how to avoid eval in python for string conversion?

问题

I'm confronted with an "eval" problem and I would like your advice, I know eval is wrong and I wish to avoid it but I don't know how...

I have some python objects stored in a database, they are stored as strings and I transform them into actual objects with eval. As an example, my objects could be some simple strings like "[2,1,3,4]" or "[[None,None],None]" -- they correspond to different types of object, they don't follow a common pattern. I have to store them as human-readable objects as they are now.

My problem is how to avoid eval in this case ? I don't want to write a parser for each object.

If I do have to use eval, how do I clean up these strings so that they don't do anything nasty ?

回答1:

Use ast.literal_eval:

In [9]: import ast
In [10]: ast.literal_eval("[2,1,3,4]")
Out[10]: [2, 1, 3, 4]

来源：https://stackoverflow.com/questions/15159971/how-to-avoid-eval-in-python-for-string-conversion