Additional field while serializing django rest framework

Question

I am a newbie to django rest framework and have created a sample Employee model.

My models.py:

class Employees(models.Model):
    created = models.DateTimeField(auto_now_add=True)
    first_name = models.CharField(max_length=100)
    last_name = models.CharField(max_length=100)

My serializers.py:

class EmployeeSerializer(serializers.Serializer):
    class Meta:
        model = Employees
        fields = ('first_name','last_name')

This works fine but I want an additional field full_name, which will be first_name + last_name.

How do I define this new field full_name in my serializers.py?

Denis Cornehl · Accepted Answer · 2021-11-17 07:22:20Z

126

I see two ways here (I prefer the first way since you can reuse it in other parts of the app):

add a calculated property to your model and add it to your serializer by using a readonly field with source=

# models.py
class Employees(models.Model):
    created = models.DateTimeField(auto_now_add=True)
    first_name = models.CharField(max_length=100)
    last_name = models.CharField(max_length=100)

    @property
    def full_name(self):
        return self.first_name + self.last_name

# serializers.py
class EmployeeSerializer(serializers.ModelSerializer):
    full_name = serializers.Field(source='full_name')

    class Meta:
        model = Employees
        fields = ('first_name','last_name', 'full_name')

by using SerializerMethodField (your model unchanged)

class EmployeeSerializer(serializers.ModelSerializer):
    full_name = serializers.SerializerMethodField('get_full_name')

    def get_full_name(self, obj):
        return obj.first_name + obj.last_name

    class Meta:
        model = Employees
        fields = ('first_name','last_name', 'full_name')

edited Nov 17, 2021 at 7:22

answered Mar 27, 2014 at 5:19

Denis Cornehl

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4 Comments

Anatoly Scherbakov Over a year ago

For me, using serializers.Field gave an error. serializers.ReadOnlyField does work if to_representation is not defined and the view is read-only.

Pynchia Over a year ago

I have just had the same problem (I am not serializing a Django model, but another plain class) and after having banged my head on it for a while I found out that it works fine if you use full_name = serializers.ReadOnlyField(), i.e. discarding the source parameter altogether. As the documentation says about the source parameter: it defaults to the name of the field. Ans it works even if it's a method (or a property)

blueFast Over a year ago

For me (django 1.11.13) there is no need to declare the field in the serializer, just declare it in the Model and list it in the Meta.fields.

ocodo Over a year ago

Note: full_name = serializers.SerializerMethodField() will automatically resolve to def get_full_name(self, obj):. Only specify the method name if it doesn't follow the naming style: get_${field_name}

Yeo · Accepted Answer · 2016-03-07 11:10:00Z

Provided that the Employee is a login user, then most of us will use django.auth.User, I will share how Employee can be implemented as another Profile (extension of django User). Also with the addition of full_name.read_only, first_name.write_only, and last_name.write_only

# models.py
class Employee(models.Model):
    """User Profile Model"""
    user = models.OneToOneField('auth.User')

# serializers.py
class EmployeeSerializer(serializers.HyperlinkedModelSerializer):
    username = serializers.CharField(source='user.username')
    email = serializers.EmailField(source='user.email')

    first_name = serializers.CharField(
            source='user.first_name', write_only=True)
    last_name = serializers.CharField(
            source='user.last_name', write_only=True)
    name = serializers.CharField(
            source='user.get_full_name', read_only=True)


    class Meta:
        model = Employee
        fields = (
            'url', 'username', 'email',
            'first_name', 'last_name', 'name')
        depth = 1

aiven · Accepted Answer · 2018-01-19 15:41:00Z

5

SerializerMethodField works fine, and we can also store data in serializer object and let method get_field_name use that.

Example:

class MySerializer(serializers.ModelSerializer):
    statistic = serializers.SerializerMethodField()

    def __init__(self, instance=None, data=serializers.empty, statistic=None, **kwargs):
        super(MySerializer, self).__init__(instance=instance, data=data, **kwargs)
        self.statistic = statistic

    def get_statistic(self, obj):
        if self.statistic is None:
            return serializers.empty
        return self.statistic.get(obj.id, {})

edited Jan 19, 2018 at 15:41

aiven

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answered Jun 14, 2016 at 13:39

Craynic Cai

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