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Create array with MongoDB query?
You can use the concept of toArray() to create array. Following is the syntax −
db.yourCollectonName.find({}, {yourFieldName:1}).toArray();
Let us create a collection with documents −
> db.createArrayDemo.insertOne({"UserName":"Chris"}); { "acknowledged" : true, "insertedId" : ObjectId("5cbd6461de8cc557214c0e00") } > db.createArrayDemo.insertOne({"UserName":"David"}); { "acknowledged" : true, "insertedId" : ObjectId("5cbd6467de8cc557214c0e01") } > db.createArrayDemo.insertOne({"UserName":"Robert"}); { "acknowledged" : true, "insertedId" : ObjectId("5cbd646cde8cc557214c0e02") } > db.createArrayDemo.insertOne({"UserName":"Sam"}); { "acknowledged" : true, "insertedId" : ObjectId("5cbd6470de8cc557214c0e03") }
Display all documents from a collection with the help of find() method −
> db.createArrayDemo.find().pretty();
This will produce the following output −
{ "_id" : ObjectId("5cbd6461de8cc557214c0e00"), "UserName" : "Chris" } { "_id" : ObjectId("5cbd6467de8cc557214c0e01"), "UserName" : "David" } { "_id" : ObjectId("5cbd646cde8cc557214c0e02"), "UserName" : "Robert" } { "_id" : ObjectId("5cbd6470de8cc557214c0e03"), "UserName" : "Sam" }
Case 1 − Create array with MongoDB.
If you want to create an array of field UserName and do not want the field _id, use the below query.
> db.createArrayDemo.find({},{_id:0}, {UserName:1}).toArray();
This will produce the following output −
[ { "UserName" : "Chris" }, { "UserName" : "David" }, { "UserName" : "Robert" }, { "UserName" : "Sam" } ]
Case 2 − Create array with MongoDB with field name_id only
If you want to create an array with field name _id only, use the below query.
> db.createArrayDemo.find({}, {_id:1}).toArray();
This will produce the following output −
[ { "_id" : ObjectId("5cbd6461de8cc557214c0e00") }, { "_id" : ObjectId("5cbd6467de8cc557214c0e01") }, { "_id" : ObjectId("5cbd646cde8cc557214c0e02") }, { "_id" : ObjectId("5cbd6470de8cc557214c0e03") } ]
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