Serializers

Model Serializer

Basic usage of ModelSerializer

Need to provide one of the attributes fields or exclude
Prefer to use Third party packages instead of writing on your own
Use select_related and prefetch_related to improve queries performance

# serializers.py
from res_framework import serializers

# Yes
class AccountSerializer(serializers.ModelSerializer):
    class Meta:
        model = Account
        fields = ['id', 'account_name', 'users', 'created']

# Yes
class AccountSerializer(serializers.ModelSerializer):
    class Meta:
        model = Account
        fields = '__all__'

# Yes
class AccountSerializer(serializers.ModelSerializer):
    class Meta:
        model = Account
        exclude = ['users']

ModelControllerSerializer

If your model extends from AbstractModelController use ModelControllerSerializer

# serializers.py
from model_controller import serializers as mc_serializers
from res_framework import serializers


# Yes 
class AccountSerializer(mc_serializers.ModelControllerSerializer):
    pass

# No
class AccountSerializer(serializers.ModelSerializer):
    def create(self, validated_data):
        user = self.context['request'].user

        validated_data['created_user'] = user
        validated_data['updated_user'] = user

        return super().create(validated_data)

    def update(self, instance, validated_data):
        user = self.context['request'].user

        validated_data['updated_user'] = user

        return super().update(instance, validated_data)

Fields

SerializerMethodField

If it's just a property of object you can use source instead

# serializers.py
from rest_framework import serializer

# Yes
class ProfileSerializer(serializers.ModelSerializer):
    username = serializers.CharField(source='user.username')

# No
class ProfileSerializer(serializers.ModelSerializer):
    username = serializers.SerializerMethodField()

    def get_username(self, obj):
        return obj.username

HiddenField

Use HiddenField to provide a predefined value

from django.utils import timezone
from rest_framework import serializers

# Yes
class EmailSerializer(serializers.ModelSerializer):
    modified = serializers.HiddenField(default=timezone.now)

# No
class EmailSerializer(serializers.ModelSerializer):
    def create(self, validated_data):
        validated_data['modified'] = timezone.now()
        return super().create(validated_data)
    
    def update(self, instance, validated_data):
        validated_data['modified'] = timezone.now()
        return super().create(instance, validated_data) 

CreateOnlyDefault

Use CreateOnlyDefault to set a default argument during create operations

from rest_framework import serializers

# Yes
class EmailSerializer(serializers.ModelSerializer):
    owner = serializers.CreateOnlyDefault(default=serializers.CurrentUserDefault())

# No
class EmailSerializer(serializers.ModelSerializer):
    def create(self, validated_data):
        owner = self.context['request'].user
        return super().create(validated_data))

Validation

Prefer to use DRF Validators over custom validation functions

Field level Validation

Your validate_<field_name> methods should return a validated value or raise serializers.ValidationError

from rest_framework import serializers

# Yes
class BlogPostSerializer(serializers.Serializer):
    title = serializers.CharField(max_length=100)
    content = serializers.CharField()

    def validate_title(self, value):
        if 'django' not in value.lower():
            raise serializers.ValidationError("Blog post is not about Django")
        return value


# No 
class BlogPostSerializer(serializers.Serializer):
    title = serializers.CharField(max_length=100)
    content = serializers.CharField()

    def validate_title(self, value):
        if 'django' not in value.lower():
            raise ValueError("Blog post is not about Django")
        return value

Object level validation

Do not manipulate the data while doing object level validation

from rest_framework import serializers

# Yes
class EventSerializer(serializers.Serializer):
    description = serializers.CharField(max_length=100)
    start = serializers.DateTimeField()
    finish = serializers.DateTimeField()

    def validate(self, data):
        if data['start'] > data['finish']:
            raise serializers.ValidationError("finish must occur after start")
        return data

# No
class EventSerializer(serializers.Serializer):
    description = serializers.CharField(max_length=100)
    start = serializers.DateTimeField()
    finish = serializers.DateTimeField()

    def validate(self, data):
        data['description'] = 'some description'
        if data['start'] > data['finish']:
            raise serializers.ValidationError("finish must occur after start")
        return data

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