Want a sub document which is present in document, from MongoDB Database

Question

I have a Json data stored in my MongoDB database as showing below,

{
        "_id" : ObjectId("5f17109a9013adc57942af2a"),
        "name" : "Demo Name",
        "dob" : "04/01/2000",
        "phone" : "1234567890",
        "email" : "[email protected]",
        "password" : "0987",
        "cPass" : "0987",
        "location" : "Civil line, Mumbai"
}

And I only want an name (sub document) i.e Demo Name here from this whole document:

: Demo Name 

I'm writing this query:

var employ = await coll.findOne( { "email": "[email protected]" } );

But it gives me whole document in var employ. I only want name in var employ. How can I do that with Mongo Dart.

Answer 1

This query finds the element whose email value is matched with "[email protected]" and after finding element, It is going to exclude the fields i.e _id, dob, phone, email, password, cPass and location. The value remains is "Demo Name" along with it's key.

 var employ = await coll
              .find(where.match("email", "[email protected]").excludeFields([
                "_id",
                "dob",
                "phone",
                "email",
                "password",
                "cPass",
                "location",
              ]))
              .toList();

For removing key we have to use the following code.

var arrayEle = employ[0];          // This statement can store the value in arrayEle from zeroth position.
var empName = arrayEle['name'];    // This statement can remove the key "name" and only value of the key i.e "Demo Name" gets stored in empName variable.   
  print(empName);                  // This statment print the value stored in empName which is "Demo Name".