Flask JSON Schema Validator

Validate Flask JSON request data with schema files and route decorators.

Author

Daniel 'Vector' Kerr ([email protected])

License

Refer to LICENSE.txt.

Installation

pip install flask-jsonschema-validator

Sample Usage

Python Code

main.py

from flask import Flask, request, jsonify
from flask_jsonschema_validator import JSONSchemaValidator

app = Flask()
JSONSchemaValidator( app = app, root = "schemas" )

# Define a normal flask route, and then apply the `validate` decorator.
# Look for the `users.json` file, and use the `register` key as the schema source.
@app.route( '/register', methods = [ 'POST' ] )
@app.validate( 'users', 'register' )
def routeRegister():
  user = request.json
  return jsonify( user )

if __name__ == '__main__':
  app.run( port = 8080 )

Schema File

schemas/users.json

{
  "register": {
    "type": "object",
    "properties": {
      "name": { "type": "string", "minLength": 2, "maxLength": 100 },
      "email": { "type": "string", "format": "email" },
      "password": { "type": "string", "minLength": 8, "maxLength": 32 }
    },
    "required": [ "name", "email", "password" ]
  }
}

Run Server

python main.py

POST Data to Server

POST /register HTTP/1.0
Content-Type: application/json
Content-Length: 76

{
	"name": "fred",
	"email": "[email protected]",
	"password": "frediscool"
}

Handling Validation Errors

If the data validates correctly then the server will respond with the POST data as a JSON object.

If the data fails to validate, a jsonschema.ValidationError exception will be raised.

To handle the exception, you could register a Flask errorhandler. For example:

import jsonschema
from flask import Response

@app.errorhandler( jsonschema.ValidationError )
def onValidationError( e ):
  return Response( "There was a validation error: " + str( e ), 400 )