queryset-level update method (#112)

Author: aminalaee

docs/making_queries.md

@@ -138,7 +138,7 @@ It's not very common, but to delete all rows in a table:
 await Note.objects.delete()
 ```
 
-You can also call delete on a queried instance:
+You can also call `.delete()` on a queried instance:
 
 ```python
 note = await Note.objects.first()
@@ -182,16 +182,23 @@ note = await Note.objects.get(id=1)
 
 ### .update()
 
-`.update()` method is defined on model instances.
-You need to query to get a `Note` instance first:
+You can update instances by calling `.update()` on a queryset:
 
 ```python
-note = await Note.objects.first()
+await Note.objects.filter(completed=True).update(completed=False)
 ```
 
-Then update the field(s):
+It's not very common, but to update all rows in a table:
 
 ```python
+await Note.objects.update(completed=False)
+```
+
+You can also call `.update()` on a queried instance:
+
+```python
+note = await Note.objects.first()
+
 await note.update(completed=True)
 ```
 

orm/models.py

@@ -407,7 +407,23 @@ async def delete(self) -> None:
         for filter_clause in self.filter_clauses:
             expr = expr.where(filter_clause)
 
-        return await self.database.execute(expr)
+        await self.database.execute(expr)
+
+    async def update(self, **kwargs) -> None:
+        fields = {
+            key: field.validator
+            for key, field in self.model_cls.fields.items()
+            if key in kwargs
+        }
+        validator = typesystem.Schema(fields=fields)
+        kwargs = validator.validate(kwargs)
+
+        expr = self.table.update().values(**kwargs)
+
+        for filter_clause in self.filter_clauses:
+            expr = expr.where(filter_clause)
+
+        await self.database.execute(expr)
 
     async def get_or_create(self, **kwargs) -> typing.Tuple[typing.Any, bool]:
         try:
@@ -459,19 +475,15 @@ def table(self) -> sqlalchemy.Table:
         return self.__class__.table
 
     async def update(self, **kwargs):
-        # Validate the keyword arguments.
         fields = {
             key: field.validator for key, field in self.fields.items() if key in kwargs
         }
         validator = typesystem.Schema(fields=fields)
         kwargs = validator.validate(kwargs)
 
-        # Build the update expression.
         pk_column = getattr(self.table.c, self.pkname)
-        expr = self.table.update()
-        expr = expr.values(**kwargs).where(pk_column == self.pk)
+        expr = self.table.update().values(**kwargs).where(pk_column == self.pk)
 
-        # Perform the update.
         await self.database.execute(expr)
 
         # Update the model instance.

tests/test_foreignkey.py

@@ -178,3 +178,13 @@ async def test_queryset_delete_with_fk():
     await Track.objects.filter(album=malibu).delete()
     assert await Track.objects.filter(album=malibu).count() == 0
     assert await Track.objects.filter(album=wall).count() == 1
+
+
+async def test_queryset_update_with_fk():
+    malibu = await Album.objects.create(name="Malibu")
+    wall = await Album.objects.create(name="The Wall")
+    await Track.objects.create(album=malibu, title="The Bird", position=1)
+
+    await Track.objects.filter(album=malibu).update(album=wall)
+    assert await Track.objects.filter(album=malibu).count() == 0
+    assert await Track.objects.filter(album=wall).count() == 1

tests/test_models.py

@@ -273,3 +273,17 @@ async def test_queryset_delete():
 
     await Product.objects.delete()
     assert await Product.objects.count() == 0
+
+
+async def test_queryset_update():
+    shirt = await Product.objects.create(name="Shirt", rating=5)
+    tie = await Product.objects.create(name="Tie", rating=5)
+
+    await Product.objects.filter(pk=shirt.id).update(rating=3)
+    shirt = await Product.objects.get(pk=shirt.id)
+    assert shirt.rating == 3
+    assert await Product.objects.get(pk=tie.id) == tie
+
+    await Product.objects.update(rating=3)
+    tie = await Product.objects.get(pk=tie.id)
+    assert tie.rating == 3