Flask Validator

This is a validation library for flask app or api

Installation

pip install flask-validator

Example (Usage)

from flask import Flask, jsonify
from flask_validator import ValidatorEngine

app = Flask(__name__)
validator = ValidatorEngine(app)

@app.route('/index', methods=['POST'])
@validator('json', {
    'name': ['required', 'maxa:10']
})
def index():
    return jsonify(
        status=True
    ),200


@app.route('/users/<name>', methods=['POST'])
@validator('query_string', {
    'name': ['required', 'max:10', 'min:3']
})
def test_exp(name):
    return jsonify(
        status=True
    ),200

This library uses function decorator pattern, which means the incomming request data is validated before the request hit the route function

On Error

When there is a validation error, library return a 422 http response status code and a json data containing the error messages.

    {
        status: false,
        errors: {
            name: ["This field is required"]
        }
    }

instantiating ValidatorEngine Class

validator = ValidatorEngine(app)

or when use using flask factory function pattern

    validator = ValidatorEngine()
    validator.init_app(app)

Using the validator object

Decorate your route function with the validator object like this.

    @validator(<where-to-check-for-data>, <validation-logic>)

so you have

    @validator('json', {
        'name': ['required', 'min:23']
    })

The first argument to the validator decorator is the place where you want the validator to check for incoming data "json ", "query_sting", "headers ".

The second arguement is a dictionary holding the validation rules

    { <Field to validate >: [<Rules: A list if the validtion rules to check on the field sepcified> ]}

Built-in Validation Rules

json

Using the json rule, the validator expects a JSON object from the client. It validates fields in JSON data.

query_string

The query_string rule validates the URL query arguments passed by the client.

headers

Validates the request headers

Built-in Validation Rules Args

You can specify extra argument to a rule like character limit for a parameter and required values.

required

Specify a required value.

You can require a value in a JSON payload as follows:

@validator('json', {
    'name': ['required', 'min:23']
})

max and min

The maximum and minimum character for a parameter

@validator('json', {
    'phone': ['required', 'min:8', 'max:16']
})

alpha

This check that the input under validation contains only alphabets (A-Za-z)

@validator('json', {
    'name': ['alpha']
})

alphanumeric

This check that the input under validation contains both alphabets and numbers (A-Za-z0-9)

@validator('json', {
    'username': ['alphanumeric']
})

list

This check that the input under validation is a list

@validator('json', {
    'choice': ['list']
})

You can also set your validation to make sure the list is of a specific length

@validator('json', {
    'choice': ['list:3']
})

this will check test the data for list and of length 3

bool

This check that the input under validation is a boolean datatype (True/False) or (1/0)

@validator('json', {
    'agreed': ['bool']
})

regex

The regex validator matches the whole string for the regular expression pattern

@validator('json', {
    'abc-123-XYZ': [r'regex:[\w\d\-]+']
})

date:<format>

This check that the input under validation is a date that matches the <format> provided.

 @validator('json', {
    'delivery_date': ['date:%Y/%m/%d %H:%M:%S']
 })

The format is the standard date format codes specified in the datetime library in python check it here (date formats codes)

date:<format>,<value>

You can also validate that the date matches the format and that date value sepecified

@validator('json', {
    'delivery_date': ['date:%Y/%m/%d %H:%M:%S,2017/03/04 01:02:45']
})

date_before:<format>,<value>

Checks that the date matches the format and is before the date value specified

@validator('json', {
    'delivery_date': ['date_before:%Y/%m/%d %H:%M:%S,2017/03/04 01:02:45']
})

date_before_or_equal:<format>,<value>

Checks that the date matches the format and is before or equals to the date value specified

@validator('json', {
    'delivery_date': ['date_before_or_equal:%Y/%m/%d %H:%M:%S,2017/03/04 01:02:45']
})

date_after:<format>,<value>

Checks that the date matches the format and is after the date value specified

@validator('json', {
    'delivery_date': ['date_after:%Y/%m/%d %H:%M:%S,2017/03/04 01:02:45']
})

date_after_or_equal:<format>,<value>

Checks that the date matches the format and is after or equals to the date value specified

@validator('json', {
    'delivery_date': ['date_after_or_equal:%Y/%m/%d %H:%M:%S,2017/03/04 01:02:45']
})

Contributions

...

Author

Created by Adewumi Ogunbiyi