app-validation

app-validation

Part of app-helpers project.

Promise-based validation engine.

Installation

npm install app-validation

Usage

var createValidator = require('app-validation');

// Create user validation function
var validateUser = createValidator({
    email: ['required', 'email', 'only gmail'],
    password: ['required', 'longer than 5'],
    type: ['required', 'available user types']
});

// Sample user object

var user = {
    email: 'user@example.com',
    password: 'test',
    type: 'admin'
};

// Validate user object and return promise
validateUser(user)

    // If validation passes successfully, resolves promise with given data object
    .then(function (user) {

    })

    // If validation fails -> rejection with validation errors object
    .catch(function (errors) {
        // Fits well with app-controller
    });

Define custom rules

Rule is a simple function that takes 3 aprams: value to validate, field name of currently validating object property and context - whole validating data object.

v.extendRules({
    'valid name': function (value, field, context) {
        // ...
    }
});

var validate = v({
    name: ['valid name'],
    level: ['positive number']
});

validate({
    name: 'John',
    level: 10
});

// Will emit 'valid name' rule with params ('John', 'name', { name: 'John', level: 10 })

To emit failure rule function must return error message otherwise any falsy value or nothing.

var v = require('app-validation');

v.extendRules({
    'only gmail': function (value) {
        if (value.indexOf('@gmail') === -1) {
            return 'Not gmail actually';
        }
    }
});

// Rule could be async
v.extendRules({
    'user exists': function (email) {
        // Assume users.findByEmail returns promise
        return users.findByEmail(email).then(function (user) {
            if (!user) {
                return 'User does not exist';
            }
        });
    }
});

LICENSE

MIT