No need to make the caller supply the CAS flag in the binding statement

gocql_test/main.go

@@ -146,12 +146,11 @@ func insertCAS() error {
 
 	var titleCAS string
 	var revidCAS uuid.UUID
-	var casApplied bool
 
 	applied, err := session.Query(
 		`INSERT INTO cas_table (title, revid)
         VALUES (?,?) IF NOT EXISTS`,
-		title, revid).ScanCas(&casApplied, &titleCAS, &revidCAS)
+		title, revid).ScanCas(&titleCAS, &revidCAS)
 
 	if err != nil {
 		return err
@@ -164,7 +163,11 @@ func insertCAS() error {
 	applied, err = session.Query(
 		`INSERT INTO cas_table (title, revid)
         VALUES (?,?) IF NOT EXISTS`,
-		title, revid).ScanCas(&casApplied, &titleCAS, &revidCAS)
+		title, revid).ScanCas(&titleCAS, &revidCAS)
+
+	if err != nil {
+		return err
+	}
 
 	if applied {
 		return fmt.Errorf("Should NOT have applied update for existing random title %s", title)

session.go

@@ -176,47 +176,45 @@ func (q *Query) Scan(dest ...interface{}) error {
 // Otherwise the dest interface will not be bound and the function
 // will return true.
 func (q *Query) ScanCas(dest ...interface{}) (bool, error) {
-
-	// Copy and paste start
-	iter := q.Iter()
-	if iter.err != nil {
-		return false, iter.err
+	result := q.session.executeQuery(q)
+	if result.err != nil {
+		return false, result.err
 	}
-	if len(iter.rows) == 0 {
+	if len(result.rows) == 0 {
 		return false, ErrNotFound
 	}
-	// Copy and paste end
-
-	if iter.next != nil {
-		go iter.next.fetch()
-	}
 
-	switch len(iter.columns) {
+	switch len(result.columns) {
 	case 1:
 		{
 			// The CAS operation was applied
 			return true, nil
 		}
-	case len(dest):
+	case len(dest) + 1:
 		{
-			// Copy and paste start - should this get merged into the upstream, this should
-			// be factored out
-			for i := 0; i < len(iter.columns); i++ {
-				err := Unmarshal(iter.columns[i].TypeInfo, iter.rows[iter.pos][i], dest[i])
+			// The CAS operation was NOT applied
+			// In this case, the result will return the entire row from the database
+			// in addition a flag in indicating the
+			var applied bool
+			Unmarshal(result.columns[0].TypeInfo, result.rows[result.pos][0], &applied)
+
+			if applied {
+				return applied, errors.New("Expected unapplied CAS statement, but received applied CAS statement")
+			}
+
+			for i := 1; i < len(result.columns); i++ {
+				err := Unmarshal(result.columns[i].TypeInfo, result.rows[result.pos][i], dest[i-1])
 				if err != nil {
 					return false, err
 				}
 			}
-			// Copy and paste end
-			return false, nil
+			return false, result.err
 		}
 	default:
 		{
-			return false, errors.New("count mismatch")
+			return false, fmt.Errorf("Expected %d + 1 columns, but received %d columns", len(dest), len(result.columns))
 		}
 	}
-
-	return false, iter.Close()
 }
 
 // Iter represents an iterator that can be used to iterate over all rows that