preconditions

@wroud/preconditions

@wroud/preconditions is a flexible and extensible library for managing preconditions in JavaScript and TypeScript applications. It simplifies the process of validating and preparing entities (e.g., nodes, connections, features) by providing a robust framework for defining and applying preconditions.

Features

• Entity-Specific Managers: Manage preconditions independently for different types of entities.
• Dynamic Applicability: Apply preconditions selectively to specific instances based on their data.
• Extensibility: Add new preconditions dynamically in a plugin-style manner.
• Check-Only and Fulfill Modes: Support both validating preconditions and attempting to fulfill them.
• TypeScript Support: Provides strong typing for enhanced developer experience.
• Pure ESM package

Installation

Install via npm:

npm install @wroud/preconditions

Install via yarn:

yarn add @wroud/preconditions

Documentation

For detailed usage and API reference, visit the documentation site.

Example

Define Your Entities

export interface Node {
  id: string;
  data: {
    requiresDatabaseConnection?: boolean;
  };
}

Define Preconditions

import type { IPrecondition } from "@wroud/preconditions";

export class DatabaseConnectionPrecondition implements IPrecondition<Node> {
  isApplicable(node: Node): boolean {
    return node.data.requiresDatabaseConnection === true;
  }

  async check(node: Node): Promise<boolean> {
    return databaseConnection.isEstablished();
  }

  async fulfill(node: Node): Promise<void> {
    await databaseConnection.connect();
  }
}

Set Up a Precondition Manager

import { PreconditionManager } from "@wroud/preconditions";
import { Node } from "./Node";
import { DatabaseConnectionPrecondition } from "./NodePreconditions";

const nodePreconditionManager = new PreconditionManager<Node>();
nodePreconditionManager.register(new DatabaseConnectionPrecondition());

Check and Fulfill Preconditions

const node: Node = { id: "node1", data: { requiresDatabaseConnection: true } };

const canLoad = await nodePreconditionManager.checkPreconditions(node);

if (canLoad) {
  console.log("Node can be loaded.");
} else {
  try {
    await nodePreconditionManager.fulfillPreconditions(node);
    console.log("Preconditions fulfilled. Node is ready to load.");
  } catch (error) {
    console.error("Failed to fulfill preconditions:", error);
  }
}

Changelog

All notable changes to this project will be documented in the CHANGELOG file.

License

This project is licensed under the MIT License. See the LICENSE file for details.