Allow selection of all columns in a leaf preload by not specifying any column

internal/statements/select.go

@@ -98,6 +98,10 @@ func (statement *Statement) genColumnStr() string {
 			continue
 		}
 
+		if col.Association != nil {
+			continue
+		}
+
 		if buf.Len() != 0 {
 			buf.WriteString(", ")
 		}

preload.go

@@ -134,9 +134,14 @@ func (node *PreloadTreeNode) compute(session *Session, ownMap, pruneMap reflect.
 	}
 
 	refMap := node.association.MakeRefMap()
-	preloadSession := session.Engine().Cols(node.extraCols...).Where(cond)
+	preloadSession := session.Engine().Where(cond)
 	if node.preload != nil {
-		preloadSession.Cols(node.preload.cols...).Where(node.preload.cond)
+		if len(node.preload.cols) > 0 {
+			preloadSession.Cols(node.extraCols...).Cols(node.preload.cols...)
+		}
+		preloadSession.Where(node.preload.cond)
+	} else {
+		preloadSession.Cols(node.extraCols...)
 	}
 	if err := preloadSession.Find(refMap.Interface()); err != nil {
 		return err

preload_test.go

@@ -124,10 +124,12 @@ insert into employee_indication values (1,2), (1,3), (2,3), (2,4), (2,5), (3,5),
 			Subordinates: []*Employee{
 				{
 					Id:        3,
+					Name:      "Alice",
 					ManagerId: &[]int64{1}[0],
 					IndicatedBy: []*Employee{
 						{
-							Id: 1,
+							Id:   1,
+							Name: "John",
 							Indications: []*Employee{
 								{
 									Id:   2,