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How to concatenate results in MongoDB?
You can concatenate results with the help of forEach(). Let us first create a collection with documents −
> db.concatenateDemo.insertOne({"Name":"John","Age":21});
{
"acknowledged" : true,
"insertedId" : ObjectId("5cc80dd88f9e6ff3eb0ce448")
}
> db.concatenateDemo.insertOne({"Name":"Carol","Age":23});
{
"acknowledged" : true,
"insertedId" : ObjectId("5cc80de18f9e6ff3eb0ce449")
}Following is the query to display all documents from a collection with the help of find() method −
> db.concatenateDemo.find().pretty();
This will produce the following output −
{
"_id" : ObjectId("5cc80dd88f9e6ff3eb0ce448"),
"Name" : "John",
"Age" : 21
}
{
"_id" : ObjectId("5cc80de18f9e6ff3eb0ce449"),
"Name" : "Carol",
"Age" : 23
}Here is the query to concatenate results −
> db.concatenateDemo.find().forEach( function (result) {result.NameAndAge = result.Name + ' ' + result.Age; printjson(result); } );This will produce the following output −
{
"_id" : ObjectId("5cc80dd88f9e6ff3eb0ce448"),
"Name" : "John",
"Age" : 21,
"NameAndAge" : "John 21"
}
{
"_id" : ObjectId("5cc80de18f9e6ff3eb0ce449"),
"Name" : "Carol",
"Age" : 23,
"NameAndAge" : "Carol 23"
}
Updated on: 30-Jul-2019
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