Python use string variable as index/key for nested list/dict

data = {'virtualInterfaces': [{"interfaceName": "abc", "interfaceState": "online"}, {"interfaceName": "axc", "interfaceState": "online"}, {"interfaceName": "xpto", "interfaceState": "offline"}]}

foo = "['virtualInterfaces'][2]['interfaceState']"

I need to use the var "foo" to get a specific value from data

e.g

data[foo] #should return "offline"

I tried to use eval

value = eval(data + foo)

But didn´t work.
Foo can have any number of nested list/dict

>Solution :

foo contains the literal indexing string, whereas data is not a string, but the dictionary object. So you have to put data in quotes to use eval:

value = eval('data' + foo)