Question

There maybe (usually is) a better way to do what I’m trying, but I am currently making a list of objects like this:

my_list = [MyObject(d**) for d in db.myobjects.find({...})]

This works great because it creates converts the dictionary objects returned by my database query into “MyObjects”, adding in a bunch of class methods and properties.

How can I do the same thing when the Class name is dynamically inserted at runtime? I can create the classes dynamically using eval() but how can I insert the dictionary objects?

my_list = [eval('FooObject') for d in db.fooobjects.find({...})]  # needs kwargs from dicts

Any help would be awesome.

Answer 1

First, consider using globals() instead of eval(), especially if the class string is from user input.

To your actual question, it works exactly the same way – eval('FooClass') or globals()['FooClass'] gives you the class itself, it doesn’t instantiate it. That means you can instantiate it by calling it, same as if you know its name ahead of time:

globals()['FooClass'](**d)