January 2012
Beginner
60 pages
1h 18m
English
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Storing Data in Files
Though you probably wouldn’t choose to store data in a text file over a database, there might be times when you want to write to and read from something highly portable—for example, if you were managing values in a config file. Writing to a file can’t give us the control over individual properties a data store can, of course, and it’s very slow, but there are still applications where a text file makes sense. Like writing to a database, writing to a file is done asynchronously, so if we want verification that it was done we’ll need to take any dependent actions from within a callback:
var connect = require("connect"),
fs = require("fs");
connect(
connect.static(__dirname + "/public"),
connect.bodyParser(),
function(req, res) {
var firstName = req.body.firstName,
lastName = req.body.lastName,
userName = firstName + " " + lastName,
stream;
if (firstName || lastName) {
// create a stream, and create the file if it doesn't exist
stream = fs.createWriteStream("user_name.txt");
} else {
return;
}
stream.on("open", function() {
// write to and close the stream at the same time
stream.end((firstName + "," + lastName + "\n"), "utf-8");
var html = "<!doctype html>" +
"<html><head><title>Hello " + userName + "</title></head>" +
"<body><h1>Hello, " + userName + "!</h1></body></html>";
res.end(html);
});
}
).listen(8000);Setting the data is easy, but it’s also fragile. We have to check that we’ve actually received data to avoid overwriting good data with bad, and if we had ...
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.