How to retrieve foreign key field in Django rest framework?

I think you need custom field, try this serializer:

class TrackSerializer(serializers.ModelSerializer):
    class Meta:
        model = Track
        fields = ('title', 'artist','artist_name')

    artist_name = serializers.SerializerMethodField('get_artists_name')

    def get_artists_name(self, obj):
        return obj.artist.name

It produce something like this.

[
    {
        "title": "Don't let me down",
        "artist": 2,
        "artist_name": "The Beatles"
    },
    {
        "title": "Summertime",
        "artist": 1,
        "artist_name": "Ella Fitzgerald"
    }
]

Try this serializer,

class ArtistSerializer(serializers.ModelSerializer):

    class Meta:
        model = Artist
        fields = '__all__' # or array of fieldnames like ['name_1', 'name_2']

class TrackSerializer(serializers.ModelSerializer):
    artist = ArtistSerializer()

    class Meta:
        model = Track
        fields = ('title', 'artist')

Inorder to retrieve Artist details, which is a ForeignKey model, you need to use a nested serializer in django-rest-framework.

By using the TrackSerializer with a nested ArtistSerializer, the retrieved data would look something like this,

{
    "title": "Some_Title",
    "artist": {
                   "id": 2, #or id of the artist.
                   "name": "Artist_name"
               }
}

As you can see in the official django rest framework documentations You should define a serializer field for nested items

First create your Artist (nested item) serializer

class ArtistSerializer(serializers.ModelSerializer):

    id = serializers.IntegerField(read_only=True)
    name = serializers.CharField()

    class Meta:
        model = Artist
        fields = ('id', 'name')

Then you can use it on related model serializers

class TrackSerializer(serializers.ModelSerializer):
    artist = ArtistSerializer()

    class Meta:
        model = Track
        fields = ('title', 'artist')

In the current version of DRF you can simply do this

class TrackSerializer(serializers.ModelSerializer):
    
    artist = serializers.StringRelatedField()

    class Meta:
        model = Track
        fields = '__all__'

StringRelatedField may be used to represent the target of the relationship using its __str__ method.

REF