Trus

Scalable and flexible async validation solution

Installation

npm install --save trus

express extension available here

Usage

const validate = require("trus").validate;
const { condition } = require("trus").methods;

var validateEven = validate(
    condition( i => i&2 == 0 )
);

validateEven(4).then().catch()  // resolves

validateEven(5).then().catch() // rejects

trus.validate

validate is a function that gets a method and generates a validation function, using this method.

Validates are simple. For instance, the default validate function looks like:

var validate = method => context => method(context);

It returns a function that gets an input and returns a promise, wich will be resolved/rejected depending on supplied method's behavior.

const trus = require("trus");
var allowOnly5 = trus.validate( trus.methods.condition( i => i==5 ) );
only5( 5 )
    .then( () => onValidationSuccess() ) // <=
    .catch( e => onValidationFail(e) )

trus.methods

A trus method is a logic unit, formed as a function, that gets an input (from the validate function), and returns a Promise. The method decides weather to resolve or reject, depending on injected context.

For example, the any method that resolves for any input, looks like:

var any = context => Promise.resolve(true);

Sometimes methods are factories, that generates the methods itself, letting you pass values into it. For example, the allOf method lets you pass in as many sub-methods as you want, and will resolve since all of them did resolved.

validate( allOf( any, none ) )

Factories methods looks like:

var myMethod = (params...) => context => {...};

For example, a method that checks if the context is matching a value will look like:

var myMethod = allowedValue => async context => {
  if(context != allowedValue)
    throw new Error(context + " != " + allowedValue)
});

var only3 = validate( myMethod(3) )

only3( 2 )
    .then()
    .catch() // <-- will reject

Built-in methods

Name	Description	Usage
any	Allow any input	validate( any )
none	Block any input	validate( none )
allOf	pass if all of the above has passed	validate( allOf( any, any ) )
someOf	pass if at least one of the above has passed	validate( someOf( any, none ) )
condition	runs a condition function as a validation	validate( condition( context => context == 1 ) )
not	returns the opposite from inner method	validate( not( any ) )

Trus methods and validate functions are extremely extensible, feel free to extend them yourself.