How to update record in MongoDB without replacing the existing fields?

Question

When I am update a record, it removes the existing fields and adds the new ones.

This was the record before the update:

{ "_id" : ObjectId("56a356863aa433ae37dc2cee"), "browser" : "Chrome", "version" : 47}

This was the command I executed:

db.collection('profiles')
  .update({ 
    '_id' : obj("56a356863aa433ae37dc2cee") }, 
    {"first_name" : first_name, "last_name" : last_name, "email" : email}, 
    function (err, result) {
      console.log(result);
  });

This was the record after I had executed the update command:

{ "_id" : ObjectId("56a356c9a08487ed3719e40a"), "first_name" : "kaushik", "last_name" : "makwana", "email" : "kdmakwana" }

Answer 1

Same as the updating existing collection field, $set will add a new fields if the specified field does not exist.

> db.foo.find()
> db.foo.insert({"test":"a"})
> db.foo.find()
{ "_id" : ObjectId("4e93037bbf6f1dd3a0a9541a"), "test" : "a" }
> item = db.foo.findOne()
{ "_id" : ObjectId("4e93037bbf6f1dd3a0a9541a"), "test" : "a" }
> db.foo.update({"_id" :ObjectId("4e93037bbf6f1dd3a0a9541a") },{$set : {"new_field":1}})
> db.foo.find()
{ "_id" : ObjectId("4e93037bbf6f1dd3a0a9541a"), "new_field" : 1, "test" : "a" }

Answer 2

use $set to update fields or add new fields. Your query should be:

db.collection('profiles').update(
    { 
    '_id' : obj("56a356863aa433ae37dc2cee")
    },
    { $set:{{"first_name" : first_name, "last_name" : last_name, "email" : email}} }, 

    function (err, result){
        console.log(result); 
    });