Knight Misfit by Coderitter

A definition of a misfit as a result of a validation when a constraint is not met.

Install

npm install knight-misfit

Overview

A misfit contains the following information.

export class Misfit<ValuesType = any> {
  constraint!: string
  properties!: string[]
  values?: ValuesType
  message?: string
}

The constraint is an arbitrary name of a constraint that, when it was checked, did not fit. The properties is an array of property names of an object which values are constrained by the constraint. The values are an arbitrary object which hold the parameters that were used by the constraint but also other values like the ones that were found on the object. It is used to give contextual information on what went wrong during the constraint checking. The message can be shown to a user in an application.

The constraint and the properties are expected to be there, but the constructor does not enforce them. Find your own workflow of filling them and then only give the misfit out to a user if both of them are set!

The misfit references either one property or multiple properties. One property is more common, but there might also be constraints that involve multiple properties. There are several methods to find out and to work with both variants.

import { misfit } from 'knight-misfit'

let misfit = new Misfit

misfit.properties = [ 'property1', 'property2' ]
misfit.isMultipleProperties()

misfit.property = 'property'
misfit.isSingleProperty()

Constructor

There are two constructor variants. Both of them can take an arbitrary amount of the supported parameters, thus you can specify for example only the first one, leaving the others out.

import { misfit } from 'knight-misfit'

// The constructor variant to set every property
new Misfit('Required', 'property', { timeOfCheck: new Date }, 'The value must not be empty!')
new Misfit('Required', ['property1', 'property2'], { timeOfCheck: new Date }, 'The value must not be empty!')

// The constructor variant to set only the values object and the message
new Misfit({ timeOfCheck: new Date }, 'The value must not be empty!')

Prepending a prefix to all property names

When you are dealing with nested objects, you might want to add the property path to the property name, so that it is known, that the property is from a sub object.

import { Misfit } from 'knight-misfit'

let misfit = new Misfit
misfit.properties = ['p1', 'p2']
misfit.addPrefix('subObject.')

misfit.properties == ['subObject.p1', 'subObject.p2']