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3.0 docs and tidy-up for serializer relationships

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Tom Christie 2014-11-26 11:30:49 +00:00
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docs/api-guide/relations.md
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@ -16,6 +16,20 @@ Relational fields are used to represent model relationships. They can be applie
---
#### Inspecting automatically generated relationships.
When using the `ModelSerializer` class, serializer fields and relationships will be automatically generated for you. Inspecting these automatically generated fields can be a useful tool for determining how to customize the relationship style.
To do so, open the Django shell, using `python manage.py shell`, then import the serializer class, instantiate it, and print the object representation…
>>> from myapp.serializers import AccountSerializer
>>> serializer = AccountSerializer()
>>> print repr(serializer) # Or `print(repr(serializer))` in Python 3.x.
AccountSerializer():
id = IntegerField(label='ID', read_only=True)
name = CharField(allow_blank=True, max_length=100, required=False)
owner = PrimaryKeyRelatedField(queryset=User.objects.all())
# API Reference
In order to explain the various types of relational fields, we'll use a couple of simple models for our examples. Our models will be for music albums, and the tracks listed on each album.
@ -37,14 +51,14 @@ In order to explain the various types of relational fields, we'll use a couple o
def __unicode__(self):
return '%d: %s' % (self.order, self.title)
## RelatedField
## StringRelatedField
`RelatedField` may be used to represent the target of the relationship using its `__unicode__` method.
`StringRelatedField` may be used to represent the target of the relationship using its `__unicode__` method.
For example, the following serializer.
class AlbumSerializer(serializers.ModelSerializer):
tracks = serializers.RelatedField(many=True)
tracks = serializers.StringRelatedField(many=True)
class Meta:
model = Album
@ -99,9 +113,9 @@ By default this field is read-write, although you can change this behavior using
**Arguments**:
* `queryset` - The queryset used for model instance lookups when validating the field input. Relationships must either set a queryset explicitly, or set `read_only=True`.
* `many` - If applied to a to-many relationship, you should set this argument to `True`.
* `required` - If set to `False`, the field will accept values of `None` or the empty-string for nullable relationships.
* `queryset` - By default `ModelSerializer` classes will use the default queryset for the relationship. `Serializer` classes must either set a queryset explicitly, or set `read_only=True`.
* `allow_null` - If set to `True`, the field will accept values of `None` or the empty string for nullable relationships. Defaults to `False`.
## HyperlinkedRelatedField
@ -110,8 +124,11 @@ By default this field is read-write, although you can change this behavior using
For example, the following serializer:
class AlbumSerializer(serializers.ModelSerializer):
tracks = serializers.HyperlinkedRelatedField(many=True, read_only=True,
view_name='track-detail')
tracks = serializers.HyperlinkedRelatedField(
many=True,
read_only=True,
view_name='track-detail'
)
class Meta:
model = Album
@ -134,11 +151,12 @@ By default this field is read-write, although you can change this behavior using
**Arguments**:
* `view_name` - The view name that should be used as the target of the relationship. If you're using [the standard router classes][routers] this wil be a string with the format `<modelname>-detail`. **required**.
* `view_name` - The view name that should be used as the target of the relationship. If you're using [the standard router classes][routers] this will be a string with the format `<modelname>-detail`. **required**.
* `queryset` - The queryset used for model instance lookups when validating the field input. Relationships must either set a queryset explicitly, or set `read_only=True`.
* `many` - If applied to a to-many relationship, you should set this argument to `True`.
* `required` - If set to `False`, the field will accept values of `None` or the empty-string for nullable relationships.
* `queryset` - By default `ModelSerializer` classes will use the default queryset for the relationship. `Serializer` classes must either set a queryset explicitly, or set `read_only=True`.
* `allow_null` - If set to `True`, the field will accept values of `None` or the empty string for nullable relationships. Defaults to `False`.
* `lookup_field` - The field on the target that should be used for the lookup. Should correspond to a URL keyword argument on the referenced view. Default is `'pk'`.
* `lookup_url_kwarg` - The name of the keyword argument defined in the URL conf that corresponds to the lookup field. Defaults to using the same value as `lookup_field`.
* `format` - If using format suffixes, hyperlinked fields will use the same format suffix for the target unless overridden by using the `format` argument.
## SlugRelatedField
@ -148,8 +166,11 @@ By default this field is read-write, although you can change this behavior using
For example, the following serializer:
class AlbumSerializer(serializers.ModelSerializer):
tracks = serializers.SlugRelatedField(many=True, read_only=True,
slug_field='title')
tracks = serializers.SlugRelatedField(
many=True,
read_only=True,
slug_field='title'
)
class Meta:
model = Album
@ -175,9 +196,9 @@ When using `SlugRelatedField` as a read-write field, you will normally want to e
**Arguments**:
* `slug_field` - The field on the target that should be used to represent it. This should be a field that uniquely identifies any given instance. For example, `username`. **required**
* `queryset` - The queryset used for model instance lookups when validating the field input. Relationships must either set a queryset explicitly, or set `read_only=True`.
* `many` - If applied to a to-many relationship, you should set this argument to `True`.
* `required` - If set to `False`, the field will accept values of `None` or the empty-string for nullable relationships.
* `queryset` - By default `ModelSerializer` classes will use the default queryset for the relationship. `Serializer` classes must either set a queryset explicitly, or set `read_only=True`.
* `allow_null` - If set to `True`, the field will accept values of `None` or the empty string for nullable relationships. Defaults to `False`.
## HyperlinkedIdentityField
@ -245,9 +266,9 @@ Would serialize to a nested representation like this:
# Custom relational fields
To implement a custom relational field, you should override `RelatedField`, and implement the `.to_native(self, value)` method. This method takes the target of the field as the `value` argument, and should return the representation that should be used to serialize the target.
To implement a custom relational field, you should override `RelatedField`, and implement the `.to_representation(self, value)` method. This method takes the target of the field as the `value` argument, and should return the representation that should be used to serialize the target. The `value` argument will typically be a model instance.
If you want to implement a read-write relational field, you must also implement the `.from_native(self, data)` method, and add `read_only = False` to the class definition.
If you want to implement a read-write relational field, you must also implement the `.to_internal_value(self, data)` method.
## Example
@ -256,7 +277,7 @@ For, example, we could define a relational field, to serialize a track to a cust
import time
class TrackListingField(serializers.RelatedField):
def to_native(self, value):
def to_representation(self, value):
duration = time.strftime('%M:%S', time.gmtime(value.duration))
return 'Track %d: %s (%s)' % (value.order, value.name, duration)
@ -350,7 +371,7 @@ We could define a custom field that could be used to serialize tagged instances,
A custom field to use for the `tagged_object` generic relationship.
"""
def to_native(self, value):
def to_representation(self, value):
"""
Serialize tagged objects to a simple textual representation.
"""
@ -360,9 +381,9 @@ We could define a custom field that could be used to serialize tagged instances,
return 'Note: ' + value.text
raise Exception('Unexpected type of tagged object')
If you need the target of the relationship to have a nested representation, you can use the required serializers inside the `.to_native()` method:
If you need the target of the relationship to have a nested representation, you can use the required serializers inside the `.to_native()` method:
def to_native(self, value):
def to_representation(self, value):
"""
Serialize bookmark instances using a bookmark serializer,
and note instances using a note serializer.
@ -404,7 +425,6 @@ attributes are not configured to correctly match the URL conf.
#### get_object(self, queryset, view_name, view_args, view_kwargs)
This method should the object that corresponds to the matched URL conf arguments.
May raise an `ObjectDoesNotExist` exception.
@ -425,25 +445,6 @@ For example, if all your object URLs used both a account and a slug in the the U
---
## Deprecated APIs
The following classes have been deprecated, in favor of the `many=<bool>` syntax.
They continue to function, but their usage will raise a `PendingDeprecationWarning`, which is silent by default.
* `ManyRelatedField`
* `ManyPrimaryKeyRelatedField`
* `ManyHyperlinkedRelatedField`
* `ManySlugRelatedField`
The `null=<bool>` flag has been deprecated in favor of the `required=<bool>` flag. It will continue to function, but will raise a `PendingDeprecationWarning`.
In the 2.3 release, these warnings will be escalated to a `DeprecationWarning`, which is loud by default.
In the 2.4 release, these parts of the API will be removed entirely.
For more details see the [2.2 release announcement][2.2-announcement].
---
# Third Party Packages
The following third party packages are also available.