python - Converting string to ordered dictionary?

Question

I have a string which basically contains a bunch of JSON formatted text that I'd ultimately like to export to Excel in "pretty print" format with the proper indentations for nesting, etc.

It's imperative that the original order of key/values is retained for readability purposes. My thought process to accomplish what I want is to

a) use something like eval to convert the string to a dictionary and b) use OrderedDict from the collections library to keep the order intact.

However I'm not getting the expected result:

In [21]: json_string = str({"id":"0","last_modified":"undefined"})
In [22]: OrderedDict(eval(json_string))
Out[23]: OrderedDict([('last_modified', 'undefined'), ('id', '0')])

I also haven't quite figured out yet how I'm going to write the output to excel in pretty print format, but I'd hope that'd be the comparatively easy part!

Answer 1

You can use the object_pairs_hook argument to JSONDecoder to change the decoded dictionaries to OrderedDict:

import collections
import json

decoder = json.JSONDecoder(object_pairs_hook=collections.OrderedDict)

json_string = '{"id":"0","last_modified":"undefined"}'
print decoder.decode(json_string)
json_string = '{"last_modified":"undefined","id":"0"}'
print decoder.decode(json_string)

This prints:

OrderedDict([(u'id', u'0'), (u'last_modified', u'undefined')])
OrderedDict([(u'last_modified', u'undefined'), (u'id', u'0')])