MongoDB / Mongoose-通过执行加法更新文档中的数字

Question

I have a mongoDB collection where I store time & costs saved. When the users enter the data for the first time the document kinda looks like this:

{ "fullName" : "john smith",
  "company" : "xyz",
  "email" : "john.smith@xyz.com",
  "timeSaved" : 50 //this is in minutes
  "moneySaved" : 10 //this is in dollars
}

Now when the user enters the data again I find if a document already exists for this user and if it does I get it.

This time the user entered:

1. Time Saved 55
2. money Saved 10

I want to add the new values to the existing values. So after the documents shows this:

"timeSaved" : 105 // old 50 + new 55
"moneySaved" : 20 // old 10 + new 10

Whats the best way to achieve this. Is there an inbuilt function in mongodb/mongoose that can help with this.

Answer 1

You can do this by $inc operator. The $inc operator increments a field by a specified value

For example in your case:

UserModel.update(
    SomeFindCriteria,
   { $inc: { timeSaved: newTimeSaved, moneySaved: newMoneySaved } }
)