In my Rails app I've run into an issue a couple times that I'd like to know how other people solve:
I have certain records where a value is optional, so some records have a value and some are null for that column.
If I order by that column on some databases the nulls sort first and on some databases the nulls sort last.
For instance, I have Photos which may or may not belong to a Collection, ie there are some Photos where collection_id=nil and some where collection_id=1 etc.
If I do Photo.order('collection_id desc) then on SQLite I get the nulls last but on PostgreSQL I get the nulls first.
Is there a nice, standard Rails way to handle this and get consistent performance across any database?
Adding arrays together will preserve order:
@nonull = Photo.where("collection_id is not null").order("collection_id desc")
@yesnull = Photo.where("collection_id is null")
@wanted = @nonull+@yesnull