Understanding the to_representation and to_internal_value Methods in the Django Rest Framework
Tags: programming, django, python, webdev
Published: 2023-06-05 06:06:38

The Django Rest Framework makes it simpler to create APIs with Django. It offers a variety of powerful capabilities that enable it straightforward to convert Python objects into a format that can be broadcast over the internet, like serializers. The two most important options provided by serializers are **`to_internal_value`** and **`to_representation`**. We'll look at these two methods in this article and see how the Django Rest Framework applies them.

What are **`to_representation`** and **`to_internal_value`**?

Serializers in the Django Rest Framework offer two methods: **`to_representation`** and **`to_internal_value`**. These techniques are used to translate between an object's internal representation and its serialised representation.

The **`to_representation`** method is used to convert the internal representation of an object into its serialized representation. This is used when serializing an object to be sent over the wire.

The **`to_internal_value`** method is used to convert the serialized representation of an object back into its internal representation. This is used when deserializing an object that has been received over the wire.

How are **`to_representation`** and **`to_internal_value`** used?

Let's say we have a **`Person`** model with the following fields:

```
class Person(models.Model):
    first_name = models.CharField(max_length=50)
    last_name = models.CharField(max_length=50)
    birthdate = models.DateField()
```

We can create a serializer for this model using Django Rest Framework like this:

```
class PersonSerializer(serializers.ModelSerializer):
    class Meta:
        model = Person
        fields = ['first_name', 'last_name', 'birthdate']
```

Now, let's say we want to customize the serialized representation of the **`Person`** object. We can do this by defining a **`to_representation`** method in the serializer:

```
class PersonSerializer(serializers.ModelSerializer):
    class Meta:
        model = Person
        fields = ['first_name', 'last_name', 'birthdate']

    def to_representation(self, instance):
        data = super().to_representation(instance)
        data['full_name'] = f"{instance.first_name} {instance.last_name}"
        return data
```

In this example, we are adding a **`full_name`** field to the serialized representation of the **`Person`** object. We do this by calling the **`super().to_representation(instance)`** method to get the default serialized representation of the object, and then add our own custom field to the data.

Now, let's say we want to customize the deserialization of the **`Person`** object. We can do this by defining a **`to_internal_value`** method in the serializer:

```
class PersonSerializer(serializers.ModelSerializer):
    class Meta:
        model = Person
        fields = ['first_name', 'last_name', 'birthdate']

    def to_internal_value(self, data):
        full_name = data.pop('full_name', None)
        if full_name:
            first_name, last_name = full_name.split()
            data['first_name'] = first_name
            data['last_name'] = last_name
        return super().to_internal_value(data)
```

In this example, we are customizing the deserialization of the **`Person`** object by allowing the user to provide a **`full_name`** field instead of separate **`first_name`** and **`last_name`** fields. We do this by popping the **`full_name`** field from the data, splitting it into **`first_name`** and **`last_name`**, and then adding those fields back to the data. We then call the **`super().to_internal_value(data)`**
 method to get the default internal representation of the object.