I'm already scripting a lot of schema changes for the application as part of this upgrade/conversion process, so I just added queries to convert the -1 values to +1 for all my boolean columns, and that's a reasonable solution for my situation.
But for example, I had code like this:
var bucket = new RelationPredicateBucket();
bucket.PredicateExpression.AddWithAnd(MyTableFields.MyColumn == true);
Then use DataAdapter.FetchEntityCollection to retrieve entities.
This generates SQL like this:
Generated Sql query:
Query: SELECT ... FROM ... WHERE ( "MYSCHEMA"."MYTABLE"."MYCOLUMN" = :p1)
Parameter: :p1 : Int16. Length: 0. Precision: 0. Scale: 0. Direction: Input. Value: 1.
What I would want to see there is the generated query using "<>0" instead of "=1", but I assume that gets complicated because the DQE doesn't know this is supposed to be a boolean value rather than an integer.
(If I change the code so the Predicate uses "MyColumn!=false" then it works correctly (the SQL generated is "<>0") but this didn't seem like a maintainable workaround.)