Refactor JoinTableHandler

join_table_handler.go

@@ -1,14 +1,16 @@
 package gorm
 
 import (
+	"errors"
 	"fmt"
 	"reflect"
 	"strings"
 )
 
 type JoinTableHandlerInterface interface {
+	Setup(relationship *Relationship, tableName string, source reflect.Type, destination reflect.Type)
 	Table(db *DB) string
-	Add(db *DB, source1 interface{}, source2 interface{}) error
+	Add(db *DB, source interface{}, destination interface{}) error
 	Delete(db *DB, sources ...interface{}) error
 	JoinWith(db *DB, source interface{}) *DB
 }
@@ -29,22 +31,24 @@ type JoinTableHandler struct {
 	Destination JoinTableSource `sql:"-"`
 }
 
-func updateJoinTableHandler(relationship *Relationship) {
-	handler := relationship.JoinTableHandler.(*JoinTableHandler)
+func (s *JoinTableHandler) Setup(relationship *Relationship, tableName string, source reflect.Type, destination reflect.Type) {
+	s.TableName = tableName
 
-	destinationScope := &Scope{Value: reflect.New(handler.Destination.ModelType).Interface()}
-	for _, primaryField := range destinationScope.GetModelStruct().PrimaryFields {
-		db := relationship.AssociationForeignDBName
-		handler.Destination.ForeignKeys = append(handler.Destination.ForeignKeys, JoinTableForeignKey{
+	s.Source = JoinTableSource{ModelType: source}
+	sourceScope := &Scope{Value: reflect.New(source).Interface()}
+	for _, primaryField := range sourceScope.GetModelStruct().PrimaryFields {
+		db := relationship.ForeignDBName
+		s.Source.ForeignKeys = append(s.Source.ForeignKeys, JoinTableForeignKey{
 			DBName:            db,
 			AssociationDBName: primaryField.DBName,
 		})
 	}
 
-	sourceScope := &Scope{Value: reflect.New(handler.Source.ModelType).Interface()}
-	for _, primaryField := range sourceScope.GetModelStruct().PrimaryFields {
-		db := relationship.ForeignDBName
-		handler.Source.ForeignKeys = append(handler.Source.ForeignKeys, JoinTableForeignKey{
+	s.Destination = JoinTableSource{ModelType: destination}
+	destinationScope := &Scope{Value: reflect.New(destination).Interface()}
+	for _, primaryField := range destinationScope.GetModelStruct().PrimaryFields {
+		db := relationship.AssociationForeignDBName
+		s.Destination.ForeignKeys = append(s.Destination.ForeignKeys, JoinTableForeignKey{
 			DBName:            db,
 			AssociationDBName: primaryField.DBName,
 		})
@@ -136,18 +140,10 @@ func (s JoinTableHandler) JoinWith(db *DB, source interface{}) *DB {
 			queryConditions = append(queryConditions, fmt.Sprintf("%v.%v = ?", quotedTable, scope.Quote(foreignKey.DBName)))
 			values = append(values, scope.Fields()[foreignKey.AssociationDBName].Field.Interface())
 		}
-	} else if s.Destination.ModelType == modelType {
-		for _, foreignKey := range s.Source.ForeignKeys {
-			sourceTableName := scope.New(reflect.New(s.Source.ModelType).Interface()).QuotedTableName()
-			joinConditions = append(joinConditions, fmt.Sprintf("%v.%v = %v.%v", quotedTable, scope.Quote(foreignKey.DBName), sourceTableName, scope.Quote(foreignKey.AssociationDBName)))
-		}
-
-		for _, foreignKey := range s.Destination.ForeignKeys {
-			queryConditions = append(queryConditions, fmt.Sprintf("%v.%v = ?", quotedTable, scope.Quote(foreignKey.DBName)))
-			values = append(values, scope.Fields()[foreignKey.AssociationDBName].Field.Interface())
-		}
-	}
-
 		return db.Joins(fmt.Sprintf("INNER JOIN %v ON %v", quotedTable, strings.Join(joinConditions, " AND "))).
 			Where(strings.Join(queryConditions, " AND "), values...)
+	} else {
+		db.Error = errors.New("wrong source type for join table handler")
+		return db
+	}
 }

join_table_test.go

@@ -15,16 +15,13 @@ type Person struct {
 }
 
 type PersonAddress struct {
+	gorm.JoinTableHandler
 	PersonID  int
 	AddressID int
 	DeletedAt time.Time
 	CreatedAt time.Time
 }
 
-func (*PersonAddress) Table(db *gorm.DB) string {
-	return "person_addresses"
-}
-
 func (*PersonAddress) Add(db *gorm.DB, foreignValue interface{}, associationValue interface{}) error {
 	return db.Where(map[string]interface{}{
 		"person_id":  db.NewScope(foreignValue).PrimaryKeyValue(),
@@ -32,7 +29,7 @@ func (*PersonAddress) Add(db *gorm.DB, foreignValue interface{}, associationValu
 	}).Assign(map[string]interface{}{
 		"person_id":  foreignValue,
 		"address_id": associationValue,
-		"DeletedAt":  gorm.Expr("NULL"),
+		"deleted_at": gorm.Expr("NULL"),
 	}).FirstOrCreate(&PersonAddress{}).Error
 }
 

main.go

@@ -473,8 +473,13 @@ func (s *DB) Get(name string) (value interface{}, ok bool) {
 func (s *DB) SetJoinTableHandler(source interface{}, column string, handler JoinTableHandlerInterface) {
 	for _, field := range s.NewScope(source).GetModelStruct().StructFields {
 		if field.Name == column || field.DBName == column {
+			if many2many := parseTagSetting(field.Tag.Get("gorm"))["MANY2MANY"]; many2many != "" {
+				source := (&Scope{Value: source}).GetModelStruct().ModelType
+				destination := (&Scope{Value: reflect.New(field.Struct.Type).Interface()}).GetModelStruct().ModelType
+				handler.Setup(field.Relationship, many2many, source, destination)
 				field.Relationship.JoinTableHandler = handler
 				s.Table(handler.Table(s)).AutoMigrate(handler)
 			}
 		}
+	}
 }

model_struct.go

@@ -215,13 +215,10 @@ func (scope *Scope) GetModelStruct() *ModelStruct {
 								relationship.ForeignDBName = ToDBName(foreignKey)
 								relationship.AssociationForeignFieldName = associationForeignKey
 								relationship.AssociationForeignDBName = ToDBName(associationForeignKey)
-								relationship.JoinTableHandler = &JoinTableHandler{
-									TableName:   many2many,
-									Source:      JoinTableSource{ModelType: scopeType},
-									Destination: JoinTableSource{ModelType: elemType},
-								}
-								updateJoinTableHandler(relationship)
 
+								joinTableHandler := JoinTableHandler{}
+								joinTableHandler.Setup(relationship, many2many, scopeType, elemType)
+								relationship.JoinTableHandler = &joinTableHandler
 								field.Relationship = relationship
 							} else {
 								relationship.Kind = "has_many"