Change one() to return Option<Model>

examples/sqlx-mysql/src/operation.rs

@@ -30,7 +30,7 @@ pub async fn insert_and_update(db: &Database) -> Result<(), ExecErr> {
     println!();
     println!("Pear: {:?}\n", pear);
 
-    let mut pear: fruit::ActiveModel = pear.into();
+    let mut pear: fruit::ActiveModel = pear.unwrap().into();
     pear.name = Val::set("Sweet pear".to_owned());
 
     let res = fruit::Entity::update(pear).exec(db).await?;

examples/sqlx-mysql/src/select.rs

@@ -70,7 +70,8 @@ async fn find_together(db: &Database) -> Result<(), QueryErr> {
 async fn find_one(db: &Database) -> Result<(), QueryErr> {
     print!("find one by primary key: ");
 
-    let cheese = cake::Entity::find_by(1).one(db).await?;
+    let cheese: Option<cake::Model> = cake::Entity::find_by(1).one(db).await?;
+    let cheese = cheese.unwrap();
 
     println!();
     println!("{:?}", cheese);
@@ -142,23 +143,27 @@ async fn find_many_to_many(db: &Database) -> Result<(), QueryErr> {
 
     let cheese = cake::Entity::find_by(1).one(db).await?;
 
+    if let Some(cheese) = cheese {
         let fillings: Vec<filling::Model> = cheese.find_filling().all(db).await?;
 
         println!();
         for ff in fillings.iter() {
             println!("{:?}\n", ff);
         }
+    }
 
     print!("find cakes for lemon: ");
 
     let lemon = filling::Entity::find_by(2).one(db).await?;
 
+    if let Some(lemon) = lemon {
         let cakes: Vec<cake::Model> = lemon.find_cake().all(db).await?;
 
         println!();
         for cc in cakes.iter() {
             println!("{:?}\n", cc);
         }
+    }
 
     Ok(())
 }

src/connector/mod.rs

@@ -23,7 +23,7 @@ pub trait Connector {
 pub trait Connection {
     async fn execute(&self, stmt: Statement) -> Result<ExecResult, ExecErr>;
 
-    async fn query_one(&self, stmt: Statement) -> Result<QueryResult, QueryErr>;
+    async fn query_one(&self, stmt: Statement) -> Result<Option<QueryResult>, QueryErr>;
 
     async fn query_all(&self, stmt: Statement) -> Result<Vec<QueryResult>, QueryErr>;
 }

src/connector/select.rs

@@ -84,7 +84,7 @@ where
         }
     }
 
-    pub async fn one(self, db: &Database) -> Result<E::Model, QueryErr> {
+    pub async fn one(self, db: &Database) -> Result<Option<E::Model>, QueryErr> {
         self.into_model::<E::Model>().one(db).await
     }
 
@@ -117,7 +117,7 @@ where
         }
     }
 
-    pub async fn one(self, db: &Database) -> Result<(E::Model, F::Model), QueryErr> {
+    pub async fn one(self, db: &Database) -> Result<Option<(E::Model, F::Model)>, QueryErr> {
         self.into_model::<E::Model, F::Model>().one(db).await
     }
 
@@ -137,11 +137,14 @@ where
         self.query.build(builder).into()
     }
 
-    pub async fn one(mut self, db: &Database) -> Result<S::Item, QueryErr> {
+    pub async fn one(mut self, db: &Database) -> Result<Option<S::Item>, QueryErr> {
         let builder = db.get_query_builder_backend();
         self.query.limit(1);
         let row = db.get_connection().query_one(self.build(builder)).await?;
-        Ok(S::from_raw_query_result(row)?)
+        match row {
+            Some(row) => Ok(Some(S::from_raw_query_result(row)?)),
+            None => Ok(None),
+        }
     }
 
     pub async fn all(self, db: &Database) -> Result<Vec<S::Item>, QueryErr> {

src/driver/sqlx_mysql.rs

@@ -46,17 +46,20 @@ impl Connection for &SqlxMySqlPoolConnection {
         Err(ExecErr)
     }
 
-    async fn query_one(&self, stmt: Statement) -> Result<QueryResult, QueryErr> {
+    async fn query_one(&self, stmt: Statement) -> Result<Option<QueryResult>, QueryErr> {
         debug_print!("{}", stmt);
 
         let query = sqlx_query(&stmt);
         if let Ok(conn) = &mut self.pool.acquire().await {
             if let Ok(row) = query.fetch_one(conn).await {
-                return Ok(row.into());
-            }
+                Ok(Some(row.into()))
+            } else {
+                Ok(None)
             }
+        } else {
             Err(QueryErr)
         }
+    }
 
     async fn query_all(&self, stmt: Statement) -> Result<Vec<QueryResult>, QueryErr> {
         debug_print!("{}", stmt);

src/entity/active_model.rs

@@ -222,8 +222,11 @@ where
     if res.last_insert_id != 0 {
         let find = E::find_by(res.last_insert_id).one(db);
         let res = find.await;
-        let model: E::Model = res.map_err(|_| ExecErr)?;
-        Ok(model.into())
+        let model: Option<E::Model> = res.map_err(|_| ExecErr)?;
+        match model {
+            Some(model) => Ok(model.into()),
+            None => Err(ExecErr),
+        }
     } else {
         Ok(A::default())
     }