Flask JSONvalidator

Flask_jsonvalidator is a little library for validating request JSON data or pratically any json data, such as those obtained from external services or command-line parsing or even JSON data from a request to your api. All errors would be returned in JSON format too.

Installing

Install and update using pip :

$ pip install flask-jsonvalidator

Example

Here is a quick example to using flask_jsonvalidator, validating a request JSON data:

All neccessary imports

# validators.py

from flask_jsonvalidator import (
    JSONValidator,
    IntValidator,
    StringValidator,
    ArrayOfValidator
)

A simple validator class

# validators.py

class JSONCheck(JSONValidator):
    validators = {
        "name"    : StringValidator(max=15, min=2, nullable=False),
        "age"     : IntValidator(min=13, nullable=False),
        "hobbies" : ArrayOfValidator(validator=StringValidator(min=2,max=15, nullable=False))
    }

A simple decorator for the JSON data check

from functools import wraps
from flask import request, abort, jsonify

def response_data(data, error_code=None, description="", error_data=None, status_code=200):
    data = data
    has_error   = True if error_code else False

    if not description:
            # ERRORS_DESCRIPTION is a Dictionary containing error-codes as keys and their
            # description as the value

        description = ERRORS_DESCRIPTION.get(error_code,"")

    if has_error and error_code:
            # ERRORS_STATUS_CODE is a Dictionary containing error-codes as keys and their
            # corresponding status code as the value

        status_code = ERRORS_STATUS_CODE.get(error_code, BAD_REQUEST)

    ret_json = {
        "data" : data,
        "error_code"  : error_code,
        "has_error"   : has_error,
        "description" : description,
        "error_data"  : error_data,
        "status_code" : status_code
    }

    return jsonify(ret_json), status_code

def args_check(validator):
    def decorator(f):
        @wraps(f)
        def decorated_function(*args, **kwargs):
            json_data = request.json if request.json else {}
            no_err, msg = validator.validate(json_data)

            if not no_err:
                # E002 = Invalid Request JSON
                res = response_data(
                    data=None,
                    error_code=E002,
                    error_data=msg
                )

                return res

            return f(*args, **kwargs)
        return decorated_function
    return decorator

Use case

from flask import (
    Flask,
    jsonify,
    request,
    abort
)
from validators import JSONCheck

app = Flask(__name__)

users = []

@app.route("/users", methods=["GET"])
def get_users():
    return jsonify(users)

@app.route("/users", methods=["POST"])
@args_check(JSONCheck())
def add_user():
    global users

    user = dict(
        name   = request.json.get("name"),
        age    = request.json.get("age"),
        hobbies= request.json.get("hobbies")
    )
    users.append(user)
    return jsonify(user)

if __name__ == "__main__":
    app.run(debug=True)

keosariel/flask_jsonvalidator

Flask JSONvalidator

Installing

Example

A simple decorator for the JSON data check

Use case