feat: add WhereNull method

contracts/database/orm/orm.go

@@ -133,6 +133,8 @@ type Query interface {
 	WhereIn(column string, values []any) Query
 	// WhereNotIn adds a "where column not in" clause to the query.
 	WhereNotIn(column string, values []any) Query
+	// WhereNull adds a "where column is null" clause to the query.
+	WhereNull(column string) Query
 	// WithoutEvents disables event firing for the query.
 	WithoutEvents() Query
 	// WithTrashed allows soft deleted models to be included in the results.

database/gorm/query.go

@@ -684,6 +684,10 @@ func (r *QueryImpl) OrWhereNotIn(column string, values []any) ormcontract.Query
 	return r.OrWhere(fmt.Sprintf("%s NOT IN ?", column), values)
 }
 
+func (r *QueryImpl) WhereNull(column string) ormcontract.Query {
+	return r.Where(fmt.Sprintf("%s IS NULL", column))
+}
+
 func (r *QueryImpl) WithoutEvents() ormcontract.Query {
 	return NewQueryImplByInstance(r.instance, &QueryImpl{
 		config:        r.config,

database/gorm/query_test.go

@@ -2813,6 +2813,20 @@ func (s *QueryTestSuite) TestOrWhereNotIn() {
 	}
 }
 
+func (s *QueryTestSuite) TestWhereNull() {
+	for driver, query := range s.queries {
+		s.Run(driver.String(), func() {
+			user := User{Name: "where_null_user", Avatar: "where_null_avatar"}
+			s.Nil(query.Create(&user))
+			s.True(user.ID > 0)
+
+			var users []User
+			s.Nil(query.WhereNull("name").Find(&users))
+			s.True(len(users) == 0)
+		})
+	}
+}
+
 func (s *QueryTestSuite) TestWithoutEvents() {
 	for _, query := range s.queries {
 		tests := []struct {