Firebase Functions Patterns

Directory Structure

functions/ ├── src/ │ ├── index.ts # Function exports │ ├── admin.ts # Firebase Admin SDK init │ ├── backfill/ # Data migration scripts │ ├── commentSuggestion/ # AI comment features │ ├── commentings/ # Comment activity tracking │ ├── notifications/ # Push notification functions │ ├── postings/ # Post activity tracking │ ├── replyings/ # Reply activity tracking │ └── shared/ # Shared utilities

Function Structure

import { onDocumentCreated } from 'firebase-functions/v2/firestore'; import admin from '../admin'; import { Post } from '../types/Post';

export const createPosting = onDocumentCreated( 'boards/{boardId}/posts/{postId}', async (event) => { const postData = event.data?.data() as Post; const { boardId, postId } = event.params;

if (!postData) {
  console.error('No post data found.');
  return null;
}

try {
  await admin.firestore()
    .collection('users')
    .doc(postData.authorId)
    .collection('postings')
    .add(postingData);
  console.log(`Created posting for user ${postData.authorId}`);
} catch (error) {
  console.error('Error writing posting:', error);
}

return null;

} );

Error Handling

Don't throw - let function complete gracefully:

try { await admin.firestore().collection('...').add(data); console.log(Successfully created ${resourceType}); } catch (error) { console.error(Error creating ${resourceType}:, error); // Don't throw - function should complete }

return null;

Build & Test

cd functions && npm install # Install deps cd functions && npm run build # Compile TypeScript cd functions && npm test # Run Jest tests