Error handling in SalatDAO

[randhindi]

Hi Rose

Looking at the SalatDAO source, I noticed that you only check for an error by testing error.ok(). But Mongo will sometimes return ok() even though an error occurred.

For example, when trying to insert a document with an _id that already exists, the WriteResult.getLastError.ok() == true, but a new key "err" is added to the writeResult with the description of the error. 

Just in case this is something you might find useful, I use the following to test for an error upon inserting:

val error = wr.getLastError

if (error != null && (!error.ok() || error.contains("err"))) {

    None

}

else {

    dbo.getAs[ObjectId]("_id")

}

Also, is there any reason why you used getLastCachedError instead of getLastError? The latter will get the cached error if it exists, but fetch the error if its not cached.

Cheers

Rand

[rktoomey]

On advice at the time from 10gen. The plethora of different ways to
check for an error is rather deplorable, actually.

[randhindi]

Indeed, the way mongo deals with errors is rather confusing, and not very well documented!