From 5daa9abd38fde08debde86cadada198e935b34cb Mon Sep 17 00:00:00 2001
From: Chris Tsang <tyt2y7@gmail.com>
Date: Sat, 23 Oct 2021 15:41:16 +0800
Subject: [PATCH] #267 Added `is_null` and `is_not_null`

---
 src/entity/column.rs | 13 ++++++++-----
 src/query/helper.rs  | 12 ++++++++++++
 2 files changed, 20 insertions(+), 5 deletions(-)

diff --git a/src/entity/column.rs b/src/entity/column.rs
index b7ce2820..423e3e3b 100644
--- a/src/entity/column.rs
+++ b/src/entity/column.rs
@@ -47,8 +47,9 @@ macro_rules! bind_oper {
     };
 }
 
-macro_rules! bind_agg_func {
+macro_rules! bind_func_no_params {
     ( $func: ident ) => {
+        /// See also SeaQuery's method with same name.
         fn $func(&self) -> SimpleExpr {
             Expr::tbl(self.entity_name(), *self).$func()
         }
@@ -213,10 +214,12 @@ pub trait ColumnTrait: IdenStatic + Iterable + FromStr {
         Expr::tbl(self.entity_name(), *self).like(&pattern)
     }
 
-    bind_agg_func!(max);
-    bind_agg_func!(min);
-    bind_agg_func!(sum);
-    bind_agg_func!(count);
+    bind_func_no_params!(max);
+    bind_func_no_params!(min);
+    bind_func_no_params!(sum);
+    bind_func_no_params!(count);
+    bind_func_no_params!(is_null);
+    bind_func_no_params!(is_not_null);
 
     fn if_null<V>(&self, v: V) -> SimpleExpr
     where
diff --git a/src/query/helper.rs b/src/query/helper.rs
index 7efe0ca1..bf762fc9 100644
--- a/src/query/helper.rs
+++ b/src/query/helper.rs
@@ -340,6 +340,18 @@ pub trait QueryFilter: Sized {
     ///     r#"SELECT "cake"."id", "cake"."name" FROM "cake" WHERE (NOT (1 = 1 AND 2 = 2)) AND (3 = 3 OR 4 = 4)"#
     /// );
     /// ```
+    /// Use a sea_query expression
+    /// ```
+    /// use sea_orm::{entity::*, query::*, sea_query::Expr, tests_cfg::fruit, DbBackend};
+    ///
+    /// assert_eq!(
+    ///     fruit::Entity::find()
+    ///         .filter(Expr::col(fruit::Column::CakeId).is_null())
+    ///         .build(DbBackend::MySql)
+    ///         .to_string(),
+    ///     "SELECT `fruit`.`id`, `fruit`.`name`, `fruit`.`cake_id` FROM `fruit` WHERE `cake_id` IS NULL"
+    /// );
+    /// ```
     fn filter<F>(mut self, filter: F) -> Self
     where
         F: IntoCondition,