Question 109574 in Json Question posted in
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Create an object from a json value

I have a json file (estate.json) that looks like this:

{
  "type": "FeatureCollection",
  "features": [
    {
      "type": "Feature",
      "id": "724543e2-bd9d-4bef-b9d6-a3ae73d330b7",
      "properties": {
        "objektidentitet": "724543e2-bd9d-4bef-b9d6-a3ae73d330b7",
        "adressplatsattribut": {
          "adressplatstyp": "Gatuadressplats",
          "insamlingslage": "Infart"
        }
      }
    },
    {
      "type": "Feature",
      "id": "1209dd85-d454-46be-bf9c-f2472095fcdc",
      "properties": {
        "objektidentitet": "1209dd85-d454-46be-bf9c-f2472095fcdc",
        "adressplatsattribut": {
          "adressplatstyp": "Gatuadressplats",
          "insamlingslage": "Byggnad"
        }
      }
    },
    {
      "type": "Feature",
      "id": "e12ee844-c138-4f21-95cc-9254e78721d0",
      "properties": {
        "objektidentitet": "e12ee844-c138-4f21-95cc-9254e78721d0",
        "adressplatsattribut": {
          "adressplatstyp": "Gatuadressplats",
          "insamlingslage": "Infart"
        }
      }
    }
  ]
}

With the following lines:

f = open('estate.json')
d = json.load(f)

for id in d['features']:
    print(id['id'])

I can print the values from the keys ‘objektidentitet’ as:

724543e2-bd9d-4bef-b9d6-a3ae73d330b7
1209dd85-d454-46be-bf9c-f2472095fcdc
e12ee844-c138-4f21-95cc-9254e78721d0

I need to use these values in the upcoming step.
I believe that I need to create objects or variables for them?

I have tried creating classes (but I cant seem to understand them):

class obj(object):
    def __init__(self, d):
        for k, v in d.items():
            if isinstance(k, (list, tuple)):
                setattr(self, k, [obj(x) if isinstance(x, dict) else x for x in v])
            else:
                setattr(self, k, obj(v) if isinstance(v, dict) else v)

I have tried using recordclass and

def dict_to_class(class_name: Any, dictionary: dict) -> Any:
    instance = class_name()
    for key in dictionary.keys():
        setattr(instance, key, dictionary[key])
    return instance
Tags:

3

Answers


  1. 0

    I need to use these values in the upcoming step. I believe that I
    need to create objects or variables for them? I have no idea where to
    start, I have been googling this for three months and nothing seem to
    match my dilemma?

    Consider just tossing those values in a list, if you want to keep them separate from the json object:

    d = json.loads('''{
  "type": "FeatureCollection",
  "features": [
    {
      "type": "Feature",
      "id": "724543e2-bd9d-4bef-b9d6-a3ae73d330b7",
      "properties": {
        "objektidentitet": "724543e2-bd9d-4bef-b9d6-a3ae73d330b7",
        "adressplatsattribut": {
          "adressplatstyp": "Gatuadressplats",
          "insamlingslage": "Infart"
        }
      }
    },
    {
      "type": "Feature",
      "id": "1209dd85-d454-46be-bf9c-f2472095fcdc",
      "properties": {
        "objektidentitet": "1209dd85-d454-46be-bf9c-f2472095fcdc",
        "adressplatsattribut": {
          "adressplatstyp": "Gatuadressplats",
          "insamlingslage": "Byggnad"
        }
      }
    },
    {
      "type": "Feature",
      "id": "e12ee844-c138-4f21-95cc-9254e78721d0",
      "properties": {
        "objektidentitet": "e12ee844-c138-4f21-95cc-9254e78721d0",
        "adressplatsattribut": {
          "adressplatstyp": "Gatuadressplats",
          "insamlingslage": "Infart"
        }
      }
    }
  ]
}''')

list_of_ids = [feature['id'] for feature in d['features']]
print(list_of_ids)

    ['724543e2-bd9d-4bef-b9d6-a3ae73d330b7', '1209dd85-d454-46be-bf9c-f2472095fcdc', 'e12ee844-c138-4f21-95cc-9254e78721d0']

    Really though, do you need to put them in this separate list variable, when they are already easily accessible inside your json object d?

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  2. 0

    If you wanted to use classes, that would look like this, but it is very unncessary for actually parsing JSON. A dictionary returned by json.load is already a Python object.

    class FeatureCollection:
  def __init__(self, features):
    self.features = features

class Feature:
  def __init__(self, _id, properties):
    self._id = _id
    self.properties = properties

features = []
with open('estate.json') as f:
    d = json.load(f)
    for x in d['features']:
        features.append(Feature(x['id'], x['properties']))
fc = FeatureCollection(features)
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  3. 0

    You don’t need to convert json to object in this case but it is a satisfying way to work with jsons (and dictionary) like an object (like in javascript).

    in your case the answer is quite simple:

    d = json.loads("...")  # or json.load(open("path to json file"))
ids = [i['id'] for i in d['features']]

    now ids is:

    ['724543e2-bd9d-4bef-b9d6-a3ae73d330b7', '1209dd85-d454-46be-bf9c-f2472095fcdc', 'e12ee844-c138-4f21-95cc-9254e78721d0']

    converting json to object-like instance

    If we have a nested dictionary like below or that one in the question

    {
  "a": "a simple string",
  "b": {
    "a": "nested string",
    "b": {
      "c": [
        [
          [1, 2, 3, 4, 5],
          [6, 7, 8, 9, 0]
        ],
        {"a": "test1", "b": "test2", "c": {"d": 1}},
      ]
    },
  },
}

    in python you should write this code:

    d = json.load(...)
d["b"]["b"]["c"][1]["c"]["d"] # -> 1

    but it is more fun to just write:

    d = jsonobj(json.load(...))
d.b.b.c[1].c.d # -> 1

    so the code that I wrote for converting a json to object, is here:

    class jsonobj:
    def __init__(self, d):
        for k, v in d.items():
            self.__setattr__(k, jsonobj.nested_convert(v))

    @classmethod
    def nested_convert(cls, v):
        if isinstance(v, dict):
            return jsonobj(v)
        elif isinstance(v, list):
            return [jsonobj.nested_convert(i) for i in v]
        else:
            return v

    My code aimed to convert json to object but a dictionary in python could be more complex.

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