How to Upload and Download Files in Node.js (Express & Multer)

Here we will use multer middleware for uploading file. Click the link to know what is multer.

Setup The Project Folder
  • create a new folder using console/terminal.
  • open console/terminal type mkdir followed by the folder name you want to give.
  • change to that folder by typing cd folder name.




Setup Node For The Project
  • now type npm init on console/terminal.

  • the npm init will create a package.json file.But we can create it manually too.
  • just open the folder and add a new file and name it package.json and then we can structure it the same way as its been structured when using npm init.
  • the package.json will look like this.

  • now we will install packages for our project using npm install followed by package names we want to install.
  • the following packages will be installed express ejs body-parser multer mongoose.
  • this will generate a folder name node_modules which will contain all the node packages.
  • after the package installation  the package.json will look like this. 
  • now add a new file named it app.js.
  • now go back to package.json file and in scripts write start :app.js.
  • this will be the application entry point.
  • make new folders 1) views and 2) public.
  • in views add a file home.ejs.
  • here we using .ejs  extension for views file because the template engine we are using is ejs.
  • now in public folder make a new folder uploads.
  • the uploaded files will be stored in the uploads folder.


app.js
  1. mongoose.connect() - will setup the connection with local db on our system.
  2. localhost:27017/pics - pics is name of our database which will be created on server when we insert data in it.
  3. app.set("views",path.resolve(__dirname,"views")) - this tell express where views folder is.
  4. app.set("view engine","ejs") - this tells express that any file ending in .ejs should be rendered with ejs packages..
  5. express.static() - to serve static files such as images, CSS files, and JavaScript files, we using this middleware function.
  6. bodyParser - for fetching form data from the coming request.
  7. mongoose.Schema({}) - it contains the fields of our collection(table).
  8. mongoose.model() - it contains collection(table) name and the object containing collection(table) the field data.
  9. upload.single('pic') - in this we have to provide the same name of the name attribute which we used to upload the file.pic is the same name which is given in the name attribute . <input type="file"name="pic">. 
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  • home.ejs

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