Firestore On Field Update

Firestore On Field Update is a lightweight utility package for Firebase Cloud Functions that simplifies handling updates to specific fields in a Firestore document.

Installation

You can install the package using npm:

npm install firestore-on-field-update

Usage

Importing the Package

To use the package, import the necessary functions and types:

import { onFieldUpdate, FieldUpdateHandlers } from 'firestore-on-field-update';
import * as functions from 'firebase-functions';
import * as admin from 'firebase-admin';

Defining Field Update Handlers

Field Update Handlers are functions that define the behavior to be executed when a specific field in a Firestore document is updated. You can define multiple handlers for different fields.

Here's an example of how to define Field Update Handlers:

const handlers: FieldUpdateHandlers<MyData> = {
  field1: (beforeValue, afterValue, change) => {
    // Handle the update for 'field1' here
  },
  field2: (beforeValue, afterValue, change) => {
    // Handle the update for 'field2' here
  },
};

The beforeValue parameter represents the previous value of the field, afterValue represents the new value, and change provides information about the Firestore document update.

Registering Field Update Handlers

To register the Field Update Handlers and start listening for updates, use the onFieldUpdate function provided by the package:

exports.myFunction = functions.firestore
  .document('myCollection/{docId}')
  .onUpdate((change) => {
    return onFieldUpdate(change, handlers);
  });

In the above example, myFunction is the Cloud Function that will be triggered when an update occurs in the specified Firestore document.

Example

Here's a complete example showcasing the usage of Firestore On Field Update:

import { onFieldUpdate, FieldUpdateHandlers } from 'firestore-on-field-update';
import * as functions from 'firebase-functions';
import * as admin from 'firebase-admin';

admin.initializeApp();

interface UserData {
  name?: string;
  email?: string;
  age?: number;
}

const handlers: FieldUpdateHandlers<UserData> = {
  name: (beforeValue, afterValue, change) => {
    console.log(`Name updated from '${beforeValue}' to '${afterValue}'`);
  },
  email: (beforeValue, afterValue, change) => {
    console.log(`Email updated from '${beforeValue}' to '${afterValue}'`);
  },
  age: (beforeValue, afterValue, change) => {
    console.log(`Age updated from '${beforeValue}' to '${afterValue}'`);
  },
};

exports.handleUserUpdate = functions.firestore
  .document('users/{userId}')
  .onUpdate((change) => {
    return onFieldUpdate(change, handlers);
  });

In the example above, whenever a document in the 'users' collection is updated, the corresponding Field Update Handlers will be triggered based on the updated fields.

License

This package is released under the ISC License.