django-rest-framework/api-guide/fields.html
2012-10-17 13:50:08 +01:00

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<li class="main"><a href="#serializer-fields">Serializer fields</a></li>
<li class="main"><a href="#generic-fields">Generic Fields</a></li>
<li><a href="#field">Field</a></li>
<li><a href="#writablefield">WritableField</a></li>
<li><a href="#modelfield">ModelField</a></li>
<li class="main"><a href="#typed-fields">Typed Fields</a></li>
<li><a href="#booleanfield">BooleanField</a></li>
<li><a href="#charfield">CharField</a></li>
<li><a href="#emailfield">EmailField</a></li>
<li><a href="#datefield">DateField</a></li>
<li><a href="#datetimefield">DateTimeField</a></li>
<li><a href="#integerfield">IntegerField</a></li>
<li><a href="#floatfield">FloatField</a></li>
<li class="main"><a href="#relational-fields">Relational Fields</a></li>
<li><a href="#relatedfield">RelatedField</a></li>
<li><a href="#manyrelatedfield">ManyRelatedField</a></li>
<li><a href="#primarykeyrelatedfield">PrimaryKeyRelatedField</a></li>
<li><a href="#manyprimarykeyrelatedfield">ManyPrimaryKeyRelatedField</a></li>
<li><a href="#hyperlinkedrelatedfield">HyperlinkedRelatedField</a></li>
<li><a href="#manyhyperlinkedrelatedfield">ManyHyperlinkedRelatedField</a></li>
<li><a href="#hyperlinkedidentityfield">HyperLinkedIdentityField</a></li>
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<p><a class="github" href="https://github.com/tomchristie/django-rest-framework/blob/restframework2/rest_framework/fields.py"><span class="label label-info">fields.py</span></a></p>
<h1 id="serializer-fields">Serializer fields</h1>
<blockquote>
<p>Flat is better than nested.</p>
<p>&mdash; <a href="http://www.python.org/dev/peps/pep-0020/">The Zen of Python</a></p>
</blockquote>
<p>Serializer fields handle converting between primative values and internal datatypes. They also deal with validating input values, as well as retrieving and setting the values from their parent objects.</p>
<hr />
<p><strong>Note:</strong> The serializer fields are declared in fields.py, but by convention you should import them using <code>from rest_framework import serializers</code> and refer to fields as <code>serializers.&lt;FieldName&gt;</code>.</p>
<hr />
<h1 id="generic-fields">Generic Fields</h1>
<p>These generic fields are used for representing arbitrary model fields or the output of model methods.</p>
<h2 id="field">Field</h2>
<p>A generic, <strong>read-only</strong> field. You can use this field for any attribute that does not need to support write operations.</p>
<p>For example, using the following model.</p>
<pre class="prettyprint lang-py"><code>class Account(models.Model):
owner = models.ForeignKey('auth.user')
name = models.CharField(max_length=100)
created = models.DateTimeField(auto_now_add=True)
payment_expiry = models.DateTimeField()
def has_expired(self):
now = datetime.datetime.now()
return now &gt; self.payment_expiry
</code></pre>
<p>A serializer definition that looked like this:</p>
<pre class="prettyprint lang-py"><code>class AccountSerializer(serializers.HyperlinkedModelSerializer):
expired = Field(source='has_expired')
class Meta:
fields = ('url', 'owner', 'name', 'expired')
</code></pre>
<p>Would produced output similar to:</p>
<pre class="prettyprint lang-py"><code>{
'url': 'http://example.com/api/accounts/3/',
'owner': 'http://example.com/api/users/12/',
'name': 'FooCorp business account',
'expired': True
}
</code></pre>
<p>Be default, the <code>Field</code> class will perform a basic translation of the source value into primative datatypes, falling back to unicode representations of complex datatypes when neccesary.</p>
<p>You can customize this behaviour by overriding the <code>.to_native(self, value)</code> method.</p>
<h2 id="writablefield">WritableField</h2>
<p>A field that supports both read and write operations. By itself <code>WriteableField</code> does not perform any translation of input values into a given type. You won't typically use this field directly, but you may want to override it and implement the <code>.to_native(self, value)</code> and <code>.from_native(self, value)</code> methods.</p>
<h2 id="modelfield">ModelField</h2>
<p>A generic field that can be tied to any arbitrary model field. The <code>ModelField</code> class delegates the task of serialization/deserialization to it's associated model field. This field can be used to create serializer fields for custom model fields, without having to create a new custom serializer field.</p>
<p><strong>Signature:</strong> <code>ModelField(model_field=&lt;Django ModelField class&gt;)</code></p>
<hr />
<h1 id="typed-fields">Typed Fields</h1>
<p>These fields represent basic datatypes, and support both reading and writing values.</p>
<h2 id="booleanfield">BooleanField</h2>
<p>A Boolean representation, corresponds to <code>django.db.models.fields.BooleanField</code>.</p>
<h2 id="charfield">CharField</h2>
<p>A text representation, optionally validates the text to be shorter than <code>max_length</code> and longer than <code>min_length</code>, corresponds to <code>django.db.models.fields.CharField</code>
or <code>django.db.models.fields.TextField</code>.</p>
<p><strong>Signature:</strong> <code>CharField([max_length=&lt;Integer&gt;[, min_length=&lt;Integer&gt;]])</code></p>
<h2 id="emailfield">EmailField</h2>
<p>A text representation, validates the text to be a valid e-mail adress. Corresponds to <code>django.db.models.fields.EmailField</code></p>
<h2 id="datefield">DateField</h2>
<p>A date representation. Corresponds to <code>django.db.models.fields.DateField</code></p>
<h2 id="datetimefield">DateTimeField</h2>
<p>A date and time representation. Corresponds to <code>django.db.models.fields.DateTimeField</code></p>
<h2 id="integerfield">IntegerField</h2>
<p>An integer representation. Corresponds to <code>django.db.models.fields.IntegerField</code>, <code>django.db.models.fields.SmallIntegerField</code>, <code>django.db.models.fields.PositiveIntegerField</code> and <code>django.db.models.fields.PositiveSmallIntegerField</code></p>
<h2 id="floatfield">FloatField</h2>
<p>A floating point representation. Corresponds to <code>django.db.models.fields.FloatField</code>.</p>
<hr />
<h1 id="relational-fields">Relational Fields</h1>
<p>Relational fields are used to represent model relationships. They can be applied to <code>ForeignKey</code>, <code>ManyToManyField</code> and <code>OneToOneField</code> relationships, as well as to reverse relationships, and custom relationships such as <code>GenericForeignKey</code>.</p>
<h2 id="relatedfield">RelatedField</h2>
<p>This field can be applied to any of the following:</p>
<ul>
<li>A <code>ForeignKey</code> field.</li>
<li>A <code>OneToOneField</code> field.</li>
<li>A reverse OneToOne relationship</li>
<li>Any other "to-one" relationship.</li>
</ul>
<p>By default <code>RelatedField</code> will represent the target of the field using it's <code>__unicode__</code> method.</p>
<p>You can customise this behaviour by subclassing <code>ManyRelatedField</code>, and overriding the <code>.to_native(self, value)</code> method.</p>
<h2 id="manyrelatedfield">ManyRelatedField</h2>
<p>This field can be applied to any of the following:</p>
<ul>
<li>A <code>ManyToManyField</code> field.</li>
<li>A reverse ManyToMany relationship.</li>
<li>A reverse ForeignKey relationship</li>
<li>Any other "to-many" relationship.</li>
</ul>
<p>By default <code>ManyRelatedField</code> will represent the targets of the field using their <code>__unicode__</code> method.</p>
<p>For example, given the following models:</p>
<pre class="prettyprint lang-py"><code>class TaggedItem(models.Model):
"""
Tags arbitrary model instances using a generic relation.
See: https://docs.djangoproject.com/en/dev/ref/contrib/contenttypes/
"""
tag = models.SlugField()
content_type = models.ForeignKey(ContentType)
object_id = models.PositiveIntegerField()
content_object = GenericForeignKey('content_type', 'object_id')
def __unicode__(self):
return self.tag
class Bookmark(models.Model):
"""
A bookmark consists of a URL, and 0 or more descriptive tags.
"""
url = models.URLField()
tags = GenericRelation(TaggedItem)
</code></pre>
<p>And a model serializer defined like this:</p>
<pre class="prettyprint lang-py"><code>class BookmarkSerializer(serializers.ModelSerializer):
tags = serializers.ManyRelatedField(source='tags')
class Meta:
model = Bookmark
exclude = ('id',)
</code></pre>
<p>The an example output format for a Bookmark instance would be:</p>
<pre class="prettyprint lang-py"><code>{
'tags': [u'django', u'python'],
'url': u'https://www.djangoproject.com/'
}
</code></pre>
<h2 id="primarykeyrelatedfield">PrimaryKeyRelatedField</h2>
<p>As with <code>RelatedField</code> field can be applied to any "to-one" relationship, such as a <code>ForeignKey</code> field.</p>
<p><code>PrimaryKeyRelatedField</code> will represent the target of the field using it's primary key.</p>
<p>Be default, <code>PrimaryKeyRelatedField</code> is read-write, although you can change this behaviour using the <code>readonly</code> flag.</p>
<h2 id="manyprimarykeyrelatedfield">ManyPrimaryKeyRelatedField</h2>
<p>As with <code>RelatedField</code> field can be applied to any "to-many" relationship, such as a <code>ManyToManyField</code> field, or a reverse <code>ForeignKey</code> relationship.</p>
<p><code>PrimaryKeyRelatedField</code> will represent the target of the field using their primary key.</p>
<p>Be default, <code>ManyPrimaryKeyRelatedField</code> is read-write, although you can change this behaviour using the <code>readonly</code> flag.</p>
<h2 id="hyperlinkedrelatedfield">HyperlinkedRelatedField</h2>
<h2 id="manyhyperlinkedrelatedfield">ManyHyperlinkedRelatedField</h2>
<h2 id="hyperlinkedidentityfield">HyperLinkedIdentityField</h2>
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