Fix mock preload many2many generating empty relation rows

callback_query_preload.go

@@ -60,6 +60,7 @@ func preloadCallback(scope *Scope) {
 						currentScope.handleBelongsToPreload(field, currentPreloadConditions)
 					case "many_to_many":
 						currentScope.handleManyToManyPreload(field, currentPreloadConditions)
+
 					default:
 						scope.Err(errors.New("unsupported relation"))
 					}
@@ -264,6 +265,8 @@ func (scope *Scope) handleBelongsToPreload(field *Field, conditions []interface{
 
 // handleManyToManyPreload used to preload many to many associations
 func (scope *Scope) handleManyToManyPreload(field *Field, conditions []interface{}) {
+	// spew.Println("___ENTERING HANDLE MANY TO MANY___\r\n")
+	// spew.Printf("___POPULATING %s___:\r\n%s\r\n", field.Name, spew.Sdump(field))
 	var (
 		relation         = field.Relationship
 		joinTableHandler = relation.JoinTableHandler
@@ -303,6 +306,7 @@ func (scope *Scope) handleManyToManyPreload(field *Field, conditions []interface
 	}
 
 	rows, err := preloadDB.Rows()
+	// spew.Printf("___RETURNED ROWS___: \r\n%s\r\n", spew.Sdump(rows))
 
 	if scope.Err(err) != nil {
 		return
@@ -312,6 +316,7 @@ func (scope *Scope) handleManyToManyPreload(field *Field, conditions []interface
 	columns, _ := rows.Columns()
 	for rows.Next() {
 		var (
+			// This is a Language zero value struct
 			elem   = reflect.New(fieldType).Elem()
 			fields = scope.New(elem.Addr().Interface()).Fields()
 		)
@@ -323,6 +328,7 @@ func (scope *Scope) handleManyToManyPreload(field *Field, conditions []interface
 		}
 
 		scope.scan(rows, columns, append(fields, joinTableFields...))
+		// spew.Printf("___FIELDS___: \r\n%s\r\n", spew.Sdump(fields))
 
 		var foreignKeys = make([]interface{}, len(sourceKeys))
 		// generate hashed forkey keys in join table
@@ -351,12 +357,14 @@ func (scope *Scope) handleManyToManyPreload(field *Field, conditions []interface
 		foreignFieldNames  = []string{}
 	)
 
+	// spew.Printf("Foreign fields: %s", spew.Sdump(relation.ForeignFieldNames))
 	for _, dbName := range relation.ForeignFieldNames {
 		if field, ok := scope.FieldByName(dbName); ok {
 			foreignFieldNames = append(foreignFieldNames, field.Name)
 		}
 	}
 
+	// spew.Printf("Scope value: %s", spew.Sdump(indirectScopeValue))
 	if indirectScopeValue.Kind() == reflect.Slice {
 		for j := 0; j < indirectScopeValue.Len(); j++ {
 			object := indirect(indirectScopeValue.Index(j))
@@ -367,6 +375,9 @@ func (scope *Scope) handleManyToManyPreload(field *Field, conditions []interface
 		key := toString(getValueFromFields(indirectScopeValue, foreignFieldNames))
 		fieldsSourceMap[key] = append(fieldsSourceMap[key], indirectScopeValue.FieldByName(field.Name))
 	}
+
+	// spew.Printf("Field source map: %s", spew.Sdump(fieldsSourceMap))
+	// spew.Printf("Link hash: %s", spew.Sdump(linkHash))
 	for source, link := range linkHash {
 		for i, field := range fieldsSourceMap[source] {
 			//If not 0 this means Value is a pointer and we already added preloaded models to it

expecter_result.go

@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"reflect"
 
+	"github.com/davecgh/go-spew/spew"
 	sqlmock "gopkg.in/DATA-DOG/go-sqlmock.v1"
 )
 
@@ -46,6 +47,7 @@ func getRowForFields(fields []*Field) []driver.Value {
 			}
 
 			concreteVal := value.Interface()
+			// spew.Printf("%v: %v\r\n", field.Name, concreteVal)
 
 			if driver.IsValue(concreteVal) {
 				values = append(values, concreteVal)
@@ -68,6 +70,12 @@ func getRelationRows(rVal reflect.Value, fieldName string, relation *Relationshi
 		columns []string
 	)
 
+	// we need to check for zero values
+	if reflect.DeepEqual(rVal.Interface(), reflect.New(rVal.Type()).Elem().Interface()) {
+		spew.Printf("FOUND EMPTY INTERFACE FOR %s\r\n", fieldName)
+		return nil, false
+	}
+
 	switch relation.Kind {
 	case "has_one":
 		scope := &Scope{Value: rVal.Interface()}
@@ -94,6 +102,9 @@ func getRelationRows(rVal reflect.Value, fieldName string, relation *Relationshi
 				columns = append(columns, field.DBName)
 			}
 		}
+		spew.Printf("___GENERATING ROWS FOR %s___\r\n", fieldName)
+		spew.Printf("___COLUMNS___:\r\n%s\r\n", spew.Sdump(columns))
+		columns = append(columns, "user_id", "language_id")
 
 		rows = sqlmock.NewRows(columns)
 
@@ -102,11 +113,14 @@ func getRelationRows(rVal reflect.Value, fieldName string, relation *Relationshi
 			for i := 0; i < rVal.Len(); i++ {
 				scope := &Scope{Value: rVal.Index(i).Interface()}
 				row := getRowForFields(scope.Fields())
+				row = append(row, 1, 1)
 				rows = rows.AddRow(row...)
 			}
+
+			return rows, true
 		}
 
-		return rows, true
+		return nil, false
 	default:
 		return nil, false
 	}
@@ -163,6 +177,7 @@ func (q *SqlmockQuery) getRowsForOutType(out interface{}) []*sqlmock.Rows {
 			relationRows, hasRows := getRelationRows(rVal, name, relation)
 
 			if hasRows {
+				spew.Printf("___GENERATED ROWS FOR %s___\r\n: %s\r\n", name, spew.Sdump(relationRows))
 				rowsSet = append(rowsSet, relationRows)
 			}
 		}
@@ -181,6 +196,7 @@ func (q *SqlmockQuery) Returns(out interface{}) ExpectedQuery {
 
 	for i, query := range q.queries {
 		query.WillReturnRows(rows[i])
+		spew.Printf("___SET RETURN ROW___: %s", spew.Sdump(rows[i]))
 	}
 
 	return q

expecter_test.go

@@ -5,6 +5,7 @@ import (
 	"reflect"
 	"testing"
 
+	"github.com/davecgh/go-spew/spew"
 	"github.com/jinzhu/gorm"
 )
 
@@ -181,7 +182,7 @@ func TestMockPreloadMany2Many(t *testing.T) {
 	}
 
 	in := User{Id: 1}
-	languages := []Language{Language{Name: "ZH"}, Language{Name: "EN"}}
+	languages := []Language{Language{Name: "ZH"}}
 	out := User{Id: 1, Languages: languages}
 
 	expect.Preload("Languages").Find(&in).Returns(out)
@@ -191,7 +192,10 @@ func TestMockPreloadMany2Many(t *testing.T) {
 		t.Error(err)
 	}
 
-	// 	if !reflect.DeepEqual(in, out) {
-	// 		t.Error("In and out are not equal")
-	// 	}
+	spew.Printf("______IN______\r\n%s\r\n", spew.Sdump(in))
+	spew.Printf("______OUT______\r\n%s\r\n", spew.Sdump(out))
+
+	if !reflect.DeepEqual(in, out) {
+		t.Error("In and out are not equal")
+	}
 }