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Diffstat (limited to 'docs/api-guide')
| -rw-r--r-- | docs/api-guide/relations.md | 81 |
1 files changed, 41 insertions, 40 deletions
diff --git a/docs/api-guide/relations.md b/docs/api-guide/relations.md index ad981b2b..7d19eba2 100644 --- a/docs/api-guide/relations.md +++ b/docs/api-guide/relations.md @@ -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. |