Core Arguments of Django Rest Framework Serializer
Published: 2023-12-17 19:00:45



𝗖𝗼𝗿𝗲 𝗔𝗿𝗴𝘂𝗺𝗲𝗻𝘁𝘀 𝗼𝗳 𝗦𝗲𝗿𝗶𝗮𝗹𝗶𝘇𝗲𝗿𝘀 𝗶𝗻 𝗗𝗷𝗮𝗻𝗴𝗼 𝗥𝗲𝘀𝘁 𝗙𝗿𝗮𝗺𝗲𝘄𝗼𝗿𝗸


In Django Rest Framework (DRF), serializers are responsible for converting complex data types such as querysets and model instances to Python data types that can then be easily rendered into JSON, XML, or other content types. They also provide deserialization, allowing parsed data to be converted back into complex types after validating incoming data. To achieve this, serializers use various field classes, each with a set of core arguments that control their behavior. 

Below are core arguments and their purpose:


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𝗿𝗲𝗮𝗱_𝗼𝗻𝗹𝘆
 This argument determines whether a field is used only for serialization and not for deserialization. When set to True, the field will be included in the output representation but ignored for creating or updating an instance. By default, it is set to False.



𝘄𝗿𝗶𝘁𝗲_𝗼𝗻𝗹𝘆
 If set to True, the field can be used for creating or updating an instance but won't be included in the serialized output. This is useful for fields that should not be exposed, like passwords. Its default value is False.



𝗿𝗲𝗾𝘂𝗶𝗿𝗲𝗱
 This argument specifies whether a field must be present in the input data during deserialization. If set to False, the field is not mandatory. Additionally, the attribute or key for this field may be omitted in the serialized output if absent. By default, it is True, but if using ModelSerializer, it can default to False based on the model's field configuration (e.g., blank=True).



𝗱𝗲𝗳𝗮𝘂𝗹𝘁
This provides a default value for the field if no input is given. It can be a static value, a callable, or a function that is evaluated each time the default is accessed. If a default is provided, the field automatically becomes non-required. Note that for partial updates, the default is not used, and when serializing, it's used only if the object attribute or dictionary key is missing.



𝗮𝗹𝗹𝗼𝘄_𝗻𝘂𝗹𝗹
 By setting this argument to True, you allow the field to accept None as a valid value. This doesn't imply a default value for deserialization. The default for allow_null is False.

𝘀𝗼𝘂𝗿𝗰𝗲
 Specifies the attribute used to populate the field. You can use a method (like source='get_absolute_url') or a dotted path to navigate through attributes (source='user . email'). If using dotted notation, it is often prudent to specify a default value to avoid attribute errors during serialization. Special value source='*' means that the entire object should be passed to the field.



𝘃𝗮𝗹𝗶𝗱𝗮𝘁𝗼𝗿𝘀
A list of validator functions that are called on the field's input. They should raise serializers.ValidationError (or Django's ValidationError) if validation fails.





𝗲𝗿𝗿𝗼𝗿_𝗺𝗲𝘀𝘀𝗮𝗴𝗲𝘀
 A dictionary mapping error codes to their respective error messages, allowing for custom error messages.



𝗹𝗮𝗯𝗲𝗹
 A string that serves as a human-readable name for the field, which can be displayed in forms or other interfaces.



𝗵𝗲𝗹𝗽_𝘁𝗲𝘅𝘁
 A description of the field, typically displayed alongside it in forms or other interfaces.



𝗶𝗻𝗶𝘁𝗶𝗮𝗹
 A value used for pre-populating the field in forms. It can also be a callable, just like Django's field initial.



𝘀𝘁𝘆𝗹𝗲
 A dictionary containing rendering options for the field. This can affect how the field is displayed in the browser. Examples include setting input_type for password fields or using a different base template for choice fields.





These core arguments provide the flexibility needed to define the behavior of serializer fields in DRF, ensuring that API representations are precise, secure, and beneficial for both API providers and consumers.



Docs: https://www.django-rest-framework.org/api-guide/fields/#core-arguments



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