meteor File Uploading Server/Client
Example
Uploading files can be easy or really complicated, depending on what you're wanting to do. In general, transfering a file itself isn't all that difficult. But there are lots of edge cases around attachments, binary files, and the like. And the real sticking point is horizontal scaling, and creating a solution that works when the server is cloned a second, third, and nth time.
Let's start with a basic server/client upload model. We begin by adding a file input element to the document object model.
<template name="example"> <input type=file /> </template>
Then attach an event to the input element within your controller, and call a local Meteor method ``startFileTransfer'' to initiate the transfer.
// client/example.js
Template.example.events({
'change input': function(ev) {
_.each(ev.srcElement.files, function(file) {
Meteor.startFileTransfer(file, file.name);
});
}
});
// client/save.js
/**
* @blob (https://developer.mozilla.org/en-US/docs/DOM/Blob)
* @name the file's name
* @type the file's type: binary, text (https://developer.mozilla.org/en-US/docs/DOM/FileReader#Methods)
*
* TODO Support other encodings: https://developer.mozilla.org/en-US/docs/DOM/FileReader#Methods
* ArrayBuffer / DataURL (base64)
*/
Meteor.startFileTransfer = function(blob, name, path, type, callback) {
var fileReader = new FileReader(),
method, encoding = 'binary', type = type || 'binary';
switch (type) {
case 'text':
// TODO Is this needed? If we're uploading content from file, yes, but if it's from an input/textarea I think not...
method = 'readAsText';
encoding = 'utf8';
break;
case 'binary':
method = 'readAsBinaryString';
encoding = 'binary';
break;
default:
method = 'readAsBinaryString';
encoding = 'binary';
break;
}
fileReader.onload = function(file) {
Meteor.call('saveFileToDisk', file.srcElement.result, name, path, encoding, callback);
}
fileReader[method](blob);
}
The client will then call the saveFileToDisk server method, which does the actual transfer and puts everything to disk.
//
/**
* TODO support other encodings:
* http://stackoverflow.com/questions/7329128/how-to-write-binary-data-to-a-file-using-node-js
*/
Meteor.methods({
saveFileToDisk: function(blob, name, path, encoding) {
var path = cleanPath(path), fs = __meteor_bootstrap__.require('fs'),
name = cleanName(name || 'file'), encoding = encoding || 'binary',
chroot = Meteor.chroot || 'public';
// Clean up the path. Remove any initial and final '/' -we prefix them-,
// any sort of attempt to go to the parent directory '..' and any empty directories in
// between '/////' - which may happen after removing '..'
path = chroot + (path ? '/' + path + '/' : '/');
// TODO Add file existance checks, etc...
fs.writeFile(path + name, blob, encoding, function(err) {
if (err) {
throw (new Meteor.Error(500, 'Failed to save file.', err));
} else {
console.log('The file ' + name + ' (' + encoding + ') was saved to ' + path);
}
});
function cleanPath(str) {
if (str) {
return str.replace(/\.\./g,'').replace(/\/+/g,'').
replace(/^\/+/,'').replace(/\/+$/,'');
}
}
function cleanName(str) {
return str.replace(/\.\./g,'').replace(/\//g,'');
}
}
});
That's sort of the bare-bones approach, and it leaves a lot to be desired. It's maybe good for uploading a CSV file or something, but that's about it.
