Using Django 1.11, Python 2.7, PostGres, and JSONField I'm getting behavior I don't expect.
It seems when JSONField values are initially saved/accessed in memory, they're python "integers", but when saved to the database and then re-accessed, the values are now in string format. *What about how Django handles JSONField string vs integers am I missing here? Whats the best way to get deterministic behavior here? * Am I supposed to always, say, use json.dumps to work with JSON in string format? Should I be converting all JSONField fields into string or integers before trying to manipulate any values in Django? *Example 1 - Basic Problem* Example Model : class ExampleModel(models.Model): external_ids = JSONField(blank=True, null=True, default=dict) My code: new_example = ExampleModel.objects.create() new_example.external_ids[1234] = {} print(new_example.external_ids) Output looks like this : {1234: {}} I can now access values stored like this : In [140]: new_example.external_ids[1234] Out[140]: {} I will now then save the object to the database new_example.save() However, when I go back and try to access the fields again, all integer values in the JSON have been converted into strings, and I cannot access them anymore without getting a KeyError reload_example = ExampleModel.objects.get(id=1) reload_example.external_ids[1234] In [144]: reload_example.external_ids[1234] --------------------------------------------------------------------------- KeyError Traceback (most recent call last) <ipython-input-147-064b4b6a1511> in <module>() ----> 1 reload_example.external_ids[1234] KeyError: 1234 By this time, the integer 1234 has been converted into a string that looks like something like the following : *Why is this?* *In [147]: print(reload_example.external_ids)Out[147]: {u'1234': {}}* Therefore, at this time, I have to do this to access the fields : *Whats the correct way to handle this?* In [160]: reload_example.external_ids[str(1234)] Out[160]: {} *Example 2 - Confusing identical key conflict when model is loaded in memory with both integer and string based keys* In fact, this creates some other interesting problems for me too, where integer keys and string keys get merged together in uncertain order as well. First, I create a new model and save some dictionary down to the JSONField In [164]: example2 = ExampleModel.objects.create() In [165]: example2.external_ids Out[165]: {} In [166]: example2.external_ids[1234] = {'567': '890'} In [167]: example2.save() In [169]: example2.external_ids Out[169]: {1234: {'567': '890'}} *Then I reload the model * In [170]: reload_example2 = ExampleModel.objects.get(id=2) In [171]: reload_example2.external_ids Out[171]: {u'1234': {u'567': u'890'}} *Then I try to replace those values : (I swapped the 567 and the 890)* In [172]: reload_example2.external_ids[1234] = {'890': '567'} *For the time being, now I have two key value pairs in memory for the same key, just that the older data falls under a string instance of the key, and both values can be accessed* In [173]: reload_example2.external_ids Out[173]: {1234: {'890': '567'}, u'1234': {u'567': u'890'}} *After I save and then reload the model, I'm unsure which value gets saved over. (Although in tests it seems like the newest data wins)* In [174]: reload_example2.save() In [175]: reload_example3 = ExampleModel.objects.get(id=2) In [176]: reload_example3.external_ids Out[176]: {u'1234': {u'890': u'567'}} Thanks! Oliver -- You received this message because you are subscribed to the Google Groups "Django users" group. To unsubscribe from this group and stop receiving emails from it, send an email to django-users+unsubscr...@googlegroups.com. To post to this group, send email to django-users@googlegroups.com. Visit this group at https://groups.google.com/group/django-users. To view this discussion on the web visit https://groups.google.com/d/msgid/django-users/bfb08c4e-c6af-4efe-a365-85aadd9d5cfd%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.