Error handling with route

[pwielgolaski]

I would like to get information in my error handler what endpoint was handling it. The problem that I have is that when error handler is run req.baseUrl is not available

I wanted to use line like this

var endpoint = req.route ? (req.baseUrl + req.route.path) : '<no endpoint>';

but when route is mounted i.e at /users/ I can get only :id and empty baseUrl. I don't want to have information about individual request like /users/myname

[tunniclm]

I think the information you want gets reset when the router finishes processing a router/sub-app. I will take a closer look.

[wesleytodd]

Related and possible solution: #2864

Would that feature help you in this issue?

Also a similar discussion that might be good for reference: #2879

[tunniclm]

Didn't get to this today, will investigate tomorrow.

[tunniclm]

I learnt a bit more about the router while looking into this. Indeed the baseUrl is reset back to normal when next() is called.

I think there is a fairly simple change you could make to Express to make the baseUrl visible to the error handler, but I'm not sure whether there would be any unintended consequences to doing that.
In essence, it would be to save the baseUrl into req.routeBaseUrl at the same places the route is saved into req.route.

diff --git a/lib/router/index.js b/lib/router/index.js
index 504ed9c..3e5681b 100644
--- a/lib/router/index.js
+++ b/lib/router/index.js
@@ -259,6 +259,7 @@ proto.handle = function handle(req, res, out) {
     // store route for dispatch on change
     if (route) {
       req.route = route;
+      req.routeBaseUrl = req.baseUrl;
     }

     // Capture one-time layer values
diff --git a/lib/router/route.js b/lib/router/route.js
index 2788d7b..86b59db 100644
--- a/lib/router/route.js
+++ b/lib/router/route.js
@@ -108,6 +108,7 @@ Route.prototype.dispatch = function dispatch(req, res, done) {
   }

   req.route = this;
+  req.routeBaseUrl = req.baseUrl;

   next();

@expressjs/express: Any thoughts on that idea?

[pwielgolaski]

I like simplicity of this solution, at the moment I wrapped all my handlers function and rewrite baseUrl to lastBaseUrl, it works, but it is not clean solution.

[hacksparrow]

@tunniclm any unintended side effects should ideally be caught by the existing tests.

Looks like a useful feature. Maybe something for 5.x? @dougwilson your thoughts?

[dougwilson]

I think a best solution would be actually to make what is in req.route an entire object on it's own, and include things like baseUrl for that route inside that object, thus completely encapsulating all the route-based information you'd need.

Because this is a conversation regarding altering the router, the discussion is likely best moved over to https://github.com/pillarjs/router as the current state for any router changes is that changes to Express 4.x routing is landed in router 1.x and then cherry picked into this repository, otherwise landed in router 2.x, which is a direct Express 5.x dependency.

[hacksparrow]

@dougwilson that's a good suggestion. @tunniclm what do you say?

[tunniclm]

Yes, let's move this over. For 4.x I did not alter req.route so it would be back-compatible, but for 5.0 we can do whatever we like. :)