Python: Prevent python from indexing array. list indices must be integers

Question

I've tried researching this with no luck so far. I'm new to python so my apologies I'm sure there's an easy solution to this.

local obj = {
    'button1': [100, 750],
    'button2': {
        'loc': [100, 1750],
        'returns': 2
     }
}

I want some objects to have an extra property of 'returns'. If I'm looping through the object programmatically I have to check that the 'loc' array exists if I want to access it.

if obj[element]['loc'] is not None:
   # get array w obj[element]['loc']
else:
   # get array w obj[element]

The problem is that I get an error:

# list indices must be integers
TypeError: list indices must be integers, not str

I understand why, it's because 'button1' is an array so python starts the lookup index operation, but finds a string instead of an int. However, I need that bracket to search for my ['loc'] property on my next object. I also know that you can't use the '.' operator to index properties in python so I can't do that either...

How could I check if a property exists without it trying to index the previous object's array.

Answer 1

if isinstance(obj[element], dict) and 'loc' in obj[element]:

Alternatively, you can use try ... except to catch the exception:

try:
    # do something with obj[element]['loc']
except TypeError:
    pass