Question

I have a class called photo. This class has 4 fields, one of while is called file. This file is of Django’s image field type.

I have a list composed of these image fields. I want to convert this python list in to a json string. If I call json.dumps(listData) on my list, then I get this error:

ImageFieldFile: photos/KObtu.jpg.

This seems sensible. The system represents the image field as a string that is not valid json. How can I override this output string? Alternatively, Is there a better way to do this?

Answer 1

You can create a custom JSON Encoder class that knows how to encode ImageFieldFile:

import json
from django.db.models.fields.files import ImageFieldFile

class EnhancedJSONEncoder(json.JSONEncoder):
    """
    JSONEncoder subclass that knows how to encode Django "ImageFieldFile"s.
    """

    def default(self, o):
        if isinstance(o, ImageFieldFile):
            # Treat ImageFieldFile as a unicode string
            return super(EnhancedJSONEncoder, self).default(unicode(o))
        else:

            return super(EnhancedJSONEncoder, self).default(o)

You would then call json.dumps() as:

json.dumps(listData, cls=EnhancedJSONEncoder))

This assumes you’re wanting ImageFieldFile to be represented as a string