Django Rest Framework - How to restructure json response?

Question

I am using Django Rest Framework (along with rest_framework_mongoengine) and overriding to_representation() of my serializer to send back my own custom JSON object. Everything is working fine but the order of JSON fields is messed up. Please tell me how to reorder/restructure the JSON object being sent back. The serializer looks like this:

class PharmacySerializer(DocumentSerializer):

    bank_account = serializers.DictField(child=serializers.CharField(), required=False)



    class Meta:

        model = Pharmacy

        fields = (

            'id', 'name', 'email', 'mobile', 'address_line_1', 'address_line_2',

            'city', 'state', 'zip', 'created_by', 'created_on', 'last_updated_by', 'license_number',

            'bank_account', 'last_updated_on', 'is_email_verified', 'is_mobile_verified', 'is_active')

        read_only_fields = ('created_by', 'created_on', 'last_updated_by', 'last_updated_on', 'is_active')



    def to_representation(self, pharmacy):

        return {

            'id': str(pharmacy.id),

            'name': pharmacy.name,

            'email': pharmacy.email,

            'mobile': pharmacy.mobile,

            'address_line_1': pharmacy.address_line_1,

            'address_line_2': pharmacy.address_line_2,

            'city': pharmacy.city,

            'state': pharmacy.state,

            'zip': pharmacy.zip,

            'created_by': pharmacy.created_by,

            'created_on': pharmacy.created_on,

            'last_updated_by': pharmacy.last_updated_by,

            'license_number': pharmacy.license_number,

            'bank_account': {

                'bank_name': pharmacy.bank_account.bank_name,

                'account_number': pharmacy.bank_account.account_number,

                'account_type': pharmacy.bank_account.account_type

            },

            'last_updated_on': pharmacy.last_updated_on,

            'is_email_verified': pharmacy.is_email_verified,

            'is_mobile_verified': pharmacy.is_mobile_verified,

            'is_active': pharmacy.is_active

        }

And the response that I am getting is:

[

    {

        "city": "City",

        "name": "Some Pharmacy",

        "zip": "778372",

        "mobile": "9880082229",

        "license_number": "SP22",

        "is_mobile_verified": false,

        "is_active": true,

        "created_on": "2016-06-18T19:01:02.901",

        "created_by": null,

        "email": "somepharmacy@gmail.com",

        "state": "State",

        "last_updated_by": null,

        "is_email_verified": false,

        "last_updated_on": "2016-06-18T19:01:02.901",

        "address_line_2": null,

        "id": "57659a6ea3b6561c0f20265e",

        "bank_account": {

            "bank_name": "HSBC",

            "account_type": "Savings",

            "account_number": "663822553"

        },

        "address_line_1": "Address"

    }

]

I want it to be in the same order as the return dict of to_representation()

Answer 1

If you want to maintain order of response keys, you can use an OrderedDict. But there is one thing you should remember about OrderedDicts:

OrderedDict maintains order only while insertion of keys. The order gets lost while initializing with kwargs.

From Python docs:

The OrderedDict constructor and update() method both accept keyword arguments, but their order is lost because Python’s function call semantics pass-in keyword arguments using a regular unordered dictionary.

You need to first create an OrderedDict instance and then add keys one by one.

from collections import OrderedDict

def to_representation(self, pharmacy):
    ret = OrderedDict() # initialize on ordereddict

    # insert keys one by one in desired oreder
    ret['id'] = str(pharmacy.id)
    ret['name'] = pharmacy.name
    ret['email'] = pharmacy.email
    ret['mobile'] = pharmacy.mobile
    ret['address_line_1'] = pharmacy.address_line_1
    ret['address_line_2'] = pharmacy.address_line_2
    ret['city'] = pharmacy.city
    ret['state'] = pharmacy.state
    ret['zip'] = pharmacy.zip
    ret['created_by'] = pharmacy.created_by
    ret['created_on'] = pharmacy.created_on
    ret['last_updated_by'] = pharmacy.last_updated_by
    ret['license_number'] = pharmacy.license_number
    ret['bank_account'] = {
        'bank_name' = pharmacy.bank_account.bank_name
        'account_number' = pharmacy.bank_account.account_number
        'account_type' = pharmacy.bank_account.account_type
    }
    ret['last_updated_on'] = pharmacy.last_updated_on
    ret['is_email_verified'] = pharmacy.is_email_verified
    ret['is_mobile_verified'] = pharmacy.is_mobile_verified
    ret['is_active'] = pharmacy.is_active

    return ret

Note: Another option is to use EmbeddedDocumentSerializer for bank_account field. Then you won't need to override the to_representation() method.

Django Rest Framework - How to restructure json response?

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