Sidewinder Validator

<div align='center'>

<h1>Sidewinder Validator</h1>

<p>Validation of Sidewinder Types</p>

[<img src="https://img.shields.io/npm/v/@sidewinder/validator?label=%40sidewinder%2Fvalidator">](https://www.npmjs.com/package/@sidewinder/validator)

</div>

## Overview

This package provides JSON schema validation for the `@sidewinder/type` package. It is built upon Ajv and provides additional validation support for `Uint8Array` as well as `void` used in Sidewinder Contracts.

License MIT

## Contents

- [Overview](#Overview)
- [Install](#Install)
- [Example](#Example)
- [Assert](#Assert)
- [Check](#Check)
- [Reference Types](#Reference-Types)

## Install

```bash
$ npm install @sidewinder/validation
```

## Example

The following shows general usual

```typescript
import { Validator } from '@sidewinder/validation'
import { Type } from '@sidewinder/type'

const T = Type.Object({
  a: Type.String(),
  b: Type.Number(),
  c: Type.Boolean(),
  d: Type.Uint8Array(),
  e: Type.Void(),
})

const validator = new Validator(T)

validator.assert({
  a: 'foo',
  b: 1,
  c: true,
  d: new Uint8Array(),
  e: null,
})
```

## Assert

The assert function will check the given data and throws with a `ValidatorError` if the data fails to check.

```typescript
import { Validator, ValidatorError } from '@sidewinder/validation'

const validator = new Validator(T)

try {
  validator.assert({
    a: 'foo',
    b: 1,
    c: true,
    d: new Uint8Array(),
    e: null,
  })
} catch (error) {
  if (error instanceof ValidatorError) {
    console.log(error.errors)
    console.log(error.message)
  }
}
```

## Check

The check function will check the given data and return a `ValidatorResult` object containing the result of the validation. This can be used
to test the value without throwing.

```typescript
import { Validator, ValidatorResult } from '@sidewinder/validation'

const validator = new Validator(T)

const result: ValidationResult = validator.check({
  a: 'foo',
  b: 1,
  c: true,
  d: new Uint8Array(),
  e: null,
})

if (!result.success) {
  console.log(result.errors)
  console.log(result.message)
}
```

<a name="Reference-Types"></a>

## Referenced Types

Sidewinder Validation supports schema referencing by appending the internal AJV schema compiler with additional schemas. Internally it maintains a singleton validation context that can be appended with additional schemas which allow the compiler to reference in downstream types. Because the compiler is singleton, each schema MUST have a unique `$id` across the entire application.

```typescript
import { Compiler, Validator } from '@sidewinder/validation'

// -------------------------------------------------------------------
// Referenceable Schema
// -------------------------------------------------------------------

const T = Type.Object(
  {
    a: Type.String(),
    b: Type.Number(),
    c: Type.Boolean(),
    d: Type.Uint8Array(),
    e: Type.Void(),
  },
  { $id: 'T' },
) // must be unique

Compiler.addSchema(T)

// -------------------------------------------------------------------
// Referenced Type
// -------------------------------------------------------------------

const R = Type.Ref(T)

const validator = new Validator(R)

// -------------------------------------------------------------------
// Check
// -------------------------------------------------------------------

const result = validator.check({
  a: 'foo',
  b: 1,
  c: true,
  d: new Uint8Array(),
  e: null,
})
```