errorhandling

errorhandling.js

//A third way.
//In a business logic module. Note: replace "internal" methods with your own logic (redis, mongodb, etc).
function getBlogByGuid(id, callback) {
    internalLoad(id, function(err, post) {
        if (err) return callback(err);
    });
}

function deleteDocumentById(id, callback) {
    internalDelete(id, function(err) {
        callback(err); //err will either be an error, or null/undefined.
    });
}

function handleDelete(id, callback) {
    getBlogByGuid(id, function(err, post) {
        if (err) return callback(err);
        deleteDocumentById(id, function(err) {
            callback(err); //again, err will be an error or null/undefined.
        });
    });
}

//Somewhere in your web code...
var business = require('./business'); //has the business logic
app.post('/my/delete/url/', function(req, res) {
    if (!('guid' in request.url.query)) {
        handleError(new Error('Missing guid'));
    }

    business.handleDelete(request.query.guid, function(err) {
        if (err) return handleError(err, res);
        res.send(200, 'Blog deleted');
    });
});

//Error handler will handle Error objects or strings--though it's recommended to pass in Errors only.
function handleError(error, res) {
    if (errorinstanceof Error) {
        res.send(500, error.message);
    }
    else if (typeof error== 'string' || error instanceof String) {
        res.send(500, error);       
    }
    else {
        throw new Error('Unrecognized type for error handler.');
    }
}