Author: adnanafzal565

// include MongoDB
const mongodb = require("mongodb")

// get MongoDB client
const mongoClient = mongogb.MongoClient

// connect with MongoDB server
const client = await mongoClient.connect("mongodb://localhost:27017")

const db = client.db("mongodb_gridfs")

// create GridFS bucket instance
const bucket = new mongodb.GridFSBucket(db)

// create GridFS bucket instance named "myBucketName"
const bucket = new mongodb.GridFSBucket(db, {
  bucketName: "myBucketName"
})

// npm install fs
const fs = require("fs")

// npm install ejs
app.set("view engine", "ejs")

// npm install express-formidable
const expressFormidable = require("express-formidable")
app.use(expressFormidable())

app.post("/upload", function (request, result) {
  // get input name="file" from client side
  const file = request.files.file
  
  // set file path in MongoDB GriDFS
  // this will be saved as "filename" in "fs.files" collection
  const filePath = (new Date().getTime()) + "-" + file.name
  
  // read user uploaded file stream
  fs.createReadStream(file.path)
  
    // add GridFS bucket stream to the pipe
    // it will keep reading and saving file
    .pipe(
      bucket.openUploadStream(filePath, {
        // maximum size for each chunk (in bytes)
        chunkSizeBytes: 1048576, // 1048576 = 1 MB
        // metadata of the file
        metadata: {
          name: file.name, // file name
          size: file.size, // file size (in bytes)
          type: file.type // type of file
        }
      })
    )
    // this callback will be called when the file is done saving
    .on("finish", function () {
      result.send("File saved.")
    })
})

app.get("/", async function (request, result) {
  const files = await bucket.find({
    // filename: "name of file" // 
  })
    .sort({
      uploadDate: -1
    })
    .toArray()
  result.render("index", {
    files: files
  })
})

<% if (files) { %>
  <% files.forEach(function (file) { %>
    <p><%= file.filename %></p>
    <img src="image/<%= file.filename %>" style="width: 200px;" />
  <% }) %>
<% } %>

app.get("/image/:filename", async function (request, result) {
  // get file name from URL
  const filename = request.params.filename
  
  // get file from GridFS bucket
  const files = await bucket.find({
    filename: filename
  })
  .toArray()
  
  // return error if file not found
  if (!files || files.length == 0) {
    return result.status(404).json({
      error: "File does not exists."
    })
  }
  
  // it will fetch the file from bucket and add it to pipe
  // result response is added in the pipe so it will keep
  // returning data to the client
  bucket.openDownloadStreamByName(filename)
    .pipe(result)
})

// 
const ObjectId = mongodb.ObjectId

app.post("/files/del", async function (request, result) {
  // get ID from data
  const _id = request.fields._id
  
  // delete file from bucket
  await bucket.delete(ObjectId(_id))
  
  // return response
  result.send("File has been deleted.")
})