Multer middleware setup in Express - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is Multer in Express?

Multer is a middleware for Express that helps handle file uploads from forms. It processes files sent through HTTP requests and saves them to the server or memory.

beginner

How do you set up Multer to store uploaded files in a folder named 'uploads'?

You create a Multer storage engine using multer.diskStorage() and set the destination to 'uploads'. Then, pass this storage to multer() to create the middleware.

beginner

What does the 'single' method in Multer do?

The 'single' method tells Multer to accept a single file with the given field name from the form. It adds the file info to req.file.

intermediate

How can you limit the file size of uploads using Multer?

You can set the 'limits' option in Multer configuration with a 'fileSize' property in bytes to restrict the maximum upload size.

intermediate

What is the purpose of the 'fileFilter' option in Multer?

The 'fileFilter' option lets you control which files are accepted by checking the file type or other properties before saving.

Which Multer method is used to handle a single file upload?

A single

B array

C fields

D none

The 'single' method handles one file upload with the specified field name.

How do you specify the folder where Multer saves uploaded files?

A Using the 'limits' option

B Using the 'fileFilter' option

C Using the 'destination' option in diskStorage

D Using the 'single' method

The 'destination' option inside diskStorage sets the folder path for saving files.

What property in Multer limits the maximum file size?

A storage

B fileFilter

C maxFiles

D fileSize in limits

The 'fileSize' property inside 'limits' sets the max allowed file size in bytes.

Where does Multer store information about the uploaded file when using 'single'?

A req.body

B req.file

C req.files

D req.upload

For single file uploads, Multer adds the file info to req.file.

What does the 'fileFilter' function receive as arguments?

A req, file, callback

B req, res, next

C file, callback

D req, res

'fileFilter' receives the request, the file object, and a callback to accept or reject the file.

Explain how to set up Multer middleware to accept a single file upload and save it to a specific folder.

Think about creating storage, then middleware, then using it in a route.

Describe how to control which files Multer accepts and how to limit file size.

Consider validation and size restrictions in Multer config.