Dynamically create classes- Python

Question

I'm trying to figure out what would be the best way to create classes in a dynamic manner based on the contents of a JSON file. So for example, here's a snippet from the JSON file:

{
"stuff": [{
        "name": "burger",
        "aka": ["cheeseburger", "hamburger"]
    },
    {
        "name": "fries",
        "aka": ["french fries", "potatoes"]
    },
    {
        "name": "meal",
        "items": [{
                "name": "burger",
                "value": "<burger>"
            },
            {
                "name": "fries",
                "value": "<fries>"
            }
        ]
    }

  ]
}

And now based on this JSON, I want classes that represent these objects. So for example, something like:

class Burger:
   def __init__(self):
   self.name = "burger"
   self.aka = ["cheeseburger", "hamburger"]

class Meal:
   def __init__(self):
   self.name = "meal"
   self.burger = Burger()
   self.fries = Fries()

So basically, based on that JSON, I want to be able to create classes that represent the same attributes and relationships that we see in the JSON. Any ideas about the best way to approach this would be appreciated!

I've done something similar with mapping FileMaker schema to classes. I just used the attributes to write out a file and then load that file. I imagine you could do pretty much the same. — Keith John Hutchison
– Keith John Hutchison, Commented Jun 14, 2019 at 5:02
Why would you want to write code in JSON? Why not just write the classes ... you know like a .py file — rdas
– rdas, Commented Jun 14, 2019 at 5:03
@rdas I'm not writing the code in JSON, the JSON already exists and the idea is to be able to use that to create the class — David West
– David West, Commented Jun 14, 2019 at 5:04
this question was asked before and answered: for example stackoverflow.com/questions/40336305/… — Radosław Cybulski
– Radosław Cybulski, Commented Jun 14, 2019 at 5:04

Radosław Cybulski · Accepted Answer · 2019-06-14 05:16:49Z

2

Assuming json variable contains your json data try this:

for d in json:
    name = d.pop('name')
    t = type(name, (object,), d)

What it does is to call type, which will create new type in python (exactly the same as if you did class name, which correct name set to content of name variable, with base class object and attributes in d. Variable t will contain class object you want.

answered Jun 14, 2019 at 5:16

Radosław Cybulski

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