From 9c2c0d24140c4018af950c732ece69dd3cf2a870 Mon Sep 17 00:00:00 2001
From: Jinlong Chen <jinlongchen@live.com>
Date: Tue, 2 May 2023 09:34:28 +0800
Subject: [PATCH] feat: add handling for the interface field, when an Interface
 field is an object that has already been instantiated, use the type of the
 instantiated object itself instead of interface{}.

---
 schema/field.go  | 11 +++++++++++
 schema/schema.go |  5 ++++-
 2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/schema/field.go b/schema/field.go
index b5103d53..8292c965 100644
--- a/schema/field.go
+++ b/schema/field.go
@@ -12,6 +12,7 @@ import (
 	"time"
 
 	"github.com/jinzhu/now"
+
 	"gorm.io/gorm/clause"
 	"gorm.io/gorm/utils"
 )
@@ -122,6 +123,16 @@ func (schema *Schema) ParseField(fieldStruct reflect.StructField) *Field {
 		AutoIncrementIncrement: 1,
 	}
 
+	if field.IndirectFieldType.Kind() == reflect.Interface {
+		f := schema.ModelValue.FieldByName(fieldStruct.Name)
+		if f.IsValid() {
+			e := f.Elem()
+			if e.IsValid() {
+				field.IndirectFieldType = e.Type()
+			}
+		}
+	}
+
 	for field.IndirectFieldType.Kind() == reflect.Ptr {
 		field.IndirectFieldType = field.IndirectFieldType.Elem()
 	}
diff --git a/schema/schema.go b/schema/schema.go
index e13a5ed1..a9c53b70 100644
--- a/schema/schema.go
+++ b/schema/schema.go
@@ -18,6 +18,7 @@ var ErrUnsupportedDataType = errors.New("unsupported data type")
 
 type Schema struct {
 	Name                      string
+	ModelValue                reflect.Value
 	ModelType                 reflect.Type
 	Table                     string
 	PrioritizedPrimaryField   *Field
@@ -113,6 +114,8 @@ func ParseWithSpecialTableName(dest interface{}, cacheStore *sync.Map, namer Nam
 	if value.Kind() == reflect.Ptr && value.IsNil() {
 		value = reflect.New(value.Type().Elem())
 	}
+
+	modelValue := reflect.Indirect(value)
 	modelType := reflect.Indirect(value).Type()
 
 	if modelType.Kind() == reflect.Interface {
@@ -147,7 +150,6 @@ func ParseWithSpecialTableName(dest interface{}, cacheStore *sync.Map, namer Nam
 		return s, s.err
 	}
 
-	modelValue := reflect.New(modelType)
 	tableName := namer.TableName(modelType.Name())
 	if tabler, ok := modelValue.Interface().(Tabler); ok {
 		tableName = tabler.TableName()
@@ -164,6 +166,7 @@ func ParseWithSpecialTableName(dest interface{}, cacheStore *sync.Map, namer Nam
 
 	schema := &Schema{
 		Name:             modelType.Name(),
+		ModelValue:       modelValue,
 		ModelType:        modelType,
 		Table:            tableName,
 		FieldsByName:     map[string]*Field{},