Field Attributes

The Field Attributes feature allows you to dynamically modify serializer field attributes at runtime. This enables you to change field behavior without creating multiple serializer classes.

Basic Usage

To modify field attributes, pass a field_attributes dictionary when instantiating your serializer:

serializer = BlogPostSerializer(
    instance=post,
    field_attributes={
        'title': {'write_only': True},
        'content': {'read_only': False}
    }
)

Supported Attribute Types

Static Attributes

Direct value assignments:

{
    'title': {'required': True},
    'content': {'help_text': 'Main post content'}
}

Callable Attributes

Functions that receive (instance, context) and return the attribute value:

def make_write_only(instance, context):
    return not context['request'].user.is_staff

{
    'secret_field': {'write_only': make_write_only}
}

Common Attributes

Attribute	Description	Example Value
`write_only`	Field is write-only (excluded from output)	`True`/`False`
`read_only`	Field is read-only (excluded from input)	`True`/`False`
`required`	Whether field is mandatory	`True`/`False`
`help_text`	Descriptive text for the field	`"User's full name"`
`default`	Default value if field not provided	`"draft"`
`allow_null`	Whether `None` is valid value	`True`/`False`

Examples

API Versioning

Change field behavior between API versions:

def get_version_attributes(version):
    if version == 'v1':
        return {'legacy_id': {'required': True}}
    return {'uuid': {'required': True}}

attributes = get_version_attributes(request.version)
serializer = ResourceSerializer(resource, field_attributes=attributes)

Combining with Other Features

Field attributes work well with other dynamic features:

serializer = BlogPostSerializer(
    post,
    fields=['id', 'title', 'content'],
    field_attributes={
        'content': {'write_only': True}
    },
    rename_fields={'id': 'post_id'}
)

Error Handling

Invalid attribute dictionaries raise DynamicSerializerConfigError
Non-existent fields are silently ignored
Invalid attribute values raise standard DRF validation errors