Add force index query mod for select query.

Fix eager loading casting for nested levels.

queries/eager_load.go

@@ -206,9 +206,16 @@ func (l loadRelationshipState) loadRelationshipsRecurse(depth int, obj reflect.V
 	}
 
 	bkind := kindStruct
-	if reflect.Indirect(loadedObject).Kind() != reflect.Struct {
+	if derefed := reflect.Indirect(loadedObject); derefed.Kind() != reflect.Struct {
 		bkind = kindPtrSliceStruct
-		loadedObject = loadedObject.Addr()
+
+		// Convert away any helper slice types
+		// elemType is *elem (from []*elem or helperSliceType)
+		// sliceType is *[]*elem
+		elemType := derefed.Type().Elem()
+		sliceType := reflect.PtrTo(reflect.SliceOf(elemType))
+
+		loadedObject = loadedObject.Addr().Convert(sliceType)
 	}
 	return l.loadRelationships(depth+1, loadedObject.Interface(), bkind)
 }
@@ -241,6 +248,9 @@ func collectLoaded(key string, loadingFrom reflect.Value) (reflect.Value, bindKi
 	if loadedType.Elem().Kind() == reflect.Struct {
 		bkind = kindStruct
 		loadedType = reflect.SliceOf(loadedType)
+	} else {
+		// Ensure that we get rid of all the helper "XSlice" types
+		loadedType = reflect.SliceOf(loadedType.Elem())
 	}
 
 	collection := reflect.MakeSlice(loadedType, 0, 0)

queries/qm/query_mods.go

@@ -123,6 +123,13 @@ func From(from string) QueryMod {
 	}
 }
 
+func ForceIndex( index string) QueryMod {
+	return func(q *queries.Query) {
+		queries.SetForceIndex(q, index)
+	}
+}
+
+
 // Limit the number of returned rows
 func Limit(limit int) QueryMod {
 	return func(q *queries.Query) {

queries/query.go

@@ -30,6 +30,7 @@ type Query struct {
 	selectCols []string
 	count      bool
 	from       []string
+	forceindex string
 	joins      []join
 	where      []where
 	in         []in
@@ -263,6 +264,11 @@ func SetLastWhereAsOr(q *Query) {
 	q.where[len(q.where)-1].orSeparator = true
 }
 
+// SetForceIndex sets the index to be used by the query
+func SetForceIndex(q *Query, index string){
+	q.forceindex = index
+}
+
 // SetLastInAsOr sets the or separator for the tail "IN" in the slice
 func SetLastInAsOr(q *Query) {
 	if len(q.in) == 0 {

queries/query_builders.go

@@ -76,8 +76,14 @@ func buildSelectQuery(q *Query) (*bytes.Buffer, []interface{}) {
 		buf.WriteByte(')')
 	}
 
+	if len(q.forceindex) > 0 {
+		fmt.Fprintf(buf, " FROM %s FORCE INDEX (%s)", strings.Join(strmangle.IdentQuoteSlice(q.dialect.LQ, q.dialect.RQ, q.from), ", "),q.forceindex)
+
+	}else{
 		fmt.Fprintf(buf, " FROM %s", strings.Join(strmangle.IdentQuoteSlice(q.dialect.LQ, q.dialect.RQ, q.from), ", "))
 
+	}
+
 	if len(q.joins) > 0 {
 		argsLen := len(args)
 		joinBuf := strmangle.GetBuffer()