Detecting the end of a writeStream in Node

问题:

This is what I've got, and I keep getting an error because the file doesn't exist yet when I just do it sequentially.

How can I trigger an action upon the writeStream getting closed?

var fs = require('fs'), http = require('http');
http.createServer(function(req){
    req.pipe(fs.createWriteStream('file'));


    /* i need to read the file back, like this or something: 
        var fcontents = fs.readFileSync(file);
        doSomethinWith(fcontents);
    ... the problem is that the file hasn't been created yet.
    */

}).listen(1337, '127.0.0.1');

回答1:

Writable streams have a finish event that is emitted when the data is flushed.

Try the following;

var fs = require('fs'), http = require('http');

http.createServer(function(req, res){
    var f = fs.createWriteStream('file');

    f.on('finish', function() {
        // do stuff
        res.writeHead(200);
        res.end('done');
    });

    req.pipe(f);
}).listen(1337, '127.0.0.1');

Though I wouldnt re-read the file. You can use through to create a stream processor.