CODEWITHSUNDEEP
django
Houman
Houman

Reputation: 66320

Serialization of an object with foreign key into json

this is in Django:

data = []
data += serializers.serialize("json", conversation_deal)
data += serializers.serialize("json", deal_statuses)
dat = serializers.serialize("json", data)
return HttpResponse(dat)

I would like to save one round trip to the webservice and combine two jsons into one. What I tried to do was to serialize each object into json and add them into an array and serialize them again as json. But it throws an exception.

I also tried to put the two python objects into the array and serialize them all into json, which also failed.

How is this usually done?

Update:

Exception:

str: 'str' object has no attribute '_meta'

Update 2:

I have some more information, and it seems its somehow Django related the way it serializes the objects.

the following works perfectly fine:

deal_statuses = DealStatus.objects.all()        
data = serializers.serialize("json", deal_statuses)
return HttpResponse(data)

but this fails..

conversation_deal = Conversation_Deal.objects.filter(conversation_id__in=call_id)
data = serializers.serialize("json", conversation_deal)
return HttpResponse(data)

This is how Conversation_Deal is modelled:

class Conversation_Deal(models.Model):
    conversation        = models.ForeignKey('Conversation')
    deal                = models.ForeignKey('Deal')
    status              = models.ForeignKey(DealStatus, null=True, blank=True)

I found something related to inherited classes documentation pointing this out why...Even though I am not inheriting, but the same process worked in my case. Hope this helps someone else. I will post this as an answer soon.

Upvotes: 0

Views: 1559

Answers (1)

Houman
Houman

Reputation: 66320

I found the solution.

Literally since Conversation_Deal has a foreignkey to DealStatus class. It needs to know about it during serialization.

all = list(Conversation_Deal.objects.filter(conversation_id__in=call_id)) + list(DealStatus.objects.all())
return HttpResponse(simplejson.dumps(to_json), mimetype='application/json')

Hope this helps somebody else.

Upvotes: 1

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