Decoding JSON file using python

[Karthik Sharma]

I have the JSON structure shown below and the python code shown below to manipulate the JSON structure.

    import json
    
    json_input = { 
        "msgType": "0",
        "tid": "1",
        "data": "[{\"Severity\":\"warn\",\"Subject\":\"Reporting \",\"Message\":\"tdetails:{\\\"Product\\\":\\\"Gecko\\\",\\\"CPUs\\\":8,\\\"Language\\\":\\\"en-GB\\\",\\\"isEvent\\\":\\\">
        "Timestamp": "1432703193431",
        "Host": "myserver.com",
        "Agent": "Experience",
        "AppName": "undefined",
        "AppInstance": "my_server",
        "Group": "UndefinedGroup"
    }
    
    
    data = json_input['data']
    tdetails = data['Message']
    print('json_input {} \n\ndata {} \n\n tdetails {}\n\n'.format(json_input,data,tdetails))  

I am getting the error.

    Traceback (most recent call last):
      File "test_json.py", line 19, in <module>
        tdetails = data['Message']
    TypeError: string indices must be integers, not str

The JSON structure is valid as shown by http://jsonlint.com/
   I want to be able to access the different fields inside `data` such as `severity`, `subject` and also fields inside `tdetails` such as `CPUs` and `Product`. How do I do this?