"undefined is not a function" in nodejs/expressjs

I'm using 'express-namespace' to categorize my routing. Here is my code.

..
 9 var controllers = require('./controllers');
 10 require('express-namespace');
..
 46
 47 app.namespace('/json', function(){
 48     app.post('/', function(req, res, next){
 49         res.header('Content-Type', 'application/json');
 开发者_StackOverflow社区50         next();
 51     });
 52     /**
 53      * Map the controller objects and its actions
 54      * to the corresponding URL in lower case
 55      */
 56     for(var controller in controllers){
 57         app.namespace('/' + controller.toLowerCase(), function(){
 58             controller = controllers[controller];
 59             for(var action in controller){
 60                 app.post('/' + action.toLowerCase(), function(req,res){
 61                     action = controller[action];
 62                     action(req, function(result){
 63                         res.send(result);
 64                     });
 65                 });
 66             }
 67         });
 68     }
 69 });

and here is my ./controllers.js code:

...
 4 var Users = {
 5 };
 6
 7 Users.create = function(req, result){
...
 22 }
 23
 24 exports.Users = Users;
 25

My point is to move my controllers code into a single .js file and map all my controllers into corresponding lower-case URL so my app is pretty neat.

This works out pretty good for the first POST every time I run 'node app.js'. If I POST to the URL for the second time, the following exception occurs:

TypeError: undefined is not a function
   at CALL_NON_FUNCTION (native)
   at /home/carl/source/node/funner/app.js:62:21
   at callbacks (/usr/local/lib/node/.npm/express/2.4.6/package/lib/router/index.js:272:11)
   at param (/usr/local/lib/node/.npm/express/2.4.6/package/lib/router/index.js:246:11)
   at pass (/usr/local/lib/node/.npm/express/2.4.6/package/lib/router/index.js:253:5)
   at Router._dispatch (/usr/local/lib/node/.npm/express/2.4.6/package/lib/router/index.js:280:4)
   at Object.handle (/usr/local/lib/node/.npm/express/2.4.6/package/lib/router/index.js:45:10)
   at next (/usr/local/lib/node/.npm/connect/1.7.0/package/lib/http.js:201:15)
   at /usr/local/lib/node/.npm/connect/1.7.0/package/lib/middleware/session.js:323:9
   at /usr/local/lib/node/.npm/connect/1.7.0/package/lib/middleware/session.js:342:9

Can anyone give me a hint here?

I don't see a clear error, but I do see some dangerous javascript. for( key in obj ) statements should be filtered by hasOwnProperty ifs and it's important to use var statements to scope local variables in functions within loops.

 47 app.namespace('/json', function(){
 48     app.post('/', function(req, res, next){
 49         res.header('Content-Type', 'application/json');
 50         next();
 51     });
 52     /**
 53      * Map the controller objects and its actions
 54      * to the corresponding URL in lower case
 55      */
 56     for(var controller in controllers){
            **if(controller.hasOwnProperty(controller) {**
 57         app.namespace('/' + controller.toLowerCase(), function(){
 58             **var mycontroller** = controllers[controller];
 59             for(var action in mycontroller){
                    **if(mycontroller.hasOwnProperty(action) {**
 60                 app.post('/' + action.toLowerCase(), function(req,res){
 61                     **var myaction** = mycontroller[action];
 62                     myaction(req, function(result){
 63                         res.send(result);
 64                     });
 65                 });
                    }
 66             }
 67         });
            }
 68     }
 69 });

I haven't used express-namespace but I think you can just map the urls for the controllers as they come using req.params. Like so:

app.namespace('/json', function(){

  app.post('/:controller/:action', function(req, res, next){

    var controller = req.params.controller,
            action = req.params.action;

        controller[0] = controller[0].toUpperCase();

    if( controllers[ controller ][ action ] ){
      res.header('Content-Type', 'application/json');

      controllers[ controller ][ action ](req, function(result){
        res.send(result);
      });

    }
    else
      res.send('Action %s is not defined for the %s controller', action, controller);    


  });

});

And the same can be done for app.post('/:controller', ...);

Tell me if it works.

PD. I'm new to node+express.