Fix using pointer value as foreign key

association_test.go

@@ -600,7 +600,9 @@ func TestRelated(t *testing.T) {
 		Company:         Company{Name: "company1"},
 	}
 
-	DB.Save(&user)
+	if err := DB.Save(&user).Error; err != nil {
+		t.Errorf("No error should happen when saving user")
+	}
 
 	if user.CreditCard.ID == 0 {
 		t.Errorf("After user save, credit card should have id")

field.go

@@ -13,7 +13,7 @@ type Field struct {
 	Field   reflect.Value
 }
 
-func (field *Field) Set(value interface{}) error {
+func (field *Field) Set(value interface{}) (err error) {
 	if !field.Field.IsValid() {
 		return errors.New("field value not valid")
 	}
@@ -27,15 +27,25 @@ func (field *Field) Set(value interface{}) error {
 		reflectValue = reflect.ValueOf(value)
 	}
 
+	fieldValue := field.Field
 	if reflectValue.IsValid() {
-		if reflectValue.Type().ConvertibleTo(field.Field.Type()) {
-			field.Field.Set(reflectValue.Convert(field.Field.Type()))
-		} else if scanner, ok := field.Field.Addr().Interface().(sql.Scanner); ok {
-			if err := scanner.Scan(reflectValue.Interface()); err != nil {
-				return err
-			}
+		if reflectValue.Type().ConvertibleTo(fieldValue.Type()) {
+			fieldValue.Set(reflectValue.Convert(fieldValue.Type()))
 		} else {
-			return fmt.Errorf("could not convert argument of field %s from %s to %s", field.Name, reflectValue.Type(), field.Field.Type())
+			if fieldValue.Kind() == reflect.Ptr {
+				if fieldValue.IsNil() {
+					fieldValue.Set(reflect.New(field.Struct.Type.Elem()))
+				}
+				fieldValue = fieldValue.Elem()
+			}
+
+			if reflectValue.Type().ConvertibleTo(fieldValue.Type()) {
+				fieldValue.Set(reflectValue.Convert(fieldValue.Type()))
+			} else if scanner, ok := fieldValue.Addr().Interface().(sql.Scanner); ok {
+				err = scanner.Scan(reflectValue.Interface())
+			} else {
+				err = fmt.Errorf("could not convert argument of field %s from %s to %s", field.Name, reflectValue.Type(), fieldValue.Type())
+			}
 		}
 	} else {
 		field.Field.Set(reflect.Zero(field.Field.Type()))

preload.go

@@ -27,7 +27,7 @@ func getRealValue(value reflect.Value, columns []string) (results []interface{})
 }
 
 func equalAsString(a interface{}, b interface{}) bool {
-	return fmt.Sprintf("%v", a) == fmt.Sprintf("%v", b)
+	return toString(a) == toString(b)
 }
 
 func Preload(scope *Scope) {

query_test.go

@@ -207,11 +207,11 @@ func TestSearchWithStruct(t *testing.T) {
 }
 
 func TestSearchWithMap(t *testing.T) {
-	productID := 1
+	companyID := 1
 	user1 := User{Name: "MapSearchUser1", Age: 1, Birthday: now.MustParse("2000-1-1")}
 	user2 := User{Name: "MapSearchUser2", Age: 10, Birthday: now.MustParse("2010-1-1")}
 	user3 := User{Name: "MapSearchUser3", Age: 20, Birthday: now.MustParse("2020-1-1")}
-	user4 := User{Name: "MapSearchUser4", Age: 30, Birthday: now.MustParse("2020-1-1"), ProductID: &productID}
+	user4 := User{Name: "MapSearchUser4", Age: 30, Birthday: now.MustParse("2020-1-1"), CompanyID: &companyID}
 	DB.Save(&user1).Save(&user2).Save(&user3).Save(&user4)
 
 	var user User
@@ -237,17 +237,17 @@ func TestSearchWithMap(t *testing.T) {
 		t.Errorf("Search all records with inline map")
 	}
 
-	DB.Find(&users, map[string]interface{}{"name": user4.Name, "product_id": nil})
+	DB.Find(&users, map[string]interface{}{"name": user4.Name, "company_id": nil})
 	if len(users) != 0 {
 		t.Errorf("Search all records with inline map containing null value finding 0 records")
 	}
 
-	DB.Find(&users, map[string]interface{}{"name": user1.Name, "product_id": nil})
+	DB.Find(&users, map[string]interface{}{"name": user1.Name, "company_id": nil})
 	if len(users) != 1 {
 		t.Errorf("Search all records with inline map containing null value finding 1 record")
 	}
 
-	DB.Find(&users, map[string]interface{}{"name": user4.Name, "product_id": productID})
+	DB.Find(&users, map[string]interface{}{"name": user4.Name, "company_id": companyID})
 	if len(users) != 1 {
 		t.Errorf("Search all records with inline multiple value map")
 	}
@@ -396,8 +396,7 @@ func TestNot(t *testing.T) {
 	DB.Create(getPreparedUser("user3", "not"))
 
 	user4 := getPreparedUser("user4", "not")
-	productID := 1
-	user4.ProductID = &productID
+	user4.Company = Company{}
 	DB.Create(user4)
 
 	DB := DB.Where("role = ?", "not")
@@ -445,9 +444,9 @@ func TestNot(t *testing.T) {
 		t.Errorf("Should find all users's name not equal 3")
 	}
 
-	DB.Not(map[string]interface{}{"name": "user3", "product_id": nil}).Find(&users7)
-	if len(users7) != 1 {
-		t.Errorf("Should find all user's name not equal to 3 who do not have product ids")
+	DB.Not(map[string]interface{}{"name": "user3", "company_id": nil}).Find(&users7)
+	if len(users1)-len(users7) != 2 { // not user3 or user4
+		t.Errorf("Should find all user's name not equal to 3 who do not have company id")
 	}
 
 	DB.Not("name", []string{"user3"}).Find(&users8)

structs_test.go

@@ -28,7 +28,7 @@ type User struct {
 	CreditCard        CreditCard
 	Latitude          float64
 	Languages         []Language `gorm:"many2many:user_languages;"`
-	CompanyID         int64
+	CompanyID         *int
 	Company           Company
 	Role
 	PasswordHash      []byte

utils_private.go

@@ -82,9 +82,10 @@ func toString(str interface{}) string {
 		return strings.Join(results, "_")
 	} else if bytes, ok := str.([]byte); ok {
 		return string(bytes)
-	} else {
-		return fmt.Sprintf("%v", str)
+	} else if reflectValue := reflect.Indirect(reflect.ValueOf(str)); reflectValue.IsValid() {
+		return fmt.Sprintf("%v", reflectValue.Interface())
 	}
+	return ""
 }
 
 func strInSlice(a string, list []string) bool {