auto_now:
+            kwargs["read_only"] = True
+        super().__init__(**kwargs)
+
+
+class DateTime(AutoNowMixin):
     def get_validator(self, **kwargs) -> typesystem.Field:
+        if self.auto_now_add or self.auto_now:
+            kwargs["default"] = datetime.now
         return typesystem.DateTime(**kwargs)
 
     def get_column_type(self):
         return sqlalchemy.DateTime()
 
 
-class Date(ModelField):
+class Date(AutoNowMixin):
     def get_validator(self, **kwargs) -> typesystem.Field:
+        if self.auto_now_add or self.auto_now:
+            kwargs["default"] = date.today
         return typesystem.Date(**kwargs)
 
     def get_column_type(self):

orm/models.py

@@ -6,7 +6,7 @@
 from sqlalchemy.ext.asyncio import create_async_engine
 
 from orm.exceptions import MultipleMatches, NoMatch
-from orm.fields import String, Text
+from orm.fields import Date, DateTime, String, Text
 
 FILTER_OPERATORS = {
     "exact": "__eq__",
@@ -21,6 +21,15 @@
 }
 
 
+def _update_auto_now_fields(values, fields):
+    for key, value in fields.items():
+        if isinstance(value, DateTime) and value.auto_now:
+            values[key] = value.validator.get_default_value()
+        elif isinstance(value, Date) and value.auto_now:
+            values[key] = value.validator.get_default_value()
+    return values
+
+
 class ModelRegistry:
     def __init__(self, database: databases.Database) -> None:
         self.database = database
@@ -400,7 +409,6 @@ async def create(self, **kwargs):
             fields={key: value.validator for key, value in fields.items()}
         )
         kwargs = validator.validate(kwargs)
-
         for key, value in fields.items():
             if value.validator.read_only and value.validator.has_default():
                 kwargs[key] = value.validator.get_default_value()
@@ -429,8 +437,9 @@ async def update(self, **kwargs) -> None:
             if key in kwargs
         }
         validator = typesystem.Schema(fields=fields)
-        kwargs = validator.validate(kwargs)
-
+        kwargs = _update_auto_now_fields(
+            validator.validate(kwargs), self.model_cls.fields
+        )
         expr = self.table.update().values(**kwargs)
 
         for filter_clause in self.filter_clauses:
@@ -513,11 +522,9 @@ async def update(self, **kwargs):
             key: field.validator for key, field in self.fields.items() if key in kwargs
         }
         validator = typesystem.Schema(fields=fields)
-        kwargs = validator.validate(kwargs)
-
+        kwargs = _update_auto_now_fields(validator.validate(kwargs), self.fields)
         pk_column = getattr(self.table.c, self.pkname)
         expr = self.table.update().values(**kwargs).where(pk_column == self.pk)
-
         await self.database.execute(expr)
 
         # Update the model instance.

tests/test_columns.py

@@ -33,6 +33,10 @@ class Product(orm.Model):
         "created": orm.DateTime(default=datetime.datetime.now),
         "created_day": orm.Date(default=datetime.date.today),
         "created_time": orm.Time(default=time),
+        "created_date": orm.Date(auto_now_add=True),
+        "created_datetime": orm.DateTime(auto_now_add=True),
+        "updated_datetime": orm.DateTime(auto_now=True),
+        "updated_date": orm.Date(auto_now=True),
         "data": orm.JSON(default={}),
         "description": orm.Text(allow_blank=True),
         "huge_number": orm.BigInteger(default=0),
@@ -69,10 +73,13 @@ async def rollback_transactions():
 
 async def test_model_crud():
     product = await Product.objects.create()
-
     product = await Product.objects.get(pk=product.pk)
     assert product.created.year == datetime.datetime.now().year
     assert product.created_day == datetime.date.today()
+    assert product.created_date == datetime.date.today()
+    assert product.created_datetime.date() == datetime.datetime.now().date()
+    assert product.updated_date == datetime.date.today()
+    assert product.updated_datetime.date() == datetime.datetime.now().date()
     assert product.data == {}
     assert product.description == ""
     assert product.huge_number == 0
@@ -96,6 +103,8 @@ async def test_model_crud():
     assert product.price == decimal.Decimal("999.99")
     assert product.uuid == uuid.UUID("01175cde-c18f-4a13-a492-21bd9e1cb01b")
 
+    last_updated_datetime = product.updated_datetime
+    last_updated_date = product.updated_date
     user = await User.objects.create()
     assert isinstance(user.pk, uuid.UUID)
 
@@ -114,3 +123,22 @@ async def test_model_crud():
     user = await User.objects.get()
     assert isinstance(user.ipaddress, (ipaddress.IPv4Address, ipaddress.IPv6Address))
     assert user.url == "https://encode.io"
+    # Test auto_now update
+    await product.update(
+        data={"foo": 1234},
+    )
+    assert product.updated_datetime != last_updated_datetime
+    assert product.updated_date == last_updated_date
+
+
+async def test_both_auto_now_and_auto_now_add_raise_error():
+    with pytest.raises(ValueError):
+
+        class Product(orm.Model):
+            registry = models
+            fields = {
+                "id": orm.Integer(primary_key=True),
+                "created_datetime": orm.DateTime(auto_now_add=True, auto_now=True),
+            }
+
+        await Product.objects.create()