fix issue in converting value to nil when calling IsNil return ture for gdb.Core (#2720)

contrib/drivers/mysql/mysql_basic_test.go

@@ -11,7 +11,9 @@ import (
 	"testing"
 
 	"github.com/go-sql-driver/mysql"
+	"github.com/gogf/gf/v2/container/gvar"
 	"github.com/gogf/gf/v2/database/gdb"
+	"github.com/gogf/gf/v2/encoding/gjson"
 	"github.com/gogf/gf/v2/test/gtest"
 )
 
@@ -42,6 +44,47 @@ func Test_Func_ConvertDataForRecord(t *testing.T) {
 		t.Assert(len(m), 1)
 		t.Assert(m["reset_password_token_at"], nil)
 	})
+
+	type TestNil struct {
+		JsonEmptyString *gjson.Json `orm:"json_empty_string"`
+		JsonNil         *gjson.Json `orm:"json_nil"`
+		JsonNull        *gjson.Json `orm:"json_null"`
+		VarEmptyString  *gvar.Var   `orm:"var_empty_string"`
+		VarNil          *gvar.Var   `orm:"var_nil"`
+	}
+	gtest.C(t, func(t *gtest.T) {
+		c := &gdb.Core{}
+		m, err := c.ConvertDataForRecord(nil, TestNil{
+			JsonEmptyString: gjson.New(""),
+			JsonNil:         gjson.New(nil),
+			JsonNull:        gjson.New(struct{}{}),
+			VarEmptyString:  gvar.New(""),
+			VarNil:          gvar.New(nil),
+		})
+
+		t.AssertNil(err)
+		t.Assert(len(m), 5)
+
+		valueEmptyString, exist := m["json_empty_string"]
+		t.Assert(exist, true)
+		t.Assert(valueEmptyString, nil)
+
+		valueNil, exist := m["json_nil"]
+		t.Assert(exist, true)
+		t.Assert(valueNil, nil)
+
+		valueNull, exist := m["json_null"]
+		t.Assert(exist, true)
+		t.Assert(valueNull, "null")
+
+		valueEmptyString, exist = m["var_empty_string"]
+		t.Assert(exist, true)
+		t.Assert(valueEmptyString, "")
+
+		valueNil, exist = m["var_nil"]
+		t.Assert(exist, true)
+		t.Assert(valueNil, nil)
+	})
 }
 
 func Test_Func_FormatSqlWithArgs(t *testing.T) {

contrib/drivers/mysql/mysql_core_test.go

@@ -258,6 +258,51 @@ func Test_DB_Insert_KeyFieldNameMapping(t *testing.T) {
 	})
 }
 
+func Test_DB_Insert_NilGjson(t *testing.T) {
+	var tableName = "nil" + gtime.TimestampNanoStr()
+	_, err := db.Exec(ctx, fmt.Sprintf(`
+	CREATE TABLE IF NOT EXISTS %s (
+		id int(10) unsigned NOT NULL AUTO_INCREMENT,
+		json_empty_string json DEFAULT NULL,
+		json_nil json DEFAULT NULL,
+		json_null json DEFAULT NULL,
+		PRIMARY KEY (id)
+	) ENGINE=InnoDB DEFAULT CHARSET=utf8;
+	`, tableName))
+	if err != nil {
+		gtest.Fatal(err)
+	}
+	defer dropTable(tableName)
+
+	gtest.C(t, func(t *gtest.T) {
+		type Json struct {
+			Id              int
+			JsonEmptyString *gjson.Json
+			JsonNil         *gjson.Json
+			JsonNull        *gjson.Json
+		}
+
+		data := Json{
+			Id:              1,
+			JsonEmptyString: gjson.New(""),
+			JsonNil:         gjson.New(nil),
+			JsonNull:        gjson.New(struct{}{}),
+		}
+
+		_, err = db.Insert(ctx, tableName, data)
+		t.AssertNil(err)
+
+		one, err := db.GetOne(ctx, fmt.Sprintf("SELECT * FROM %s WHERE id=?", tableName), 1)
+		t.AssertNil(err)
+
+		t.AssertEQ(len(one), 4)
+
+		t.Assert(one["json_empty_string"], nil)
+		t.Assert(one["json_nil"], nil)
+		t.Assert(one["json_null"], "null")
+	})
+}
+
 func Test_DB_Upadte_KeyFieldNameMapping(t *testing.T) {
 	table := createInitTable()
 	defer dropTable(table)

database/gdb/gdb_core_structure.go

@@ -106,8 +106,13 @@ func (c *Core) ConvertDataForRecordValue(ctx context.Context, value interface{})
 			// Nothing to do.
 
 		default:
-			// Use string conversion in default.
+			// If `value` implements interface iNil,
-			if s, ok := value.(iString); ok {
+			// check its IsNil() function, if got ture,
+			// which will insert/update the value to database as "null".
+			if v, ok := value.(iNil); ok && v.IsNil() {
+				convertedValue = nil
+			} else if s, ok := value.(iString); ok {
+				// Use string conversion in default.
 				convertedValue = s.String()
 			} else {
 				// Convert the value to JSON.

database/gdb/gdb_func.go

@@ -44,6 +44,11 @@ type iInterfaces interface {
 	Interfaces() []interface{}
 }
 
+// iNil if the type assert api for IsNil.
+type iNil interface {
+	IsNil() bool
+}
+
 // iTableName is the interface for retrieving table name for struct.
 type iTableName interface {
 	TableName() string