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I need to query a model by a JsonField, I want to get all records that have empty value ([]):

I used MyModel.objects.filter(myjsonfield=[]) but it's not working, it returns 0 result though there's records having myjsonfield=[]

0m3r
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mou55
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4 Answers4

5

Use the dunder __exact for this. The __isnull=True does not work because the JSONField is technically not null.

MyModel entries where myjsonfield is empty:

MyModel.objects.include(myjsonfield__exact=[])

MyModel entries where myjsonfield is not empty:

MyModel.objects.exclude(myjsonfield__exact=[])

https://docs.djangoproject.com/en/3.1/ref/models/querysets/#std:fieldlookup-exact

I believe if you've set the default=dict in your model then you should use {} (eg: myjsonfield__exact={}) instead of [] but I haven't tested this.

TheZeke
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  1. Firstly, Django actually recommends that you declare JSONField with immutable/callable default values. For your example:

     class MyModel(models.Model):
     myjsonfield = models.JSONField(null=True, default=list)

  2. Secondly, to query by null JSONField:

     MyModel.objects.filter(myjsonfield__isnull=True)

    To query for fields having default value ([] in your case):

     MyModel.objects.filter(myjsonfield__exact=[])

See https://docs.djangoproject.com/en/4.0/topics/db/queries/#querying-jsonfield for more details and examples.

Ankit Kumar Singh
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JSONfield should be default={} i.e., a dictionary, not a list.

e.barojas
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    No it shouldn't. JSON can be a list or a dict at root level. In Django having it as default={} doesn't return in order of entry. Having it as a list allows some order to it. – James Bellaby Dec 28 '20 at 13:18
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    It can be either. `default=dict` or `default=list` since JSON can be either a dict or a list. Don't set it to actual value of {} or [] and don't actually call the function (eg. `dict()`) though. Set it to the name of the function that produces the value. It will be called when it needs to set a default. – TheZeke Mar 04 '21 at 22:21
-1

Try MyModel.objects.filter(myjsonfield='[]').

zxzak
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