validate-all-types

validate-all-types

What is validate-all-types?

This package is a type validator mainly for Typescript (also works with Javascript). Ever faced those issues where you're trying to make sure a type any is an instance of an interface? This is the issue this package was designed to solve. With this package, you can safely assert the type for an object and return customised errors if the types are incorrect

Installation & Usage

$ npm install validate-all-types

or

$ yarn add validate-all-types

then import the module like this:

// Typescript
import { validate } from "validate-all-types"

// Javascript
const { validate } = require("validate-all-types")

Typescript typings are automatically included so there's no need to install anything like @types/validate-all-types !

How the validate function works

The validate object we imported earlier is a function which can take 2 (3: optional) parameters.

validate parameters:

Number	Type	Description
1	any	The object we are checking
2	Validator	A specific pattern to compare the object to (more about this later)
3	string?	The name of the root object when logs display errors. Defaults to * as root

The type Validator is something you don't need to worry about. Just know that it is the Typescript type for a pattern. Patterns can look like STRING() or NUMBER().

validate returns an object containing:

Property	Type	Description
success	boolean	Whether the validation of the object was a success or failure. true if success, false if failure
errors	string[]	The list of corrections to make if any

Making a pattern

There are infinite combinations of patterns we can make. The complexity of the pattern only depends on how much code you are willing to write.

Validation basics with a string

Here is how to validate a string

console.log(validate("string", STRING()))
// > { success: true, errors: [] }

console.log(validate(0, STRING()))
// > { success: false, errors: [ '*: Expected (*) to be of type `string`' ] }

Notice that in the error message, the root element is called * because as mentioned earlier, if we don't pass a third parameter into the validate() function, it names the root * by default.

The function STRING with nothing in the parameters represents a type string. This method can also take in items in the parameters:

Type	Description
(empty)	validates if the input is a string
RegExp	validates if the input is a string and matches the RegExp
...string[]	validates if the input is a string and matches any of the given strings

import { validate, STRING } from "validate-all-types"

console.log(validate("string", STRING()))
// > { success: true, errors: [] }
// This returned true because "string" is a string

console.log(validate(0, STRING()))
// > { success: false, errors: [ '*: Expected (*) to be of type `string`' ] }
// This returned false because 0 is not a string

console.log(validate("string", STRING(/^string$/)))
// > { success: true, errors: [] }
// This returned true because "string" matches the RegExp /^string$/

console.log(validate("string", STRING(/^something-else$/)))
// > { success: false, errors: [ '*: Expected (*) to match RegExp (/^something-else$/)' ] }
// This returned false because "string" didn't match the RegExp /^something-else$/

console.log(validate("string", STRING("does", "the", "string", "match", "?")))
// > { success: true, errors: [] }
// This returned true because "string" was passed into STRING() as a parameter

console.log(validate("string", STRING("doesn't", "match"), "my-string"))
// > { success: false, errors: [ `my-string: Expected (my-string) to be in (["doesn't","match"])` ] }
// This returns false because "string" wasn't passed into STRING() as a parameter
// Since I passed a third parameter to the validate function, the root got renamed

Validating a number with NUMBER()

Because STRING() validates strings, it's obvious that NUMBER() validates numbers. NUMBER() works the same was as STRING() except allows a different set of parameters:

Type	Description
(empty)	validates if the input is a number
...number[]	validates if the input is a number and matches any of the given numbers

import { validate, NUMBER } from "validate-all-types"

console.log(validate(3, NUMBER()))
// > { success: true, errors: [] }

console.log(validate("string", NUMBER()))
// > { success: false, errors: [ '*: Expected (*) to be of type `number`' ] }

console.log(validate(3, NUMBER(1, 2, 3, 4, 5)))
// > { success: true, errors: [] }

console.log(validate(3, NUMBER(6, 7, 8, 9, 10)))
// > { success: false, errors: [ '*: Expected (*) to be in ([6,7,8,9,10])' ] }

Validating a boolean with BOOLEAN()

BOOLEAN() allows comparison of booleans only

Type	Description
(empty)	validates if the input is a boolean
boolean	validates if the input is a boolean and if the booleans are equal

import { validate, BOOLEAN } from "validate-all-types"

console.log(validate(true, BOOLEAN()))
// > { success: true, errors: [] }

console.log(validate("string", BOOLEAN()))
// > { success: false, errors: [ '*: Expected (*) to be of type `boolean`' ] }

console.log(validate(true, BOOLEAN(true)))
// > { success: true, errors: [] }

console.log(validate(false, BOOLEAN(true)))
// > { success: false, errors: [ '*: Expected (*) to be `true`' ] }

Validating null with NULL()

NULL() doesn't allow variations of the parameters

Type	Description
(empty)	validates if the input is a null

import { validate, NULL } from "validate-all-types"

console.log(validate(null, NULL()))
// > { success: true, errors: [] }

console.log(validate(undefined, NULL()))
// > { success: false, errors: [ '*: Expected (*) to be of type `null`' ] }

Validating undefined with UNDEFINED()

Just like NULL(), UNDEFINED() doesn't allow variations of the parameters

Type	Description
(empty)	validates if the input is a undefined

import { validate, UNDEFINED } from "validate-all-types"

console.log(validate(undefined, UNDEFINED()))
// > { success: true, errors: [] }

console.log(validate(null, UNDEFINED()))
// > { success: false, errors: [ '*: Expected (*) to be of type `undefined`' ] }

Validating a list with LIST()

This one's a bit more complicated. LIST() allows a few sets of parameters:

Type	Description
(empty)	validates if the input is a list
...Validator[]	validates if the input is a list and checks if all items in the list match at least 1 of the Patterns stated

import { validate, LIST, STRING, NUMBER } from "validate-all-types"

console.log(validate([1, 2, 3, 4, 5], LIST()))
// > { success: true, errors: [] }

console.log(validate({ property: "value" }, LIST()))
// > { success: false, errors: [ '*: Expected (*) to be of type `array`' ] }

console.log(validate(["one", "two", "three"], LIST(STRING())))
// > { success: true, errors: [] }

console.log(validate([1, "two", 3], LIST(NUMBER())))
// > { success: false, errors: [ '* > [1]: Expected [1] to be of pattern defined' ] }

console.log(validate([1, "two", []], LIST(STRING(), NUMBER(), LIST())))
// > { success: true, errors: [] }
// And yes we also can verify LIST() within LIST()

console.log(validate([1, "two", null], LIST(STRING(), NUMBER())))
// > { success: false, errors: [ '* > [2]: Expected [2] to be of pattern defined' ] }

const usernames = ["jack", "_jack", "-jack"]
console.log(validate(usernames, LIST(STRING(/^[a-zA-Z]/)))) 
// > {
// >     success: false,
// >     errors: [
// >         '* > [1]: Expected [1] to be of pattern defined',
// >         '* > [2]: Expected [2] to be of pattern defined'
// >     ]
// > }
// Not every username matched /^[a-zA-Z]/

const codes = [34, 76, 92]
console.log(validate(codes, LIST(NUMBER(34, 76, 92))))
// > { success: true, errors: [] }
// Every code matched items in [34, 76, 92]

This way, we can make checking of list types much more detailed

Validating an object with OBJECT()

We can use OBJECT() to validate objects. OBJECT() only allows 1 optional parameter which maps out what the inner properties will look like

import { validate, OBJECT } from "validate-all-types"

console.log(validate({ property: "value" }, OBJECT()))
// > { success: true, errors: [] }
// Since { property: "value" } is an object, validate() returned true

console.log(validate({ property: "value" }, OBJECT({})))
// > {
// >     success: false,
// >     errors: [ '* > name: No type definitions for (property)' ]
// > }
// The pattern of {} means the object must have no properties

console.log(validate(
	{ property: "value" },
	OBJECT({ property: STRING() }
)))
// > { success: true, errors: [] }
// We set the OBJECT's params to an object with a property "property" and a value "value"
// Since "value" matches STRING(), validate() returned true

console.log(validate({
		property: "value"
	}, OBJECT({
		prop: STRING()
	})
))
// > {
// >     success: false,
// >     errors: [
// >         '*: Expected (*) to contain property (prop)',
// >         '* > property: No type definitions for (property)'
// >     ]
// > }
// Since there is no property for the type validation "prop", we got an error
// Since there is no type validation for the property "property", we got an error

console.log(validate(
	{
		property: "value",
		layer: {
			deepProperty: ["", 0, null, undefined, false]
		}
	},
	OBJECT({
		property: STRING(),
		layer: OBJECT({
			deepProperty: LIST(STRING(), NUMBER(0), NULL(), UNDEFINED(), BOOLEAN(false))
		})
	})
))
// > { success: true, errors: [] }
// We can even nest OBJECT() in OBJECT()

Validating the or operation with OR()

If you want either of a few patterns to match, use the OR() operator. This function takes multiple parameters:

Type	Description
...Validator[]	A list of patterns to test on the input

import { validate, OR, STRING, NUMBER, BOOLEAN } from "validate-all-types"

console.log(validate("string", OR()))
// > Error: *: Expected developer to provide at least 1 pattern for the OR operation
// An OR operation only works with at least one input

console.log(validate(
	"string",
	OR(STRING(), NUMBER())
))
// > { success: true, errors: [] }

console.log(validate(
	"string",
	OR(BOOLEAN(), NUMBER())
))
// > {
// >     success: false,
// >     errors: [ '*: Expected (*) to match at least one of the given patterns' ]
// > }

Using validate_express with Express.js

You can also import the module as a middleware to be used with express. This way, you can verify the types of the req.body or req.params before invalid types mess your code up

import { validate_express, OBJECT, STRING } from "validate-all-types"

// ----snip----

app.post("/body",
	validate_express("body", OBJECT({ usnm: STRING(), pswd: STRING() })),
	(req, res) => {
		const { usnm, pswd } = req.body as { usnm: string, pswd: string }
		console.log(`Username: ${usnm}`, `Password: ${pswd}`)
		res.end()
	}
)

// ----snip----

The validate_express takes in 2 parameters:

Number	Type	Description
1	"body" | "pattern"	Can either verify the req.body or req.params object
2	Validator	Pattern to compare the object with

Because of the middleware, in Typescript you can now safely use type assertions. Also, now for both Typescript and Javascript, you can safely use the variables like they are the defined types and not have to worry about invalid types crashing your server!