Mongoose 4.x“model.update（）”回调发生了变化

Question

Before mongoose 4.x, in update(), you can check the 2nd parameter in callback to see if the document is found. In example below, you can use "rowAffected" to see if there exists a document with username john.

model.update({ username: "john" }, { ... }, function(err, rowAffected){ 
    if (rowAffected) // document found

But now from mongoose 4.x, the 2nd parameter in callback becomes the raw output of MongoDB from update operation. So to find if document exists I have to do raw.n

model.update({ username: "john" }, { ... }, function(err, raw){ 
    if (raw.n) // document found

My question is are "rowAffected" and "raw.n" the same thing ? If so, is it safe to replace all rowAffected by raw.n when migrating from 3.x to 4.x?

Answer 1

Yes, they are the same thing. According to the 4.0 release notes :

#2552 : Upgraded mongodb driver to 2.0.x. Mongoose is a wrapper layer on top of the MongoDB node driver. The mongodb driver recently released version 2.0, which includes numerous performance and usability improvements. The new driver, however, introduces a few changes that affect the way you use Mongoose:

• If you are connecting to a replica set, you must specify the replicaSet option in the connection string.
• update returns a result object from the MongoDB server, rather than just the number affected. The second parameter to the callback will now look like { ok: 1, n: 3 } rather than simply the number affected.