Dynamic routes with Express.js -- is this even possible?

Question

Every time I update the database with a new menu item, I'm trying to get the routing to update with one more route. Here's my sad little ugly attempt: Here in app.js, I check the menu database and shazaam...routes are made on the fly at startup. Cool!: ``` // in app.js // var attachDB = function(req, res, next) { req.contentdb = db.content; req.menudb = db.menu; req.app = app; // this is the express() app itself req.page = PageController; next(); }; db.menu.find({}, function (err, menuitems){ for(var i=0; record = menuitems[i]; i++) { var menuitem = record.menuitem; app.all('/' + menuitem, attachDB, function(req, res, next) { console.log('req from app all route: ',req) PageController.run(menuitem, req, res, next); }); } http.createServer(app).listen(config.port, function() { console.log( '
Express server listening on port ' + config.port ); }); }); ``` Not real elegant but it's a proof of concept. Now here's the problem: When I save a new menu item in my Admin.js file, the database g…

Accepted Answer

I would suggest two changes:

- Move this menu attachment thing to a separate module.

- While you're at it, do some caching.

Proof of concept menu db function, made async with setTimeout, you'll replace it with actuall db calls.

```
// menuitems is cached here in this module. You can make an initial load from db instead.
var menuitems = [];
// getting them is simple, always just get the current array. We'll use that.
var getMenuItems = function() {
    return menuitems;
}

// this executes when we have already inserted - calls the callback
var addMenuItemHandler = function(newItem, callback) {
    // validate that it's not empty or that it does not match any of the existing ones
    menuitems.push(newItem);
    // remember, push item to local array only after it's added to db without errors
    callback();
}
// this one accepts a request to add a new menuitem
var addMenuItem = function(req, res) {
    var newItem = req.query.newitem;

// it will do db insert, or setTimeout in my case
    setTimeout(function(newItem){
        // we also close our request in a callback
        addMenuItemHandler(newItem, function(){
            res.end('Added.');
        });

}, 2000);
};

module.exports = {
    addMenuItem: addMenuItem,
    getMenuItems: getMenuItems
}
```

So now you have a module menuhandler.js. Let's construct it and use it in our app.

```
var menuHandler = require('./menuhandler');
var app = express();
// config, insert middleware etc here

// first, capture your static routes - the ones before the dynamic ones.
app.get('/addmenuitem', menuHandler.addMenuItem);
app.get('/someotherstaticroute', function(req, res) {
    var menu = menuHandler.getMenuItems();
    res.render('someview', {menu: menu});
});

// now capture everything in your menus.
app.get('/:routename', function(req, res){
    // get current items and check if requested route is in there.

app.get('/', function(req, res) {
    // ...
});
```

Now you don't go to db if there were no new updates (since menuitems array is always up to date) so your initial view is rendered faster (for that 1 db call, anyway).

Edit: oh, I just now saw your Model.js. The problem there is that `this` refers to the object you have returned:

```
{
    setDB: function(db) {
        this.db = db;
    },
    getlist: function(callback, query) {
        this.db.find(query || {}, function (err, doc) { callback(doc) });
    }
}
```

So, no db by default. And since you attach something to the `app` in the initial pageload, you do get something.

But in your current update function, you attach stuff to the new app (`reqApp = req.app`), so now you're not talking to the original app, but another instance of it. And I think that your subsequent requests (after the update) get the scope all mixed up so lose the touch with the actual latest data.

Dynamic routes with Express.js -- is this even possible?

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