Node.js/Express - Render error when page not found

Question

I have the following controller/route definition in Node.js (using Express and Mongoose). What would be the leanest most appropriate way to handle Error when the user requests a page that does not exist?

  app.get('/page/:pagetitle', function(req, res) {       Page.findOne({ title: req.params.pagetitle}, function(error, page) {           res.render('pages/page_show.ejs',             { locals: {                 title: 'ClrTouch | ' + page.title,                 page:page             }           });       });   }); 

It currently breaks my app. I believe because I'm not doing anything with the error i'm just passing it to the view like a success?

TypeError: Cannot read property 'title' of null 

Thanks much.

Answer 1

Check out the express error-pages example. The principle is to register your app routes first, then you register a catch all 404 handler for all other requests that do not map to a route. Finally, a 500 handler is registered, as follows:

// "app.router" positions our routes  // specifically above the middleware // assigned below  app.use(app.router);  // Since this is the last non-error-handling // middleware use()d, we assume 404, as nothing else // responded.  app.use(function(req, res, next){   // the status option, or res.statusCode = 404   // are equivalent, however with the option we   // get the "status" local available as well   res.render('404', { status: 404, url: req.url }); });  // error-handling middleware, take the same form // as regular middleware, however they require an // arity of 4, aka the signature (err, req, res, next). // when connect has an error, it will invoke ONLY error-handling // middleware.  // If we were to next() here any remaining non-error-handling // middleware would then be executed, or if we next(err) to // continue passing the error, only error-handling middleware // would remain being executed, however here // we simply respond with an error page.   app.use(function(err, req, res, next){   // we may use properties of the error object   // here and next(err) appropriately, or if   // we possibly recovered from the error, simply next().   res.render('500', {       status: err.status || 500     , error: err   }); });