Read file with node.js, mongoose, gridfs-stream

Question

I am using mongoose and gridfs-stream to store and read files from mongodb. I am following the example here: https://github.com/aheckmann/gridfs-stream

Writing files int

Answer 1

what is cover give an format to file than write or read

const express = require("express");
const routes = express.Router();
const mongoose = require('mongoose');
mongoose.connect("mongodb://localhost:27017/gridfs");
var conn = mongoose.connection;
var path = require("path");
var Grid = require("gridfs-stream");
var fs = require("fs");
Grid.mongo = mongoose.mongo;

var datapath = path.join(__dirname, "../public/1.jpg");

conn.once("open",() =>{
    console.log('connections is opened ');
    console.log(conn.db + "wahab this is running");
    var gfs = Grid(conn.db);
    var filestream = gfs.createWriteStream({
      filename: "wahab.jpg"
    });
    fs.createReadStream(datapath).pipe(filestream);
    filestream.on("close",(file) =>{
      console.log(file.filename  + " Write to DB");
    });

 });

 });

Answer 2

The example code on GitHub was a little bit misleading; I initially received the same error message you did. In my case, it was due to the fact that I was attempting to read the file before the write stream had finished. I resolved this by doing the read inside the event handler for "close":

var fs = require("fs"),
    mongo = require("mongodb"),
    Grid = require("gridfs-stream"),
    gridfs,
    writeStream,
    readStream,
    buffer = "";

mongo.MongoClient.connect("mongodb://localhost/gridfs_test", function (err, db) {
    "use strict";
    gridfs = Grid(db, mongo);

    // write file
    writeStream = gridfs.createWriteStream({ filename: "test.txt" });
    fs.createReadStream("test.txt").pipe(writeStream);

    // after the write is finished
    writeStream.on("close", function () {
        // read file, buffering data as we go
        readStream = gridfs.createReadStream({ filename: "test.txt" });

        readStream.on("data", function (chunk) {
            buffer += chunk;
        });

        // dump contents to console when complete
        readStream.on("end", function () {
            console.log("contents of file:\n\n", buffer);
        });
    });
});