I'm trying to create a module that connects to my Database (couchDB using Cradle). In the end, the module exports the 'db' variable.
Here is the code:
var cradle = require('cradle'),
config = require('./config.js');
var db = new(cradle.Connection)(config.couchURL, config.couchPort, {
auth: {
username: config.couchUsername,
password: config.couchPassword
},
cache: true,
retries: 3,
retryTimeout: 30 * 1000
}).database('goblin'); //database name
//Check if DB exists
db.exists(function (err, exists) {
if (err && exists) {
console.log("There has been an error finding your CouchDB. Please make sure you have it installed and properly pointed to in '/lib/config.js'.");
console.log(err);
process.exit();
} else if (!exists) {
db.create();
console.log("Welcome! New database created.");
} else {
console.log("Talking to CouchDB at " + config.couchURL + " on port " + config.couchPort);
}
});
module.exports = db;
The problem is that the db.exists call is async, and if it doesn't exist I think the variable exports the variable before it's done, effecting the rest of the system.
It's being included in the executed node page the normal way:
var db = require('./couchdb.js');
Is there a way to prevent this from happening, or any best practices to tackle a problem like this without having a giant nested callback?
For reference, you can see the entire application right here ( https://github.com/maned/goblin ) , and the bug referenced for the project here ( https://github.com/maned/goblin/issues/36 ).
Embrace the async style. Instead of exporting db
from the module, export an async function like this:
module.exports = {
getDb: function(callback) {
db.exists(function(err, exists) {
if (exists && !err) {callback(db);} else { /* complain */ }
});
}
};
Now the application can just require('mymodule').getDb(appReady)
where appReady
accepts a db
object that is known to be valid and usable.
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