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Express - Conditional Routing

At my website.com/v2/bridge/:locationId/process endpoint, the incoming req.body looks like this:
{
choice: 'a',
data: [
{
...
},
...
]
}
I want to access a particular route depending on what the value of req.body.choice is. If req.body.choice === 'a' then I want to go on to website.com/v2/bridge/:locationId/process/choiceA with the same req being passed on.
I don't know what middleware I need to use to accomplish that. I don't know if that is even possible.
My extremely simplified routes:
// website.com/v2/bridge
const proc = require('./process');
router.use('/:locationId/process', proc);
module.exports = router;
// website.com/v2/bridge/56/process
router.use(function (req, res, next) {
// ?????????????????????????
next();
});
const choiceA = require('./choice-a');
const choiceB = require('./choice-b');
router.use('/choice-a', choiceA);
router.use('/choice-b', choiceB);
module.exports = router;
// website.com/v2/bridge/56/process/choice-a
router.post('/', function (req, res) {
res.send('I got here.');
return;
});
module.exports = router;
What middleware function do I need to include to conditionally route my request? I am trying to avoid one giant function with if statements that process different things according to the value of req.body.choice.

This will be little trickier for you...give it a try
router.use(function (req, res, next) {
req.path = "/" + "choice-"+req.body.choice
req.url = "/" + "choice-"+req.body.choice
next();
});
now it'will do the request to the end point you want

As part of finding the answer for the same question, I came across with this question, which didn't settle my mind by messing with the req.url, so here's how I got it done (I know it's a long delay, but better late than never):
When you're dealing with routers, and you want to make a condition to decide whether to use, you can do it with two ways (according to expressjs doc), and let's learn them by examples
1. Skipping between routes
function skipThisRouteMiddleware (req, res, next) {
if (true === isAmazingValidation) {
return next('route');
}
return next();
}
router.get('/user/:id',
skipThisRouteMiddleware,
getUserV1 // TBD - your old route
)
router.get('/user/:id',
getUserV2 // TBD - your new route
)
In the case above, when you have two routes, and you want to conditionally pick one of them, it can be done by specifying a middleware that makes the validation for the first route only, and when needed, it triggers next('route') which skip to the next matching route, please note that you must specify METHOD and not generally app.use()
2. Skipping between routers
// routers/index.js
const mainRouter = express.Router();
mainRouter.use(oldRouter);
mainRouter.use(newRouter);
// routers/old.js
const oldRouter = express.Router();
function canUpgradeToNewRouter (req, res, next) {
if (true === isAmazingValidation) {
return next('router'); // now it's 'router' and not 'route'
}
return next();
}
oldRouter.use(canUpgradeToNewRouter);
// routers/new.js
const newRouter = express.Router();
newRouter.use(...);
In this case, you have two different routers, and you want to conditionally pick one of them. for this case, you'll have to create a parent router (mainRouter) and two nested routers (oldRouter, newRouter).
The trick here is that the oldRouter tries to run a middleware validation that tries to "upgrade" the requester to the new shiny router, if the condition is true, it will skip the whole oldRouter, and pass the stick to the parent router mainRouter to continue matching routes to this request (the magic - next('router')), which eventually pick the upcoming newRouter
In both methods, we let the first route to make the logic and choose between itself and the others, that's a different perception (a bit)

It is possible to enhance the express.js req and res variables without using a middleware function?

I'm working in a restful service using express.js and i want to enhance the req and res variables so for example you could write something like
app.use(function (req, res, next) {
res.Ok = function (data) {
res.status(200).send(data);
};
res.InternalError = function (err) {
res.status(500).send(err);
};
});
And later
router.get('/foo', function (req, res) {
res.Ok('foo');
})
This will send 'foo' in the body of the response and set the status code to 200 and is working perfectly.
My first question is if it is possible to add such functionality without a middleware function, lets say in a property or the prototype of the app variable?
The second question is if there are performance issues if you add many functionality with middleware functions at the app level. Are this functions attached to the request and response object per request or once on the application startup?
I know the Sails framework already do this but I'm wondering if they use middleware functions as well.

I keep digging and turns out that the request and response object are exposed in express using the __proto__ property.
var express = require('express'),
app = express();
app.response.__proto__.foo = function (data) {
this.status(200).send(data);
};
And later in the router
router.get('/foo', function (req, res, next) {
res.foo('test');
});
This will print test in your browser so it is possible to add functionality without using any middleware.
Note: I'm sure there are some drawbacks to this approach (overwriting express predefined properties, for example) but for testing purposes and adding very simple functionality I think is slightly better in terms of performance.

I'm not aware of any other way than using middleware. But in my opinion you could do the following to achieve nearly the same thing.
// Some Route
router.get('/foo', function(req, res, next) {
// ...
if(err) {
res.status(500);
return next(err);
}
return res.send('ok');
});
// Another route
router.get('/bar', function(req, res, next) {
// ...
if(badUserId) {
res.status(400);
return next('Invalid userId.');
}
req.result = 'hello';
return next();
});
router.use(function(req, res) {
// I prefer to send the result in the route but an
// approach like this could work
return res.send(req.result);
});
// Error Middleware
router.use(function(err, req, res, next) {
if(res.statusCode === 500) {
// Log the error here
return res.send('Internal server error');
} else {
return res.send(err);
}
});

SailsJs controller context

Does anybody know proper way to pass context to sails controllers action?
Here is my case why I want to do it:
--- AbstractPageController.js ---
module.exports = {
_getPageData: function(req, res) {
return {
data: {
title: this._getTitle(req, res), // if do nothing "this" is global object
menu: this._getMenu(req, res)
}
};
},
_getTitle: function(req, res) { return 'Cool Page'; },
_getMenu: function(req, res) { return [{ href: '/logout' }]; }
};
--- ConcretePageController.js ---
var _ = require('lodash');
_super = require('./AbstractPageController.js');
module.exports = _.merge({}, _super, {
'main': function(req, res) {
res.view('pageTemplate', this._getPageData(req, res));
},
_getTitle: function(req, res) {
return 'Absolutely - ' + _super._getTitle(req, res);
},
_getMenu: function(req, res) {
return [{ href: '/main/'}].concat(_super._getMenu(req, res));
}
});
That's why I need context.
For this particular case I found this solution:
--- routes.js ---
var concreteController = require('../api/controllers/ConcretePageController.js');
module.exports.routes = {
'/concrete_page': function(req, res) { concreteController.main(req, res); }
}
But it seems a little bit ugly and sails hooks (for example policies) stop works.
I was thinking about the other way. The main point of this, is to move all logic to services and to use a simple inheritance. But this seems strange for me too
Any ideas about a better way to reach the cases I have wrote?
P.S. All code I have wrote above is just an example.

I think you whant to pre-set some data to send to view template, right?
is yes you can use one Before hook ( like midleware ) or sails police
I use the sails hook for preload sails features from npm modules in we-plugin https://github.com/wejs/we-plugin
Check this hook for how load user locale in all requests after controllers :
Link: https://github.com/wejs/we-example/blob/master/api/hooks/we-locale/index.js#L15

You should just reference the controller directly
sails.controllers.yourControllerName.getTitle()
https://stackoverflow.com/a/20994036/1821723

Express js routes url to correct page

URL pattern is www.example.com/product-name/pid_010101. URL's first segment is Product name and second segment is Product number. My app router code is below
app.get("/:name?/:id", routes.index);
Now my all urls redirect to same page. For example some url like www.example.com/homepage/banner.html also redirect to www.example.com/product-name/pid_010101
Need to add some Filters in router. How to route the url to correct page?

I assume your routes will be:
/coffeemaker/pid_0101222
/bluemarker/pid_121121
etc. ?
You can use regular expressions for this OR
this is an example of in method filtering:
app.get('/rest/:collection', function(req, res) {
return routes.rest[req.params.collection](req, res);
});
in routes object:
exports.rest = {
tweets: function(req, res) {
return twitter.data.load(function(data) {
return res.json(data);
}, config.site.tag, req);
},
pics: function(req, res) {
return instagram.data.load(function(data) {
return res.json(data);
}, config.site.tag, req);
},
repos: function(req, res) {
return github.data.load(function(data) {
return res.json(data);
}, req);
},
links: function(req, res) {
return delicious.data.load(function(data) {
return res.json(data);
}, config.site.tag, req);
}
};
:colection is then tweets, pics , or links string
Can you make a list of all your pages?
Maybe I can help you with your routes...

This is because of /homepage/banner.html complies to your route as well.
Therefore you must also specify those routes you want to trigger.
Say for example you have a welcome page.(/welcome/guest) or something like that.
You can add another route above the general route. specific for that page.
app.get("/welcome/guest", routes.welcome);
Now this is too much work for all your pages. So you can avoid this with a couple of techniques, one would be to put a static part in the url say:
app.get("/product/:name?/:id", routes.product);

I don't really get your problem. Is /homepage/banner.html a static page? Middlewares work like a filter, you can simply put express.static above express.router:
app.use(express.static('public'));
...
app.use(app.router);
app.get("/:name?/:id", routes.index);
banner.html is in (APP_DIR)/public/homepage/banner.html

Write own middleware function that handles the legacy URLs, and place it above the Express router.
app.use(function(req, res, next) {
if (legacySystemHandles(req.url)) {
// do legacy stuff
}
else next(); // pass to the next middleware function
});
app.use(app.router);

NodeJS supertest access to session object

I'm testing my Node.js application with supertest. In my controller I access the session object. In order to make a valid request this session object needs to be filled with some data.
Controller
// determine whether it is user's own profile or not
var ownProfile = userId == req.session.user._id ? true : false;
Test
it('profile', function (done) {
testUserOne.save(function(error, user){
request
.agent(server)
.get('/profile?userId=' + user._id)
.expect('Content-Type', /html/)
.expect(200)
.expect(/Profile/)
.end(done);
})
});
Question
How can I mock the req/session object?

just use as sub-app, and call your authenticated() at parent-app:
var mockApp = express();
mockApp.use(session);
mockApp.all('*', function(req, res, next) {
//authenticated(req, res, next);
//OR
req.session.uid = 'mock uid';
next();
});
mockApp.use(app);
all your routes will be authenticated before matched!

This new lib should do the trick:
https://github.com/rjz/supertest-session
You might also have a look at superagent that is part of supertest. Here's a nice tutorial on this:
http://jaketrent.com/post/authenticated-supertest-tests/
Don't want another lib? Try this one ...
https://gist.github.com/joaoneto/5152248