diff --git a/examples/basic/src/example_cake.rs b/examples/basic/src/example_cake.rs
index b3364df8..6d877ac6 100644
--- a/examples/basic/src/example_cake.rs
+++ b/examples/basic/src/example_cake.rs
@@ -37,4 +37,12 @@ impl Related<super::filling::Entity> for Entity {
     }
 }
 
-impl ActiveModelBehavior for ActiveModel {}
+#[async_trait::async_trait]
+impl ActiveModelBehavior for ActiveModel {
+    async fn before_save<C>(self, _db: &C, _insert: bool) -> Result<Self, DbErr>
+    where
+        C: ConnectionTrait,
+    {
+        Ok(self)
+    }
+}
diff --git a/src/entity/prelude.rs b/src/entity/prelude.rs
index 47b22bcc..2e69f9c0 100644
--- a/src/entity/prelude.rs
+++ b/src/entity/prelude.rs
@@ -1,9 +1,9 @@
 pub use crate::{
     error::*, ActiveEnum, ActiveModelBehavior, ActiveModelTrait, ColumnDef, ColumnTrait,
-    ColumnType, ColumnTypeTrait, CursorTrait, DatabaseConnection, DbConn, EntityName, EntityTrait,
-    EnumIter, ForeignKeyAction, Iden, IdenStatic, Linked, LoaderTrait, ModelTrait, PaginatorTrait,
-    PrimaryKeyToColumn, PrimaryKeyTrait, QueryFilter, QueryResult, Related, RelationDef,
-    RelationTrait, Select, Value,
+    ColumnType, ColumnTypeTrait, ConnectionTrait, CursorTrait, DatabaseConnection, DbConn,
+    EntityName, EntityTrait, EnumIter, ForeignKeyAction, Iden, IdenStatic, Linked, LoaderTrait,
+    ModelTrait, PaginatorTrait, PrimaryKeyToColumn, PrimaryKeyTrait, QueryFilter, QueryResult,
+    Related, RelationDef, RelationTrait, Select, Value,
 };
 
 #[cfg(feature = "macros")]
@@ -13,6 +13,8 @@ pub use crate::{
     DerivePrimaryKey, DeriveRelation, FromJsonQueryResult,
 };
 
+pub use async_trait;
+
 #[cfg(feature = "with-json")]
 pub use serde_json::Value as Json;