MongoDB - how to pass data through find().count()?

Question

I am practicing building a simple Express app with MongoDB. I created an endpoint that will search for a user by name and then render the page with the stored data from the DB. I tried to integrate some code to handle when a profile is not found, but it breaks the app.

This code works- the profile page renders as expected:

app.get('/profiles/:name', (req, res) => {
    // calling the model
    Profile
        .find({ "name.first": req.params.name })
        .then(profileArray => {
            let profile = profileArray[0];
            let img =
                `<img class="ui rounded image" src="http://api.adorable.io/avatar/250/${profile.name.first}${profile.age}" />`
            res.render('profile', { profile, img });
        })
        .catch(error => {

            if (error.reason === "ValidationError") {
                console.log(error);
                let response404 = error;
                res.render('add', { response404 });
            }
            else {
                console.log(error);
                res.render('add');
            }

        });
});

But when I integrate the following code- between find() and then() - it breaks the app:

    .count()
    .then(count => {
        if (count < 1) {
            return Promise.reject({
                code: 404,
                reason: "ValidationError",
                message: "Profile not found. Please create a profile."
            })
        };
    })

Here is the full endpoint code with the snippet that causes the crash:

app.get('/profiles/:name', (req, res) => {
    // calling the model
    Profile
        .find({ "name.first": req.params.name })
        .count()
        .then(count => {
            if (count < 1) {
                return Promise.reject({
                    code: 404,
                    reason: "ValidationError",
                    message: "Profile not found. Please create a profile."
                })
            };
        })
        .then(profileArray => {
            let profile = profileArray[0];
            let img =
                `<img class="ui rounded image" src="http://api.adorable.io/avatar/250/${profile.name.first}${profile.age}" />`
            res.render('profile', { profile, img });
        })
        .catch(error => {

            if (error.reason === "ValidationError") {
                console.log(error);
                let response404 = error;
                res.render('add', { response404 });
            }
            else {
                console.log(error);
                res.render('add');
            }

        });
});

It throws this error: "TypeError: Cannot read property '0' of undefined". It is referring to the second then() where I am trying to access the array returned from find().

It seems like the data from find() is getting lost. How can I pass the found document through count() and the first then()?

One thing to note. When I integrate the error handling code, I reject the promise and render a new page with a form. That part works, but when trying to render the page with a name that does exist in the DB it breaks. I'm losing the data somewhere along the chain. Let me know if you need anything clarified. Thanks.

Try to check if the count variable getting the proper value from promise — zb22, Jan 27 '18 at 08:01
yeah it gets the expected value. I console logged count just before the condition and inside it. It never enters the if condition when a profile is found, which is expected. So if a profile is found, then how do I continue? It seems to stop there instead of continue to the next promise in the chain. — bprdev, Jan 27 '18 at 08:11
When you doing 'find' and then 'count', you losing the result of 'find', see this: https://stackoverflow.com/questions/35443821/find-and-count-elements-of-collection-with-mongoose — zb22, Jan 27 '18 at 08:28
@zb22 good find. I gave you an upvote. However, already accepted an answer. Thanks for the help. — bprdev, Jan 27 '18 at 08:34

score 3 · Accepted Answer · edited Jan 27 '18 at 09:00

there is another way to do this.

Profile.find({ "name.first": req.params.name })
.then((docs) => {
  if(docs.length < 1) {
    return Promise.reject({
         code: 404,
         reason: "ValidationError",
         message: "Profile not found. Please create a profile."
   })
   let profile = docs[0];
   let img =`<img class="ui rounded image" src="http://api.adorable.io/avatar/250/${profile.name.first}${profile.age}" />`
        res.render('profile', { profile, img });
  })
   .catch(error => {
        if (error.reason === "ValidationError") {
            console.log(error);
            let response404 = error;
            res.render('add', { response404 });
        }
        else {
            console.log(error);
            res.render('add');
        }
    });
});

you can get the count of docs by using docs.length and the docs contain the data returned by mongoDB. This is an alternate approach.

oh yeah because find() returns an array. I should have thought of that! But that is why I love this site. Thanks for the help. I am happy with this alternate approach. — bprdev, Jan 27 '18 at 08:32
I made an edit, in case this thread is helpful to someone in the future. — bprdev, Jan 27 '18 at 08:44

MongoDB - how to pass data through find().count()?

1 Answers1