how do i get the key value instead of full object in mongoDB (node.js)

Question

while retrieving image name from my database, i am able to retrieve full object, but i just want the specific value.

Example while running the following code:

app.get("/data", function (req, res) {
  if (req.isAuthenticated()) {

    User.findById(req.user.id, function (err, foundUser) {

    Comment.find({userId:foundUser.id},{_id:0,imagename:1} ,function(err,imagename){
      if(err){
        console.log(error);
      }
      else{
        console.log(imagename);

        res.render("data", { EJS: a });
      }
    })
  })
  } else {
    res.redirect("/firstpage");
  }
});

when I log the image name, after else above I get following output

[ 
  { imagename: 'image:image-1589817207200.PNG' },
  { imagename: 'image-1589817409060.PNG' },
  { imagename: 'image-1589817473811.jpeg' }
]

While I just want to extract the value of the image that is (image-1589817207200.PNG' || image-1589817409060.PNG' || imagename: 'image-1589817473811.jpeg').

I spent days searching online,and i got many answers including one on StackOverflow,that said use Object.keys(imagename),but that just logged index number ( [ '0', '1', '2' ] ) which I don't want. I just want the specific image name.

Thanks in advance

Does this answer your question? [Retrieve only the queried element in an object array in MongoDB collection](https://stackoverflow.com/questions/3985214/retrieve-only-the-queried-element-in-an-object-array-in-mongodb-collection) As given over there you can get just wanted element from DB, rather than getting everything & finding for needed element in array using code ! — whoami - fakeFaceTrueSoul, May 18 '20 at 16:46
thanks alot for this,i tried this way before,but couldn't get the answer. below @max has done it correctly. — Riyazat Durrani, May 18 '20 at 17:19

max · Accepted Answer · 2020-05-18T16:32:34.980

1

you can map your response:

arr = [ 
    { imagename: 'image:image-1589817207200.PNG' },
    { imagename: 'image-1589817409060.PNG' },
    { imagename: 'image-1589817473811.jpeg' }
  ];

let result = arr.map(img => img.imagename);

console.log(result)

edited May 18 '20 at 16:32

answered May 18 '20 at 16:26

max

469
3
10

yes got the answer,thanks alot. much appreciated. would be nice if u can elaborate arr.map(img => img.imagename); line to me,as i am new to programming. – Riyazat Durrani May 18 '20 at 17:16
sorry by mistake it happned. just noticed after your comment. appologies – Riyazat Durrani May 20 '20 at 11:44

score 1 · Answer 2 · answered May 18 '20 at 16:36

1

Sadly, I cannot comment, but as far as I understand you want to get the value from each image object in the array and compare them (?).

You can just iterate over it and get each imagename value like this:

 imagename.forEach(imageObj => {
  if (imageObj.imagename === 'your value') {
    // your logic
  }
});

You can also select with a where clause directly via mongoose (consult https://mongoosejs.com/docs/api.html#model_Model.find for more)

answered May 18 '20 at 16:36

Timon

359
3
10

Most likely @max understood it correctly so you can pretty much ignore my answer :) – Timon May 18 '20 at 16:39
thanks alot for you time, although this was not i was looking for,but @max did get the answer correctly. thanku so much. – Riyazat Durrani May 18 '20 at 17:17

how do i get the key value instead of full object in mongoDB (node.js)

2 Answers2