How to validate a json structure in Python3

Question

I am using Python3.5 and Django for a web api.When I refer to input, I refer to a HTTP request parameters. I have a parameter where I am expecting a JSON data which I need to validate before processing further.

I have a base json structure that the input has to be in. Example,

{
  "error": "bool",
  "data": [
      {
        "name": "string",
        "age": "number"
      },
      {
        "name": "string",
        "age": "number"
      },
      ...
    ]
}

The above JSON represents the structure that I want my input to be in. The keys are predefined, and the value represents the datatype of that key that I am expecting. I came across a Python library(jsonschema) that does this validation, but I can't find any documentation where it works with dynamic data. i.e. the objects inside the JSON array 'data' can be of any number, of course this is the most simple scenario I came up with for explaining the basic requirement. In cases like these, how can I validate my json?

The solution here didn't help because it's just checking if the json is proper or not based on the Django model. My json has no relation with Django model. Its a simple json structure. It still doesn't tell me how to validate dynamic object

@AjaySingh No, the solution there, just checking if the json is proper or not based on the Django model. My json has no relation with Django model. Its a simple json structure. It still doesn't tell me how to validate dynamic object. — Parthapratim Neog
– Parthapratim Neog, Commented Mar 23, 2017 at 13:46

Daniel Roseman · Accepted Answer · 2017-03-23 14:49:58Z

7

JSON Schema is a specification for validating JSON; jsonschema is just a Python library that implements it. It certainly does allow you to specify that a key can contain any number of elements.

An example of a JSON Schema that validates your code might be:

{
  "$schema": "http://json-schema.org/draft-04/schema#",
  "type": "object",
  "additionalProperties": false,
  "required": [
    "error",
    "data"
  ],
  "properties": {
    "error": {
      "type": "boolean"
    },
    "data": {
      "type": "array",
      "items": {
        "type": "object",
        "additionalProperties": false,
        "properties": {
          "name": {
            "type": "string"
          },
          "age": {
            "type": "integer"
          }
        }
      }
    }
  }
}

See https://spacetelescope.github.io/understanding-json-schema/ for a good overview

edited Mar 23, 2017 at 14:49

answered Mar 23, 2017 at 14:45

Daniel Roseman

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5 Comments

Parthapratim Neog Over a year ago

This looks legit, I will try it out tomorrow and get back. Thanks!

user6165050 Over a year ago

Shouldn't false be surrounded by quotes?

Daniel Roseman Over a year ago

No, why should it be? It's a Boolean, not a string; the bool values in JavaScript (and json) are true and false.

user6165050 Over a year ago

I was asking because I tried to build the schema to validate against, and false doesn't quite work in Py. :D

Daniel Roseman Over a year ago

If you construct this as a Python dict, you'll need to use Python types, so it will be False. When you dump it to json, it'll be converted to false.

Nathangrad · Accepted Answer · 2017-03-23 13:17:38Z

-1

Take a look into the documentation of Python's JSON API. I believe json.tool is what you're looking for, however there are a couple of other ways to validate JSON using that API.

answered Mar 23, 2017 at 13:17

Nathangrad

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2 Comments

Parthapratim Neog Over a year ago

Lemmi have a look.

123survesh Over a year ago

The json.tool seems to only check if the json is of valid python's json format. The question here is to validate based on a predefined json structure with possible keys and corresponding possible values.

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