Generate json schema and validate json against the schema

Question

How do I generate a JSON schema in Python for the below JSON and validate every json against the schema?

Requirements:

• There is a type which can be CSV or JSON or JSON
• There is a list of properties.
• Each property has a key which is a column name and the value is a dict which defines the column attributes. The first column col1 has an attributes type string and corresponds to index zero.

    {
            "type": "csv/json",
            "properties": {
                "col1": {
                    "type": "string",
                    "index":0
                },
                "col2": {
                    "type": "number",
                    "index":1
                },....
            }
        }

How do I generate a JSON schema for this json?

Sample Valid json

{
    "type": "csv",
    "properties": {
        "header1": {
            "type": "string",
            "index":0
        },
        "header2": {
            "type": "number",
            "index":1
        }   
    }
}

Sample invalid json (because the type is bool for header 1 and misses index attribute)

{
    "type": "CSV",
    "properties": {
        "header1": {
            "type": "bool"
        },
        "header2": {
            "type": "number",
            "index":1
        }   
    }
}

Answer 1

You can use jsonschema library for generate a JSON schema in Python and validate against the schema.

Install jsonschema first by pip install jsonschema

Now you can use jsonschema for generate a JSON schema for your JSON structure and validate it.

for eg:

import jsonschema
from jsonschema import validate

# Define the JSOn schema
schema = {
    "type": "object",
    "properties": {
        "type": {"enum": ["csv", "json"]},
        "properties": {
            "type": "object",
            "patternProperties": {
                "^.*$": {
                    "type": "object",
                    "properties": {
                        "type": {"type": "string"},
                        "index": {"type": "integer"},
                    },
                    "required": ["type", "index"],
                }
            },
            "additionalProperties": False,
        },
    },
    "required": ["type", "properties"],
}

# Sample valid JSON
valid_json = {
    # Your Sample valid JSON Goes here..
    },
}

# Sample invalid JSON
invalid_json = {
    # Your Invalidate JSON Goes here..
    },
}

# Validate JSON against the schema
try:
    validate(instance=valid_json, schema=schema)
    print("Valid JSON")
except jsonschema.exceptions.ValidationError as e:
    print("Invalid JSON:", e)

try:
    validate(instance=invalid_json, schema=schema)
    print("Valid JSON")
except jsonschema.exceptions.ValidationError as e:
    print("Invalid JSON:", e)

You can customize JSON schema according to your specific requirements.