Converting Nested Json into Python object

Question

I have nested json as below

{
"product" : "name",
"protocol" : "scp",
"read_logs" : {
    "log_type" : "failure",
    "log_url" : "htttp:url"
    }
}

I am trying to create Python class object with the below code.

import json
class Config (object):
    """
    Argument: JSON Object from the configuration file.
    """
   def __init__(self, attrs):
        if 'log_type' in attrs:
            self.log_type = attrs['log_type']
            self.log_url = attrs['log_url']
        else:
           self.product = attrs["product"]
           self.protocol = attrs["protocol"]
   def __str__(self):
       return "%s;%s" %(self.product, self.log_type)

   def get_product(self):
        return self.product

   def get_logurl(self):
       return self.log_url

class ConfigLoader (object):
    '''
        Create a confiuration loaded which can read JSON config files
    '''
    def load_config (self, attrs):
        with open (attrs) as data_file:
            config = json.load(data_file, object_hook=load_json)
        return config

def load_json (json_object):
    return Config (json_object)

loader = ConfigLoader()
config = loader.load_config('../config/product_config.json')

print config.get_protocol()

But, the object_hook is invoking the load_json recursively and the Class Config init is being called twice. So the final object that I created does not contain the nested JSON data.

Is there any way to read the entire nested JSON object into a single Python class ?

Thanks

AKX · Accepted Answer · 2017-05-04 07:20:35Z

10

A variation on Pankaj Singhal's idea, but using a "generic" namespace class instead of namedtuples:

import json

class Generic:
    @classmethod
    def from_dict(cls, dict):
        obj = cls()
        obj.__dict__.update(dict)
        return obj

data = '{"product": "name", "read_logs": {"log_type": "failure", "log_url": "123"}}'

x = json.loads(data, object_hook=Generic.from_dict)
print(x.product, x.read_logs.log_type, x.read_logs.log_url)

answered May 4, 2017 at 7:20

AKX

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Comments

Pankaj Singhal · Accepted Answer · 2017-05-04 07:25:08Z

4

namedtuple & object_hook can help create a one-liner:

# Create an object with attributes corresponding to JSON keys.
def json_to_obj(data): return json.loads(data, object_hook=lambda converted_dict: namedtuple('X', converted_dict.keys())(*converted_dict.values()))

OR Create a more readable function like below:

def _object_hook(converted_dict): return namedtuple('X', converted_dict.keys())(*converted_dict.values())
def json_to_obj(data): return json.loads(data, object_hook=_object_hook)

Below is the code snippet to use it:

import json
from collections import namedtuple

data = '{"product": "name", "read_logs": {"log_type": "failure", "log_url": htttp:url}}'

x = json_to_obj(data)
print x.product, x.read_logs.log_type, x.read_logs.log_url

NOTE: Check out namedtuple's rename parameter.

edited May 4, 2017 at 7:25

answered May 4, 2017 at 7:16

Pankaj Singhal

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1 Comment

AKX Over a year ago

Using namedtuples isn't the semantically best option, not to mention creating new namedtuples is fairly slow due to class creation.

Jane Cao · Accepted Answer · 2019-02-11 22:29:36Z

I wrote a simple DFS algorithm to do this job.

Convert nested item as a flat dictionary. In my case, I joined the keys of json item with a dash.

For example, nested item { "a":[{"b": "c"}, {"d":"e"}] } will be transformed as {'a-0-b': 'c', 'a-1-d': 'e'}.

def DFS(item, headItem, heads, values):
    if type(item) == type({}):
        for k in item.keys():
            DFS(item[k], headItem + [k], heads, values)
    elif type(item) == type([]):
        for i in range(len(item)):
            DFS(item[i], headItem + [str(i)], heads, values)
    else:
        headItemStr = '-'.join(headItem)
        heads.append(headItemStr)
        values.append(item)
    return


def reduce(jsonItem):
    heads, values = [], []
    DFS(jsonItem, [], heads, values)
    return heads, values


def json2dict(jsonItem):
    head, value = reduce(jsonItem)
    dictHeadValue = { head[i] : value[i] for i in range(len(head))}
    return dictHeadValue

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