How to convert dict to class attributes in Python

Question

Instead of using a dict to store and pass data we are going completely OOPS approach of storing the data as class attributes and call the get methods defined according to need.

In Java i was able to achieve this but having some trouble in Python. Any Solution would be helpful.

import json

class InputModel:
    def __init__(self, input_payload):
        self.id1 = input_payload["id1"]
        self.route = RouteModel(input_payload["route"])
        self.id2 = input_payload["id2"]
        self.id3 = input_payload["id3"]
        self.id4 = input_payload["id4"]
        self.id5 = input_payload["id5"]

        def get_id1(self):
            return self.id1

        #similar for other ids


class RouteModel:
    def __init__(self, input_payload_route):
        self.id6 = input_payload_route["id6"]
        self.id7 = input_payload_route["id7"]
       
        def get_id6(self):
            return self.id6

        #similar for other ids
        
        

json_str = '{"id1":"string","route":{"id6":"string","id7":"string"},"id2": "string","id3": "string","id4": "string","id5": "string"}'
json_dict = json.loads(json_str)
im = InputModel(json_dict)
print(im.get_id1())
print(im.get_id6())

not able to access the nested class attributes

You may want to take a look at [`dataclasses`](https://docs.python.org/3/library/dataclasses.html). The reason `im.get_id1()` is not working here is because your methods are indented one level too deep. I should also mention that Python is not Java. Getters and Setters are discouraged as you can just simply use `im.id1`, etc.. If you're looking to access attributes of the nested instance you can just use `im.route.id6`. — Axe319, Jan 03 '22 at 12:02

score 2 · Accepted Answer · answered Jan 03 '22 at 12:05

Seems like you went for 1 extra indent in your class methods, thus you couldn't reach them.

Also, to reach id6 of RouteModel, you had to refer to 'route' first:

import json

class InputModel:
    def __init__(self, input_payload):
        self.id1 = input_payload["id1"]
        self.route = RouteModel(input_payload["route"])
        self.id2 = input_payload["id2"]
        self.id3 = input_payload["id3"]
        self.id4 = input_payload["id4"]
        self.id5 = input_payload["id5"]

    def get_id1(self):
        return self.id1

        #similar for other ids


class RouteModel:
    def __init__(self, input_payload_route):
        self.id6 = input_payload_route["id6"]
        self.id7 = input_payload_route["id7"]
    
    def get_id6(self):
        return self.id6

        #similar for other ids
        
        

json_str = '{"id1":"string","route":{"id6":"string","id7":"string"},"id2": "string","id3": "string","id4": "string","id5": "string"}'
json_dict = json.loads(json_str)
im = InputModel(json_dict)
print(im.get_id1())
print(im.route.get_id6())

Output:

string
string

You can inherit from RouteModel by defining 'class InputModel(RouteModel):' , then your instance of InputModel can be set with id6 and you will be also able to call get_id6 directly : im = InputModel(json_dict) print(im.get_id1()) im.id6 = 'string' print(im.get_id6()) — NSegal, Jan 03 '22 at 12:35

score 1 · Answer 2 · answered Jan 03 '22 at 12:07

1

The problem is that you are only defining get_id* in your local scope, you need to assign it to the instance if you insist on defining it inside the __init__ method.

I minimized your code example to isolate your issue.

class RouteModel:
    def __init__(self):
        self.id6 = "foo"

        def get_id6(self_=self):
            return self_.id6

        self.get_id6 = get_id6

rm = RouteModel()
print(rm.get_id6())

>>> "foo"

answered Jan 03 '22 at 12:07

Mandera

2,647
3
21
26

so basically what i have created can be called as instance variables and not exactly class variables right? I should define the variables outside the init ? – user17090811 Jan 03 '22 at 12:17
1

You're correct, check my old answer [here](https://stackoverflow.com/a/64916195/3936044) where I tried summarizing the terminology – Mandera Jan 03 '22 at 12:22

score 1 · Answer 3 · answered Jan 03 '22 at 23:09

If I understand your question correctly, you want to be able to access the ids directly as attributes, no matter how deep they are nested in the dictionary.
This solution creates the attributes recursively:

import json

class InputModel:
    def __init__(self, payload):
        self.create_attrs(payload)

    def create_attrs(self, d):
        for key, value in d.items():
            # if the value is a dict, call create_attrs recursively
            if isinstance(value, dict):
                self.create_attrs(value)
            else:
                # create an attribute key=value, e.g. id1="string"
                setattr(self, key, value)


json_str = '{"id1":"string","route":{"id6":"string","id7":"string"},"id2": "string","id3": "string","id4": "string","id5": "string"}'
json_dict = json.loads(json_str)
im = InputModel(json_dict)

print(im.id1)
print(im.id6)

score 0 · Answer 4 · answered Jan 04 '22 at 04:38

After going through answers provided, mostly have defined instance attributes and not class attributes.

Correct me if I'm wrong here but I think this is how class attributes are defined right?

import json

class InputModel:
    def __init__(self, input_payload):
        InputModel.id1 = input_payload["id1"]
        InputModel.route = RouteModel(input_payload["route"])
        InputModel.id2 = input_payload["id2"]
        InputModel.id3 = input_payload["id3"]
        InputModel.id4 = input_payload["id4"]
        InputModel.id5 = input_payload["id5"]

        def get_id1():
            return InputModel.id1
        #OR
        #@classmethod
        #def get_id1(cls):
        #    return cls.id1

        #similar for other ids


class RouteModel:
    def __init__(self, input_payload_route):
        RouteModel.id6 = input_payload_route["id6"]
        RouteModel.id7 = input_payload_route["id7"]
       
        def get_id6():
            return RouteModel.id6

        #similar for other ids
        
        

json_str = '{"id1":"string","route":{"id6":"string","id7":"string"},"id2": "string","id3": "string","id4": "string","id5": "string"}'
json_dict = json.loads(json_str)

InputModel(json_dict)
print(InputModel.get_id1())
print(InputModel.route.get_id6())
print(RouteModel.get_id6())

How to convert dict to class attributes in Python

4 Answers4