I am currently testing how some code stands up against the following scenario:
- Node.js application is started and successfully establishes a connection to mongodb
- After it has successfully setup a connection, the mongodb server dies and all subsequent requests fail
To do this I have got the following code which makes use of the official driver (found here: https://github.com/mongodb/node-mongodb-native) :
MongoClient.connect('mongodb://localhost:27017/testdb', function(err, db) {
app.get('/test', function(req, res) {
db.collection('users', function (err, collection) {
console.log(err);
if (err) {
// ## POINT 1 ##
// Handle the error
}
else {
collection.find({ 'username': username }, { timeout: true }).toArray(function(err, items) {
console.log(err);
if (err) {
// ## POINT 2 ##
// Handle the error
}
else {
if (items.length > 0) {
// Do some stuff with the document that was found
}
else {
// Handle not finding the document
}
}
});
}
});
});
});
As the mongodb server is no longer running when the request is being handled, I'd made the assumption that at either the points which I have labelled ## POINT 1 ## or ## POINT 2 ##, it would return an error indicating a timeout; this however, isn't the case.
I have tried a number of different settings (including one you can see here that explicitly allows the cursor to timeout), however I cannot seem to enable it in any way. In every configuration I've tried Node.js will simply keep waiting for the find() operation to callback and it never does.
If I start the Node.js application before running mongodb, it catches the error in the connect callback fine, but if the connection dies after that it doesn't seem to handle it in any way.
Is there a setting I am missing or is there no way to detect connections being terminated after they've been established?
Edit: just to be clear, the username variable used in the find method is actually declared in my full code, the code I've put in this post is a cut down version to illustrate the structure and error checking.
