Python JSON encoding


I'm trying to encode data to JSON in Python and I been having a quite a bit of trouble. I believe the problem is simply a misunderstanding.

I'm relatively new to Python and never really got familiar with the various Python data types, so that's most likely what's messing me up.

Currently I am declaring a list, looping through and another list, and appending one list within another:

import simplejson, json
data = [['apple', 'cat'], ['banana', 'dog'], ['pear', 'fish']]

x = simplejson.loads(data)
# >>> typeError: expected string or buffer..

x = simplejson.dumps(stream)
# >>> [["apple", "cat"], ["banana", "dog"], ["pear", "fish"]]
# - shouldn't JSON encoded strings be like: {{"apple":{"cat"},{"banana":"dog"}}

So I either:

  • I don't understand JSON Syntax
  • I don't understand the Pythons JSON module(s)
  • I'm using an inappropriate data type.


JSON uses square brackets for lists ( [ "one", "two", "three" ] ) and curly brackets for key/value dictionaries (also called objects in JavaScript, {"one":1, "two":"b"}).

The dump is quite correct, you get a list of three elements, each one is a list of two strings.

if you wanted a dictionary, maybe something like this:

x = simplejson.dumps(dict(data))
By : Javier

So, simplejson.loads takes a json string and returns a data structure, which is why you are getting that type error there.

simplejson.dumps(data) comes back with

'[["apple", "cat"], ["banana", "dog"], ["pear", "fish"]]'

Which is a json array, which is what you want, since you gave this a python array.

If you want to get an "object" type syntax you would instead do

By : emeryc


import simplejson
data = {'apple': 'cat', 'banana':'dog', 'pear':'fish'}
data_json = "{'apple': 'cat', 'banana':'dog', 'pear':'fish'}"

simplejson.loads(data_json) # outputs data
simplejson.dumps(data) # outputs data_joon

NB: Based on Paolo's answer.

By : Tom Leys

This video can help you solving your question :)
By: admin