Don't set foreign key to be null when delete with a wrong relation

association.go

@@ -208,7 +208,14 @@ func (association *Association) Delete(values ...interface{}) *Association {
 			)
 
 			// set foreign key to be null
-			association.setErr(newDB.Model(scope.Value).UpdateColumn(foreignKeyMap).Error)
+			modelValue := reflect.New(scope.GetModelStruct().ModelType).Interface()
+			if results := newDB.Model(modelValue).UpdateColumn(foreignKeyMap); results.Error == nil {
+				if results.RowsAffected > 0 {
+					scope.updatedAttrsWithValues(foreignKeyMap, false)
+				}
+			} else {
+				association.setErr(results.Error)
+			}
 		} else if relationship.Kind == "has_one" || relationship.Kind == "has_many" {
 			// find all relations
 			primaryKeys := association.getPrimaryKeys(relationship.AssociationForeignFieldNames, scope.Value)

association_test.go

@@ -46,6 +46,14 @@ func TestBelongsTo(t *testing.T) {
 		t.Errorf("Query belongs to relations with Related")
 	}
 
+	if DB.Model(&post).Association("Category").Count() == 1 {
+		t.Errorf("Post's category count should be 1")
+	}
+
+	if DB.Model(&post).Association("MainCategory").Count() == 1 {
+		t.Errorf("Post's main category count should be 1")
+	}
+
 	// Append
 	var category2 = Category{
 		Name: "Category 2",
@@ -63,6 +71,10 @@ func TestBelongsTo(t *testing.T) {
 		t.Errorf("Category should be updated with Append")
 	}
 
+	if DB.Model(&post).Association("Category").Count() == 1 {
+		t.Errorf("Post's category count should be 1")
+	}
+
 	// Replace
 	var category3 = Category{
 		Name: "Category 3",
@@ -79,9 +91,14 @@ func TestBelongsTo(t *testing.T) {
 		t.Errorf("Category should be updated with Replace")
 	}
 
+	if DB.Model(&post).Association("Category").Count() == 1 {
+		t.Errorf("Post's category count should be 1")
+	}
+
 	// Delete
 	DB.Model(&post).Association("Category").Delete(&category2)
-	DB.First(&post, post.Id)
+	fmt.Println(post)
+	fmt.Println(post.Category)
 	if DB.Model(&post).Related(&Category{}).RecordNotFound() {
 		t.Errorf("Should not delete any category when Delete a unrelated Category")
 	}
@@ -94,6 +111,10 @@ func TestBelongsTo(t *testing.T) {
 		t.Errorf("Category should be deleted with Delete")
 	}
 
+	if DB.Model(&post).Association("Category").Count() == 0 {
+		t.Errorf("Post's category count should be 0 after Delete")
+	}
+
 	// Clear
 	DB.Model(&post).Association("Category").Append(&Category{
 		Name: "Category 2",
@@ -108,6 +129,10 @@ func TestBelongsTo(t *testing.T) {
 	if !DB.Model(&post).Related(&Category{}).RecordNotFound() {
 		t.Errorf("Should not find any category after Clear")
 	}
+
+	if DB.Model(&post).Association("Category").Count() == 0 {
+		t.Errorf("Post's category count should be 0 after Clear")
+	}
 }
 
 func TestHasOne(t *testing.T) {