Tiny Form Validation

A small utility class to handle validation of an object's properties using field rules.

Installation

yarn add git+https://github.com/cleverplatypus/tiny-form-validation.git

or

npm i git+https://github.com/cleverplatypus/tiny-form-validation.git

Usage

const model = {
    fields : {
        first_name : false,
        last_name : false,
        favourite_colour : false,
        email : false
        'address.postal_code' : false,
        uses_internet : false,
        ip_address : false
    },
    isValid : false
};

const fields = [
    {
        field : 'first_name'
    }, {
        field : 'last_name'
    }, {
        field : 'favourite_colour',
        isOptional : true
    }, {
        field : 'email',
        emptyFieldMessage : 'You need to enter your email address',
        tests : [
            {
                fn: (value, {field, data}) => isValidEmail(value), // isValidEmail is some fancy third party function
                message : `This doesn't look like an email address`
            }
        ]
    }, {
        field : 'address.postal_code',
        tests : [
            {
                fn : (value, {field, data, getCurrentCountryCode}) => isValidPostalCode(value, getCurrentCountryCode()), //other fancy external validation function
                message : `Please enter a valid postal code`
            }
        ]
    }, {
        field : 'ip_address',
        skipIf : ({data, field}) => !data.uses_internet,
        tests : [
            {
                fn : isIP4,
                stopOnSuccess: true
            }, {
                fn : isIP6,
                message : 'Please enter either an IP4 or IP6 address'
            }
        ]
    }, {
        fields : ''
    }
]
const context = {
    async getCurrentCountryCode() {
        return 'FR';
    }
}
const validation = new Validation(model, fields);

const formData = {
    first_name : 'Joe',
    last_name : 'Bro',
    address : {
        postal_code : '234324'
    },
    uses_internet : true,
    ip_address : '102.168.1.1'
}
validation.validate(formData, context);

model

The model parameter passed to the Validation constructor is the object that will contain validation results.

In its basic form it's only required to contain a fields property of type Object, however, when using reactive objects such as in VueJS, it's good practice to define all the model's properties as the UI might not be able to detect new properties.

The object will also contain a root boolean isValid field reflecting the overall validation outcome.

The value for each fields entry will be:

• false if the field wasn't validated
• true if the field passed validation
• a string with the validation failure description

NOTE: deep fields can be declared using dot notation.

The context object

An optional Object can be passed to the validate method to allow passing of additional data and/or functions to be used by the rule.tests.fn and rule.skipIf functions. The context object will be merged with {field : String, data : Object} before being passed to these functions.

API

Constructor

const validator = new Validation(model, fields);

validate(data, context)

The validate method accepts two parameters

• data: an Object with the data to validate
• context: an optional context Object

rule.tests[].fn(value, context)

Each test object must provide an async fn function that receives the current field's value to test plus the context object and returns a Boolean or a Promise<Boolean>. A true value signifies a passed test.

rule.tests[].stopOnSuccess, rule.tests[].stopOnFailure

Determines whether the workflow should stop after a test failure/success. The value, if specified, must be either:

• 'tests': will skip the following tests, if any
• 'fields': will stop evaluating the current rule

The library exports a STOP_OPTION object enumerating TESTS and FIELDS constants for this purpose.