Express-Middleware-Upload

Express middleware to assist with file upload CRUD (uploads, listing, reading and deletion).

var emu = require('express-middleware-upload');
var express = require('express');
var app = express();
 
app.use('/api/files/:path?', emu({
    path: '/my/storage/path',
}));

By default "EMU" will expose an unloader at the specified end-point as well as the ability to list, read and delete files. In the above example the following URL methods will upload, list, read and delete files:

Method	URL	Payload / Headers	Description
POST	/api/files	Multipart file(s)	Upload a file / files to the API end-point
GET	/api/files		List all uploads at the end-point
GET	/api/file/FILENAME		Read a specific filename at the end-point
DELETE	/api/file/FILENAME		Delete a specific filename at the end-point
MOVE	/api/file/FILENAME	headers.destination	Rename a file

API

The base usage of 'EMU' is to attach it to an Express end-point and give it a configuration object.

app.use('/api/files/:path?', emu(configOptions));

The following table lists the valid configuration options. The only mandatory setting is path, all other settings are optional.

Option	Type	Default	Description
path	String or Function		Mandatory path of where to store uploaded files. If this is a function it is called as func(req, res, next) and is expected to fire the callback as func(err, computedPath)
basePath	String		Prefix automatically prepended onto options.path (this is separate so it can be set globally to your application root via emu.defaults.basePath)
errorHandler	Function		How to output errors. This should be a function called as (req, res, statusCode, message)
escape	Boolean	true	Automatically escape all filenames so they are URL safe
postPath	String	'upload'	How to name the uploaded file. 'upload' = Use the uploaded filename appended to options.path, 'param' = Use the path specified in req.params.path (implies options.limit=1), 'dir' = Use the path as the directory to store the file in and the filename from the uploaded filename
field	String	'file'	What the multi-part field name is (if falsy, all fields will be accepted - this is not recommended)
expect	Number	0	The minimum number of files to expect, set to 0 for no minimum
limit	Number	0	The maximum number of files to accept, set to 0 for no maximum
list	Function, Array, String, Boolean		Middleware(s) to run before listing files at a given path. See below for comments.
get	Function, Array, String, Boolean		Middleware(s) to run before reading a specific file. See below for comments.
post	Function, Array, String, Boolean		Middleware(s) to run before accepting an file upload. See below for comments.
delete	Function, Array, String, Boolean	false	Middleware(s) to run before deleting a file. See below for comments.
move	Function, Array, String, Boolean	false	Middleware(s) to run before allowing a file to be renamed. See below for comments.
postProcess	Function, Array		Middleware(s) to run after accepting a file upload, this can override the output by calling res.send() manually. req.files will also have an storagePath property which will indicate where on disk the file was saved by EMU

Middleware

The list, get, post and delete options can all accept either a function, an array of functions, a string or a boolean.

• If the value is a function it is executed as a regular Express middleware (called as func(req, res, next)).
• If the value is an array the functions are executed in order specified (each called as func(req, res, next)).
• If the value is a string its functionality is determined by another option. E.g. setting list: 'post' property instructs EMU to use the same middleware specified in post.
• If the value is a boolean it is used to universally enable or reject the method. Setting the value to true will allow the method (the default anyway) and setting it to false will disable it entirely.

app.use('/api/files/:path?', emu({
    post: function(req, res, next) { // Only allow the 'post' method if the user is valid (this assumes something like Passport to provide the `req.user` object)
        if (!req.user) return res.sendStatus(403);
        next();
    },
    list: 'post', // Copy the same middleware from 'post'
    get: 'post', 
    delete: false, // Forbid all deletes
    move: false, // Forbid all renames
});

Troubleshooting

• The API uses req.params.path to match the file that operations should be performed on. This means you must have that in your file query. So this is right: app.use('/api/somewhere/:path', ...) but this wont work: app.use('/api/somewhere/:file', ...)