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Is it possible to return a list of specific values from a MongoDB query?
Yes, using map(). Let us first create a collection with documents −
> dblistOfSpecificValuesDemoinsertOne({"StudentName":"John"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5cefcc8fef71edecf6a1f6bb")
}
> dblistOfSpecificValuesDemoinsertOne({"StudentName":"Chris"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5cefcc94ef71edecf6a1f6bc")
}
> dblistOfSpecificValuesDemoinsertOne({"StudentName":"Robert"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5cefcc98ef71edecf6a1f6bd")
}
> dblistOfSpecificValuesDemoinsertOne({"StudentName":"David"});
{
"acknowledged" : true,
"insertedId" : ObjectId("5cefcc9cef71edecf6a1f6be")
}Following is the query to display all documents from a collection with the help of find() method −
> dblistOfSpecificValuesDemofind();
Output
{ "_id" : ObjectId("5cefcc8fef71edecf6a1f6bb"), "StudentName" : "John" }
{ "_id" : ObjectId("5cefcc94ef71edecf6a1f6bc"), "StudentName" : "Chris" }
{ "_id" : ObjectId("5cefcc98ef71edecf6a1f6bd"), "StudentName" : "Robert" }
{ "_id" : ObjectId("5cefcc9cef71edecf6a1f6be"), "StudentName" : "David" }Following is the query to return a list of specific values from a query −
> dblistOfSpecificValuesDemofind()map(function(myDocument){ return myDocumentStudentName });Output
[ "John", "Chris", "Robert", "David" ]
Updated on: 30-Jul-2019
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