After applying the find operation in mongodb.. i get the following list of documents..

  db.users.find(....)

i got:

 { "text" : "Hey" }
 { "text" : "Hi" }
 { "text" : "Hello" }
 { "text" : "yes" }

How can i convert it into

 ["Hey","Hi","Hello","yes"].

i tried

 db.users.find(...).map( function(u) { return "u.text"; } )

but it is giving error!

After applying the find operation in mongodb.. i get the following list of documents..

  db.users.find(....)

i got:

 { "text" : "Hey" }
 { "text" : "Hi" }
 { "text" : "Hello" }
 { "text" : "yes" }

How can i convert it into

 ["Hey","Hi","Hello","yes"].

i tried

 db.users.find(...).map( function(u) { return "u.text"; } )

but it is giving error!

• javascript
• mongodb
• database
• nosql

• And in SQL ( as opposed to "noSQL" ) you do that how? This actually is way to broad a question to be constructive to anyone here as well as being impossible without post processing in any environment. – Neil Lunn Commented May 15, 2014 at 11:00
• sorry, but i didn't get you.. what are you trying to say – shashank Commented May 15, 2014 at 11:03
• i tried db.users.find(...).map( function(u) { return "u.text"; } ) but it is giving error! – shashank Commented May 15, 2014 at 11:05
• And usage such as map as you described above is called "post processing". Also you need to learn how to edit your question here rather than supply relevant information in comments. – Neil Lunn Commented May 15, 2014 at 11:09
• so why this command is giving error? and whats the correct method to di it? – shashank Commented May 15, 2014 at 11:14

6 Answers 6

Not sure what you language implementation is but the basic concept is:

var result = []
db.users.find().forEach(function(u) { result.push(u.text) })

And the returned value to result is:

["Hey","Hi","Hello","yes"]

At first db.users.find(...).map() didn't work because db.users.find(...) doesn't return you a real array.

So you need to convert to array at first.

db.users.find(...).toArray()

Then if you apply map() function will work

  db.users.find(...).toArray().map( function(u) { return u.text ; } )

Another simple trick is using .forEach()

This will do the trick

var cursor = db.users.find(...); // returns cursor object which is a pointer to result set

var results = [];
cursor.forEach(
  function(row) {
     results.push(row.text);
  });

results //results will contain the values

Another option is simply to use distinct:

db.users.distinct("first_name");

Would return:

[
  "John",
  "Jennifer",
  ...
]

you can use

var u=db.users.find({...},{text:1,_id:0})
while(u.hasNext()){print(u.Next().text);}

The correct answer here is the method .distinct() (docs)

In your case try it like this:

db.users.find(....).distinct('text')

That will return only the values.

best way is :

db.users.distinct("text");


["Hey","Hi","Hello","yes"].

You will get further information regargding this topic here : mongodb distinct