mongodb在单个数组文档中插入字段

Question

I have a document in mongodb that looks like this

{
   "_id": ObjectId("5378da275ad972a811c119fb"),
   "name": "test test",
   "fname": "test",
   "lname": "test",
   "phone": "13254355554",
   "user": "525518965ad972636d7aa0ae",
}

And i want to insert a new field for "employee_id" so the result should be exactly like this.

 {
   "_id": ObjectId("5378da275ad972a811c119fb"),
   "name": "test test",
   "fname": "test",
   "lname": "test",
   "employee_id": "09872",
   "phone": "13254355554",
   "user": "525518965ad972636d7aa0ae",
}

I have used $push and $addToSet but the results became an array like

"employee_id": {
     "0": "09872",
} 

Answer 1

Just use $set;

db.test.update(
      { _id:ObjectId("5378da275ad972a811c119fb") },    // Update this id only 
      { $set:{"employee_id": "09872"} }                // by setting employee_id
)