Firebase Relationship

A promise based helper to manage relationships in your Firebase Realtime Database.

Usage

npm install firebase-relationship --save

import Firebase from 'firebase';
import Relationship from 'firebase-relationship';

// Create a new Firebase & Relationship instance
const firebase = Firebase.initializeApp({...});
const relationship = new Relationship('category_product');

// Create a new relationship between a category (id: 123) and a product (id: abc)
relationship.join(firebase, 123, 'abc');

// Remove the relationship
relationship.remove(firebase, 123, 'abc');

API

- constructor(name, path)

Creates and returns a new relationship.

• [name] Relationship name. Must include only one underscore.
• [path] Firebase path to store relationships. Defaults to 'relationship'. Must not contain leading or trailing forward slashes.

- join(instance, leftId, rightId, value?) : Promise

Creates a two way relationship between two IDs. The 4th param is an optional value to store with the relationship (defaults to true).

- remove(instance, leftId, rightId) : Promise

Removes a two way relationship between two IDs.

Magic Methods

When a new relationship instance is created, four magic methods are available for easy relationship querying. For example, with a "category_product" relationship:

// Get products for a category
relationship.getCategoryProducts(firebase, categoryId).then((snapshot) => {
  console.log('Products', snapshot.val());
});

// Get product categories
relationship.getProductCategories(firebase, productId).then((snapshot) => {
  console.log('Categories', snapshot.val());
});

// you can also get the internal refs for a join
const refA = relationship.getCategoryProductsRef;
const refB = relationship.getProductCategoriesRef;
// ... do a custom query ?

Each relationship name is pluralized.