Returning pure Django form errors in JSON
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13-09-2019 - |
Question
I have a Django form which I'm validating in a normal Django view. I'm trying to figure out how to extract the pure errors (without the HTML formatting). Below is the code I'm using at the moment.
return json_response({ 'success' : False,
'errors' : form.errors })
With this, I get the infamous proxy object error from Django. Forcing each error into Unicode won't do the trick either, because then each of the errors' __unicode__
method will be called effectively HTML-izing it.
Any ideas?
EDIT:
For those interested, this is the definition of json_response
:
def json_response(x):
import json
return HttpResponse(json.dumps(x, sort_keys=True, indent=2),
content_type='application/json; charset=UTF-8')
Solution 2
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()] })
OTHER TIPS
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.
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)
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.
We can do this:
import simplejson as json
errors = json.dumps(form.errors)
return HttpResponse(errors, mimetype='application/json')
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 :)