irrelon-schema v1.0.4

Irrelon Schema

A (fairly) simple module to help validate JSON data against a schema. Useful for things like unit tests, checking responses from third-party APIs that are subject to change etc.

Install

npm i irrelon-schema

Usage

const Schema = require("irrelon-schema");

// Lets set up a schema where the "_id" field
// is a string that is required, and the "name"
// field is just a string. Notice that two different
// ways of describing a field are supported. Either
// directly giving a type or by providing a field
// definition object that defines "type" and
// potentially other options as well like "required". 
const userSchema = new Schema({
	"_id": {
		"type": String,
		"required": true
	},
	"name": String
});

// Now let's ask the schema to validate two different
// JSON objects:
const result1 = userSchema.validate({
	"_id": 1,
	"name": "Foo"
});

console.assert(result1.valid, true); // False, validation failed

// At this point, result1.valid === false because the
// field "_id" was given, but was a number not a string

// Now let's validate another data object:
const result2 = userSchema.validate({
	"_id": "1"
});

console.assert(result2.valid, true); // True, validation passed

Complex Schemas

Nested data, arrays, complex objects, sub-schemas.

Arrays

You can tell the schema what type of arrays you are expecting by using the shorthand or field definition methods.

Arrays that are given an element type will have every one of their elements checked during validation.

Array of Any

const arraySchema = new Schema({
	"_id": String,
	"arr": {
		"type": Array
	}
});

This is the same as above but shorthand:

const arraySchema = new Schema({
	"_id": String,
	"arr": Array
});

Array of Type

const arraySchema = new Schema({
	"_id": String,
	"arr": {
		"type": Array,
		"elementType": String
	}
});

This is the same as above but shorthand:

const arraySchema = new Schema({
	"_id": String,
	"arr": [String]
});

Shorthand typed array definitions do not check for types beyond the first element in the definition. This means that you can define a shorthand typed array like this:

const arraySchema = new Schema({
	"_id": String,
	"arr": [String, Number, Boolean]
});

BUT the "arr" field will ONLY be validated for strings. The definition does not allow for multiple types of elements in a single array in this version of Irrelon Schema.

Array of Other Schema

const subSchema = new Schema({
	"name": String
});

const arraySchema = new Schema({
	"_id": String,
	"arr": {
		"type": Array,
		"elementType": subSchema
	}
});

This is the same as above but shorthand:

const subSchema = new Schema({
	"name": String
});

const arraySchema = new Schema({
	"_id": String,
	"arr": [subSchema]
});

Sub-Schemas

You can define a field of any schema as needing to conform with another schema.

const userSchema = new Schema({
	"name": String,
	"age": Number
});

const arraySchema = new Schema({
	"_id": String,
	"user": {
		"type": userSchema
	}
});

This is the same as above but shorthand:

const userSchema = new Schema({
	"name": String,
	"age": Number
});

const arraySchema = new Schema({
	"_id": String,
	"user": userSchema
});