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Include all existing fields and add new fields to document in MongoDB?
You can achieve this with the help of $addFields operator. To understand the concept, let us create a collection with the document. The query to create a collection with a document is as follows −
> db.addFieldDemo.insertOne({"EmployeeId":101,"EmployeeName":"Larry","EmployeeDetails":{
"EmployeeSalary":65000,"EmployeeCity":"New York","Message":"Hi"}});
{
"acknowledged" : true,
"insertedId" : ObjectId("5c7f654d8d10a061296a3c44")
}Display all documents from a collection with the help of find() method. The query is as follows −
> db.addFieldDemo.find().pretty();
The following is the output −
{
"_id" : ObjectId("5c7f654d8d10a061296a3c44"),
"EmployeeId" : 101,
"EmployeeName" : "Larry",
"EmployeeDetails" : {
"EmployeeSalary" : 65000,
"EmployeeCity" : "New York",
"Message" : "Hi"
}
}Here is the query to include all existing fields and add new fields to document in MongoDB −
> db.addFieldDemo.aggregate([ { "$addFields": { "EmployeeBasicSalary":"$EmployeeDetails.EmployeeSalary" } } ]).pretty();The following is the output −
{
"_id" : ObjectId("5c7f654d8d10a061296a3c44"),
"EmployeeId" : 101,
"EmployeeName" : "Larry",
"EmployeeDetails" : {
"EmployeeSalary" : 65000,
"EmployeeCity" : "New York",
"Message" : "Hi"
},
"EmployeeBasicSalary" : 65000
}Look at the sample output, “EmployeeBasicSalary” has been added.
Updated on: 30-Jul-2019
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