heaVenShaker heaVenShaker - 5 months ago 45
Python Question

Django Rest Framework - How to restructure json response?

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

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.