CODEWITHSUNDEEP
pythonjsondjangoserializationdjango-rest-framework
Eugene Lisitsky
Eugene Lisitsky

Reputation: 12875

Django Rest Framework: Serialize data from nested json fields to plain object

I want to serialize non-flat structure to a one flat object. Here's an example of an API call I receive (I cannot control it unfortunately):

{
"webhookEvent": "jira:issue_updated",
"user": {
        "id": 2434,
        "name": "Ben",
    },
"issue": {
      "id": "33062",
      "key": "jira-project-key-111",
      "fields": {
          "summary": "The week ahead",
      },
"changelog": {
    "id": "219580",
    "items": [{
         "field": "status",
         "fieldtype": "jira",
         "from": "10127",
         "fromString": "Submitted",
         "to": "10128",
         "toString": "Staged"
    }]
},
"timestamp": 1423234723378
}

I'd like to serialize it to the models like these:

class Issue(models.Model):
    jira_id = models.IntegerField()
    jira_id = models.CharField()
    summary = models.CharField()

class Change(models.Model):
    issue = models.ForeignKey(Issue)
    timestamp = models.DataTimeField()

As you can see, model Issue's field summary is located on the same object as id and key unlike in JSON data.

My Serializer are next:

    class ChangeSerializer(serializers.ModelSerializer):
        """Receives complex data from jira and converts into objects."""

        issue = JiraIssueSerializer()
        timestamp = TimestampField(source='created_at')

        class Meta:
            model = Change
            fields = ('issue', 'timestamp')

        def create(self, validated_data):
            super(serializers.ModelSerializer, self).create(validated_data=validated_data)
            jira_issue = JiraIssueSerializer(data=validated_data)
            issue = Issue.objects.get(jira_issue)
            self.created_at = datetime.utcnow()
            change = Change(**validated_data)
            return change



    class JiraIssueSerializer(serializers.ModelSerializer):
        """Issue serializer."""
        id = serializers.IntegerField(source='jira_id')
        key = serializers.CharField(source='jira_key')
        summary = serializers.CharField()   ### I want field to work!
        # fields = serializers.DictField(child=serializers.CharField())

        class Meta:
            model = Issue
            fields = ('id', 'key',
               'summary',
            )

        def to_internal_value(self, data):
           # ret = super(serializers.ModelSerializer,   self).to_internal_value(data)
           ret = {}
           # ret = super().to_internal_value(data)
           ret['jira_id'] = data.get('id', None)
           ret['jira_key'] = data.get('key', None)
           jira_issue_fields_data = data.get('fields')
           if jira_issue_fields_data or 1:
               summary = jira_issue_fields_data.get('summary', None)
               ret.update(summary=summary)
            print('to_internal_value', ret)
            return ret

         def to_representation(self, instance):
            ret = {}
            ret = super().to_representation(instance)
            fields = {}
            fields['summary'] = instance.summary
            ret.update(fields=fields)
            print(ret)
            return ret

I works well for fields in issue object in JSON. But how can I add to the JiraIssueSerializer some fields like summary? They are not direct fields of issue object, but located in substrcucture fields. I see these ways:

Next I'd like to parse and save changelog data.

How to deal better with such structures?

Thank you!

Upvotes: 19

Views: 21014

Answers (3)

Danny Vu
Danny Vu

Reputation: 1

Documentation has a good part of dealing with nesting in serialisation.

Basically, you want to create a separate class that has the nested values as follows:

class UserSerializer(serializers.Serializer):
    email = serializers.EmailField()
    username = serializers.CharField(max_length=100)

class CommentSerializer(serializers.Serializer):
    user = UserSerializer()
    content = serializers.CharField(max_length=200)
    created = serializers.DateTimeField()

Upvotes: 0

Eugene Lisitsky
Eugene Lisitsky

Reputation: 12875

Finally, solution was found in tests of django-rest-framework.
https://github.com/tomchristie/django-rest-framework/blob/master/tests/test_serializer.py#L149

You may easily define nested serializers which will act as a containers and extract data to your plain object. Like so:

    class NestedSerializer1(serializers.Serializer):
        a = serializers.IntegerField()
        b = serializers.IntegerField()

    class NestedSerializer2(serializers.Serializer):
        c = serializers.IntegerField()
        d = serializers.IntegerField()

    class TestSerializer(serializers.Serializer):
        nested1 = NestedSerializer1(source='*')
        nested2 = NestedSerializer2(source='*')

    data = {
        'nested1': {'a': 1, 'b': 2},
        'nested2': {'c': 3, 'd': 4}
     }

     serializer = TestSerializer(data=self.data)
     assert serializer.is_valid()

     assert serializer.validated_data == {
        'a': 1, 
        'b': 2,
        'c': 3, 
        'd': 4
    }

Upvotes: 23

djq
djq

Reputation: 15298

I would suggest you create your own custom serializer to receive the data. You can do this like so:

from rest_framework import serializers

class MySerializer(serializers.Serializer):
    """
    Custom serializer
    """
    id = serializers.IntegerField(read_only=True)
    name = serializers.CharField()


    def create(self, validated_data):
        """Create a new object"""
        validated_data['custom_value'] = 0 # you can manipulate and restructure data here if you wish
        return MyModel.objects.create(**validated_data)

You can then manipulate the data as you wish in the create() function. You could also create nested custom serializers to parse this data.

Upvotes: 2

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