Node.js Object [object Object] has no method error

Question

I am using Express.js for my app and mongodb for database (also mongodb Nativ driver).

I created a model with two functions, for getting posts and comments:

// Get single Post
exports.posts = function(id,callback){

    MongoClient.connect(url, function (err, db) {
      if (err) {
        console.log('Unable to connect to the mongoDB server. Error:', err);
      } else {

        console.log('Connection established to', url);

        var collection = db.collection('posts');

        collection.find({psotId:id}).limit(1).toArray(function (err, result) {
          if (err) {
            return callback(new Error("An error has occured"));
          } else {
            callback(null,result);
          }
          db.close();
        });
      }
    });

}

// Get post comments
exports.comments = function(id,callback){

    MongoClient.connect(url, function (err, db) {
      if (err) {
        console.log('Unable to connect to the mongoDB server. Error:', err);
      } else {      
        console.log('Connection established to', url);
        var collection = db.collection('comments');
        collection.find({postId:id}).toArray(function (err, result) {
          if (err) {
            return callback(new Error("An error has occured"));
          } 
          else {        
            callback(null,result);
          }
          db.close();
        });
      }
    });

}

and I created a route to show single post:

var post = require('../models/post');
 //Get single post
router.get('/post/:postId',function(req,res, next){

    var id = parseInt(req.params.postId);
    post.posts(id,function(err,post){
        if(err){
            console.log(err)
        }else{
            post.comments(post[0].id,function(err,comments){
                if(err){
                    console.log(err)
                }
                else{
                    res.render('blogPost',{post:post,comments:comments})
                }
            })
        }
    })

})

When I run this code I get this error:

TypeError: Object [object Object] has no method 'comments'

When I use this two function separately its work fine:

I mean like this :

var post = require('../models/post');
 //Get single post
router.get('/post/:postId',function(req,res, next){

    var id = parseInt(req.params.postId);
    post.posts(id,function(err,post){
        if(err){
            console.log(err)
        }else{
           res.render('blogPost',{post:post})   
        }
    })

})





     //Get post comments
router.get('/post/1',function(req,res, next){

    post.comments(1,function(err,comments){
        if(err){
            console.log(err)
        }else{
           res.render('blogPost',{comments:comments})   
        }
    })

})

But when I use post.comments as callback for post.posts I get an error.

I wants know why this happening? After some research I couldn't find a solution and I an getting confused.

Well, it seems the post object doesn't hold a method comments. What might post be? — MinusFour
– MinusFour, Commented Sep 13, 2015 at 13:53
@MinusFour i updated questions, as you can see , i required my model as var post = require('../models/post'); so post.comments ref to exports.comments {...} in my model. — user1086010
– user1086010, Commented Sep 13, 2015 at 13:59

DevAlien · Accepted Answer · 2015-09-13 15:04:49Z

2

In your source code you have the following:

var post = require('../models/post');
 //Get single post
router.get('/post/:postId',function(req,res, next){

    var id = parseInt(req.params.postId);
    post.posts(id,function(err,post){
        if(err){
            console.log(err)
        }else{
            post.comments(post[0].id,function(err,comments){
                if(err){
                    console.log(err)
                }
                else{
                    res.render('blogPost',{post:post,comments:comments})
                }
            })
        }
    })

})

when you are calling post.posts you have a callback and there you have a return value which you called post (which it is the same variable name of var post = require('../models/post');

Basically change it in the callback like this:

var post = require('../models/post');
 //Get single post
router.get('/post/:postId',function(req,res, next){

    var id = parseInt(req.params.postId);
    post.posts(id,function(err,posts){ //HERE changed post into posts
        if(err){
            console.log(err)
        }else{
            post.comments(posts[0].id,function(err,comments){
                if(err){
                    console.log(err)
                }
                else{
                    res.render('blogPost',{post:posts,comments:comments})
                }
            })
        }
    })

})

EDIT: for better understanding I would change var post = require('../models/post'); into var postModel = require('../models/post'); SO it is much more understandable

EDIT 2: since he posted the real version code

Basically you have the same problem, line 37 of route.js is overriding the movie variable. You have to call the variable that comes back form the callback with another name, for example movieslike you used to do in the other 2 above.

router.get('/m/:movieId',function(req,res, next){

    var id = parseInt(req.params.movieId);
    movie.get(id,function(err,movies){
        if(err){
            console.log(err)
        }else{
            movie.subtitles(movies[0].imdb,function(err,subs){
                if(err){
                    console.log(err)
                }
                else{
                    res.render('moviePage',{movie:movies,subtitles:subs})
                }
            })
        }
    })

})

edited Sep 13, 2015 at 15:04

answered Sep 13, 2015 at 14:05

DevAlien

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6 Comments

user1086010 Over a year ago

still get same error, i dont think that would be problem because when i run post.posts without post.comments in callback its work just fine.

DevAlien Over a year ago

Yes, but you override the variable. you are assign the variable post on what you get from the post.posts. When you do post.posts(id, function(err, post) { inside that function, you override the post variable which will become an array (the result of post.post, which clearly has no method comments)

user1086010 Over a year ago

my source code is difference , here you can see source code

DevAlien Over a year ago

Check the EDIT 2 in this answer;)

DevAlien Over a year ago

Where do you change movie to movies, I gave you already the modified code. you make confusion with variable names, this is why i suggested to change the model variable to moviesModel var moviesModel = require('../models/movie'); but with this you have to change it everywhere

|

micah · Accepted Answer · 2015-09-13 13:48:35Z

0

If you copy-pasted this from your source then its because you mispelled the method.

post.commencts

should be

post.comments

answered Sep 13, 2015 at 13:48

micah

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