[Django]-Returning pure Django form errors in JSON

by

26👍

✅

Got it after a lot of messing around, testing different things. N.B. I’m not sure whether this works with internationalization as well. This also takes the first validation error for each field, but modifying it to get all of the errors should be rather easy.

return json_response({ 'success' : False,
                       'errors' : [(k, v[0].__unicode__()) for k, v in form.errors.items()] })
👤Deniz Dogan

37👍

This appears to have been improved. The following works in Django 1.3:

return json_response({
    'success': False,
    'errors': dict(form.errors.items()),
})

No need for __unicode__ or lazy translation any more. This also gives a full array of errors for each field.

👤SystemParadox

32👍

For Django 1.7+ use Form.errors.as_json() or something like this:

errors = {f: e.get_json_data() for f, e in form.errors.items()}
return json_response(success=False, data=errors)
👤lampslave

4👍

The issue here is that error message are lazy translation object.
The docs do mention this:

Just make sure you’ve got ensure_ascii=False and use a LazyEncoder.

👤Arthur Debert

1👍

We can do this:

import simplejson as json

errors = json.dumps(form.errors)
return HttpResponse(errors, mimetype='application/json')
👤0077cc

1👍

json.dumps can’t serialize django’s proxy function (like lazy translations).

As documented you should create a new Encoder class:

import json
from django.utils.functional import Promise
from django.utils.encoding import force_text
from django.core.serializers.json import DjangoJSONEncoder

class LazyEncoder(DjangoJSONEncoder):
    def default(self, obj):
        if isinstance(obj, Promise):
            return force_text(obj)
        return super(LazyEncoder, self).default(obj)

Use the new Encoder like this:

json.dumps(s, cls=LazyEncoder)

That’s all 🙂

👤bjunix

1👍

You should use django in built method.

from django.http import JsonResponse
return JsonResponse(form.errors.as_json())
👤Sawan Chauhan

1👍

I solved it using get_json_data() as follows:

data = form.errors.get_json_data()
return JsonResponse(data, status=400, safe=False)

We get a valid json:

{"amount": [{"message": "Ensure this value is greater than or equal to 100.", "code": "min_value"}]}

See: https://docs.djangoproject.com/en/4.1/ref/forms/api/#django.forms.Form.errors.get_json_data

If we use as_json() like this:

data = form.errors.as_json()
return JsonResponse(data, status=400, safe=False)

We get a string formatted as a json:

"{\"amount\": [{\"message\": \"Ensure this value is greater than or equal to 100.\", \"code\": \"min_value\"}]}"
👤Julian Espinel

Leave a comment