Python Ast Vs Json For Str To Dict Translation

I have a piece of code that receives a string formatted as a python dictionary '{'a':'1','b':'2',...}' which I need to convert to a proper dictionary. I have tried two approaches,

Solution 1:

Use ast.literal_eval() - it's designed to do what you want. JSON happens to work as the syntax matches, but that isn't something you should rely on.

As to safety, literal_eval() is specifically designed to be safe to use on data from untrusted sources. The first word of the docs, in fact, is 'Safely':

Safely evaluate an expression node or a string containing a Python expression. The string or node provided may only consist of the following Python literal structures: strings, numbers, tuples, lists, dicts, booleans, and None.

This can be used for safely evaluating strings containing Python expressions from untrusted sources without the need to parse the values oneself.

Those that advised you against using it were probably thinking of eval(), which is indeed unsafe.