check-compiler-js

A typescript-first schema rule compiler and validation library.

• no dependencies
• reusable schema definitions
• node.js and browsers
• tiny minified+gzipped

Install

Enable strict mode in tsconfig.json.

npm i check-compiler

Usage

Creating a simple string schema:

import {compile, Rule, Violation} from 'check-compiler';

// define
const id: Rule<string> = {
  type: 'string',
  min: 8,
  max: 8,
  pattern: /^[a-z]+$/,
  messages: {
    'string pattern': 'Required to be lowercase alpha only.',
  },
};

// compile
const checkId = compile(id);

// check
const input = 'abcdefgh';
const violations: Violation[] = [];
checkId(input, violations);

Creating an object schema:

import {compile, Rule, Violation} from 'check-compiler';

// type
type ResourceMap = {
  cpu?: number | null;
  memory?: number | null;
};

// define
const cpu: Rule<number | null> = {
  type: 'number',
  nullable: true,
  min: 0,
  max: 8000,
};
const memory: Rule<number | null> = {
  type: 'number',
  nullable: true,
  min: 0,
  max: 32768,
};
const resourceMap: Rule<ResourceMap | null> = {
  type: 'object',
  nullable: true,
  properties: {
    cpu,
    memory,
  },
};

// compile
const checkResourceMap = compile(resourceMap);

// check
const input: ResourceMap = {cpu: 1000, memory: 512};
const violations: Violation[] = [];
checkResourceMap(input, violations);

Defining validation by raising ValidationError:

import {compile, Check, Violation} from 'check-compiler';

export class ValidationError extends Error {
  constructor(readonly details: Violation[]) {
    super('There is one or more validation violations.');
  }
}

export function makeAssetValid<T>(check: Check<T>): (input: T) => void {
  return (input: T) => {
    const violations: Violation[] = [];
    check(input, violations);
    if (violations.length > 0) {
      throw new ValidationError(violations);
    }
  };
}

// compile
export const assertResourceMap = makeAssetValid(
  compile<ResourceMap>({
    type: 'object',
    nullable: true,
    properties: {
      cpu: {type: 'number', nullable: true, min: 0, max: 8000},
      memory: {type: 'number', nullable: true, min: 0, max: 32768},
    },
  }),
);

// assert
const input: ResourceMap = {cpu: 1000, memory: 512};
assertResourceMap(input);

Violation details example:

[
  {
    "location": "cpu",
    "message": "The value must fall within the range 0 - 8000.",
    "reason": "number range",
    "args": {
      "min": 0,
      "max": 8000
    }
  }
]