Express - Backend Recipes

Installation

Install the Filejar client and required dependencies:

npm install filejar express multer

Setup

Create Filejar Client

Initialize the Filejar client in your Express application:

import express from 'express';
import Filejar from 'filejar';

const app = express();

// Initialize Filejar client
const filejar = new Filejar({
  apiKey: process.env.FILEJAR_API_KEY,
});

Single File Upload Endpoint

Create an endpoint to upload a single file:

import multer from 'multer';
import { fileRepo } from '@/lib/db-repo';

// Configure Multer for file uploads
const storage = multer.memoryStorage();
const upload = multer({ 
  storage: storage,
  limits: { fileSize: 10 * 1024 * 1024 } // 10MB limit
});

// Single file upload endpoint
app.post('/api/files/upload', upload.single('file'), async (req, res) => {
  try {
    if (!req.file) {
      return res.status(400).json({ error: 'No file uploaded' });
    }

    // Convert buffer to File-like object for uploadFile
    const file = new File([req.file.buffer], req.file.originalname, {
      type: req.file.mimetype,
    });

    // Upload file to Filejar
    // The body parameter is optional - Filejar will automatically use the file's original name
    const result = await filejar.upload.uploadFile([file]);
    // Or with explicit file name:
    // const result = await filejar.upload.uploadFile([file], {
    //   body: [{ file_name: req.file.originalname }],
    // });

    if (!result.response || result.response.length === 0) {
      return res.status(500).json({ error: 'Failed to upload file' });
    }

    const uploadResult = result.response[0];
    const acknowledged = result.acknowledge[0];
    
    // Check if acknowledgment was successful
    if ('error' in acknowledged) {
      return res.status(500).json({ error: acknowledged.error });
    }

    // Construct file URL using the key
    const fileUrl = `https://cdn.filejar.dev/${uploadResult.key}`;
    
    // Store file metadata in database
    const savedFile = await fileRepo.create({
      key: uploadResult.key,
      uploadId: uploadResult.upload_id,
      originalName: req.file.originalname,
      contentType: acknowledged.content_type,
      size: acknowledged.size,
      url: fileUrl,
      uploadedBy: req.authId, // Assuming you have auth middleware
    });

    res.json({
      success: true,
      file: savedFile,
    });
  } catch (error) {
    console.error('Upload error:', error);
    if (error instanceof Filejar.APIError) {
      return res.status(error.status || 500).json({ 
        error: error.message,
        status: error.status 
      });
    }
    res.status(500).json({ error: 'Failed to upload file' });
  }
});

Multiple Files Upload Endpoint

Create an endpoint to upload multiple files:

// Multiple files upload endpoint
app.post('/api/files/upload-multiple', upload.array('files', 10), async (req, res) => {
  try {
    if (!req.files || req.files.length === 0) {
      return res.status(400).json({ error: 'No files uploaded' });
    }

    // Convert buffers to File-like objects
    const files = req.files.map(file => 
      new File([file.buffer], file.originalname, { type: file.mimetype })
    );

    // Upload all files to Filejar
    // The body parameter is optional - Filejar will automatically use each file's original name
    const result = await filejar.upload.uploadFile(files);
    // Or with explicit file names:
    // const result = await filejar.upload.uploadFile(files, {
    //   body: req.files.map(file => ({ file_name: file.originalname })),
    // });

    if (!result.response || result.response.length === 0) {
      return res.status(500).json({ error: 'Failed to upload files' });
    }

    // Store file metadata in database
    const filePromises = result.response.map(async (uploadResult, index) => {
      const originalFile = req.files[index];
      const acknowledged = result.acknowledge[index];
      
      // Skip if acknowledgment failed
      if ('error' in acknowledged) {
        console.error(`Failed to acknowledge ${originalFile.originalname}:`, acknowledged.error);
        return null;
      }

      // Construct file URL using the key
      const fileUrl = `https://cdn.filejar.dev/${uploadResult.key}`;
      
      const savedFile = await fileRepo.create({
        key: uploadResult.key,
        uploadId: uploadResult.upload_id,
        originalName: originalFile.originalname,
        contentType: acknowledged.content_type,
        size: acknowledged.size,
        url: fileUrl,
        uploadedBy: req.authId,
      });

      return savedFile;
    });

    const uploadedFiles = (await Promise.all(filePromises)).filter(file => file !== null);

    res.json({
      success: true,
      files: uploadedFiles,
      count: uploadedFiles.length,
    });
  } catch (error) {
    console.error('Upload error:', error);
    if (error instanceof Filejar.APIError) {
      return res.status(error.status || 500).json({ 
        error: error.message,
        status: error.status 
      });
    }
    res.status(500).json({ error: 'Failed to upload files' });
  }
});

Retrieve Files from Database

Create an endpoint to retrieve file information using the stored key:

import { fileRepo } from '@/lib/db-repo';

// Get file by ID
app.get('/api/files/:id', async (req, res) => {
  try {
    const { id } = req.params;

    const file = await fileRepo.findById(id);

    if (!file) {
      return res.status(404).json({ error: 'File not found' });
    }

    res.json(file);
  } catch (error) {
    console.error('Error retrieving file:', error);
    res.status(500).json({ error: 'Failed to retrieve file' });
  }
});

// Get all files
app.get('/api/files', async (req, res) => {
  try {
    const files = await fileRepo.findAll();

    res.json({ files });
  } catch (error) {
    console.error('Error retrieving files:', error);
    res.status(500).json({ error: 'Failed to retrieve files' });
  }
});

Client-Side Usage

Upload Single File

// Client-side: Upload single file
async function uploadFile(file: File) {
  const formData = new FormData();
  formData.append('file', file);

  const response = await fetch(`${API_BASE_URL}/api/files/upload`, {
    method: 'POST',
    body: formData,
  });

  const data = await response.json();
  return data.file; // Contains id, filejarId, filejarKey, name, url
}

Upload Multiple Files

// Client-side: Upload multiple files
async function uploadFiles(files: File[]) {
  const formData = new FormData();
  files.forEach(file => {
    formData.append('files', file);
  });

  const response = await fetch(`${API_BASE_URL}/api/files/upload-multiple`, {
    method: 'POST',
    body: formData,
  });

  const data = await response.json();
  return data.files; // Array of file objects
}

Retrieve File

Simply use the file key to construct the URL:

// Direct URL access using the file key
const fileUrl = `https://cdn.filejar.dev/${key}`;

// Example: Display file in img tag
<img src={`https://cdn.filejar.dev/${fileKey}`} alt="Uploaded file" />

Complete Example

Here’s a complete Express server setup with all endpoints:

import express from 'express';
import multer from 'multer';
import Filejar from 'filejar';
import { fileRepo } from '@/lib/db-repo';

const app = express();
const port = process.env.PORT || 3000;

app.use(express.json());

// Initialize Filejar client
const filejar = new Filejar({
  apiKey: process.env.FILEJAR_API_KEY,
});

// Configure Multer
const upload = multer({ 
  storage: multer.memoryStorage(),
  limits: { fileSize: 10 * 1024 * 1024 } // 10MB
});

// Single file upload
app.post('/api/files/upload', upload.single('file'), async (req, res) => {
  // ... single upload code from above
});

// Multiple files upload
app.post('/api/files/upload-multiple', upload.array('files', 10), async (req, res) => {
  // ... multiple upload code from above
});

// Get file by ID
app.get('/api/files/:id', async (req, res) => {
  // ... get file code from above
});

// Get all files
app.get('/api/files', async (req, res) => {
  // ... get all files code from above
});

app.listen(port, () => {
  console.log(`Server running on http://localhost:${port}`);
});

Getting started

Backend Recipes

​Installation

​Setup

​Create Filejar Client

​Single File Upload Endpoint

​Multiple Files Upload Endpoint

​Retrieve Files from Database

​Client-Side Usage

​Upload Single File

​Upload Multiple Files

​Retrieve File

​Complete Example