Convert list with each element an object of class into json

Question

I have a python list where each element in the list is the object of a class Summershum.Model.File:

message = [
, 
,
,
,
,
,
,
,
,
,
, 
,
, 

]

I am trying to convert this list into json and want to pass it to view for displaying (filename, sha1sum).

I was trying to convert the class object using "json" method: message = [msg.json() for msg in message] But

print message

gives me nothing empty list. What is the correct way of doing it?

Rob Watts · Accepted Answer

Based on the output of dir(message[0]) that you provided, the error is simple - _there is no __json__() method for a summershum.model.File object. So I'm guessing that the relevant section of your code looks like this:

try:
    ...
    message = [msg.__json__() for msg in message]
    print message
    ...
except Exception:
    # Some code, or just "pass"

Because there is no __json__() method, you should be getting an AttributeError. However, it sounds like you were not seeing an exception, which is why I assume there's a try...except block surrounding the code.

With no built-in method to convert the file contents to json, you'll have to use the built-in json module. For example:

>>> import json
>>> jsonString = '{"one":"two"}'
>>> jsonObj = json.loads(jsonString)
>>> jsonObj
{u'one': u'two'}

You'll need to call json.loads and give it the contexts of the file. I'm not sure exactly what you'll need to do that, but based on the available methods I would suggest seeing what the get and tar_file methods give you.

It's also possible that you're just trying to call __json__() too soon - the objects you get from get or tar_file might have a __json__() method.

Convert list with each element an object of class into json

Answers (1)

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