Support SubQuery for Generics

generics.go

@@ -127,6 +127,11 @@ type chainG[T any] struct {
 	execG[T]
 }
 
+func (c chainG[T]) getInstance() *DB {
+	var r T
+	return c.g.apply(context.Background()).Model(r).getInstance()
+}
+
 func (c chainG[T]) with(op op) chainG[T] {
 	return chainG[T]{
 		execG: execG[T]{g: &g[T]{

statement.go

@@ -205,19 +205,20 @@ func (stmt *Statement) AddVar(writer clause.Writer, vars ...interface{}) {
 			} else {
 				writer.WriteString("(NULL)")
 			}
-		case *DB:
+		case interface{ getInstance() *DB }:
-			subdb := v.Session(&Session{Logger: logger.Discard, DryRun: true}).getInstance()
+			cv := v.getInstance()
-			if v.Statement.SQL.Len() > 0 {
+			subdb := cv.Session(&Session{Logger: logger.Discard, DryRun: true}).getInstance()
+			if cv.Statement.SQL.Len() > 0 {
 				var (
 					vars = subdb.Statement.Vars
-					sql  = v.Statement.SQL.String()
+					sql  = cv.Statement.SQL.String()
 				)
 
 				subdb.Statement.Vars = make([]interface{}, 0, len(vars))
 				for _, vv := range vars {
 					subdb.Statement.Vars = append(subdb.Statement.Vars, vv)
 					bindvar := strings.Builder{}
-					v.Dialector.BindVarTo(&bindvar, subdb.Statement, vv)
+					cv.Dialector.BindVarTo(&bindvar, subdb.Statement, vv)
 					sql = strings.Replace(sql, bindvar.String(), "?", 1)
 				}
 

tests/generics_test.go

@@ -366,3 +366,35 @@ func TestGenericsGroupHaving(t *testing.T) {
 		t.Errorf("expected group name 'GenericsGroupHavingMulti', got '%s'", grouped[0].Name)
 	}
 }
+
+func TestGenericsSubQuery(t *testing.T) {
+	ctx := context.Background()
+	users := []User{
+		{Name: "GenericsSubquery_1", Age: 10},
+		{Name: "GenericsSubquery_2", Age: 20},
+		{Name: "GenericsSubquery_3", Age: 30},
+		{Name: "GenericsSubquery_4", Age: 40},
+	}
+
+	if err := gorm.G[User](DB).CreateInBatches(ctx, &users, len(users)); err != nil {
+		t.Fatalf("CreateInBatches failed: %v", err)
+	}
+
+	results, err := gorm.G[User](DB).Where("name IN (?)", gorm.G[User](DB).Select("name").Where("name LIKE ?", "GenericsSubquery%")).Find(ctx)
+	if err != nil {
+		t.Fatalf("got error: %v", err)
+	}
+
+	if len(results) != 4 {
+		t.Errorf("Four users should be found, instead found %d", len(results))
+	}
+
+	results, err = gorm.G[User](DB).Where("name IN (?)", gorm.G[User](DB).Select("name").Where("name IN ?", []string{"GenericsSubquery_1", "GenericsSubquery_2"}).Or("name = ?", "GenericsSubquery_3")).Find(ctx)
+	if err != nil {
+		t.Fatalf("got error: %v", err)
+	}
+
+	if len(results) != 3 {
+		t.Errorf("Three users should be found, instead found %d", len(results))
+	}
+}

tests/go.mod

@@ -1,6 +1,6 @@
 module gorm.io/gorm/tests
 
-go 1.18.0
+go 1.23.0
 
 require (
 	github.com/google/uuid v1.6.0