Question

Using MongoDB and the latest 10gen C# driver (CSharpDriver-1.3.1.4349), I am trying to do an “in place” update and get back the # of documents effected in the result.

public static long SaveListings(string state, bool isActive, DateTime updateDate)
{
    var result = Collection().Update(
    Query.And(
        Query.EQ("State", state), 
        Query.And(
            Query.EQ("IsActive", isActive),
            Query.LT("UpdateDate", updateDate))),
    Update.Set("IsActive", false), UpdateFlags.Multi);
    return result != null ? result.DocumentsAffected : -1;
}

The result is null for some reason. If I were doing this from the console, I could get the number of rows effected by doing this:

db.Listing.update( { State: state.Abbreviation, IsActive: true, UpdateDate: { $lt: expiredDate } }, { $set: { IsActive: false } }, false, true);
var numRows = db.getLastErrorObj().n;

Any idea what I’m doing wrong or is this a bug in the C# driver?

Answer 1

Update contains overloaded method that take SafeMode. Just add it to your code as fourth parameter to your update and should be not null:

...
UpdateFlags.Multi,
SafeMode.True);

That’s not driver bug, it work as expected. Mongodb does not wait for document if get inserted without safe mode (therefore driver return null), but if you saying SafeMode = true — you force mongodb wait until document get inserted.