Many to many prototype

README.md

@@ -49,4 +49,4 @@ Balance between compile-time checking and compilation speed.
 
 3. Avoid 'symbol soup'
 
-Avoid function-like macros with DSL, use derive macros where appropriate. Be friendly with IDE tools.
+Avoid macros with DSL, use derive macros where appropriate. Be friendly with IDE tools.

examples/bakery.sql

@@ -8,7 +8,7 @@ CREATE TABLE `cake` (
 
 INSERT INTO `cake` (`id`, `name`) VALUES
 	(1, 'New York Cheese'),
-	(2, 'Chocolate Fudge');
+	(2, 'Chocolate Forest');
 
 DROP TABLE IF EXISTS `fruit`;
 
@@ -20,6 +20,33 @@ CREATE TABLE `fruit` (
 ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;
 
 INSERT INTO `fruit` (`id`, `name`, `cake_id`) VALUES
-	(1, 'Blueberry', 1),
-	(2, 'Rasberry', 1),
-	(3, 'Strawberry', 2);
+  (1, 'Blueberry', 1),
+  (2, 'Rasberry', 1),
+  (3, 'Strawberry', 2);
+
+DROP TABLE IF EXISTS `filling`;
+
+CREATE TABLE `filling` (
+  `id` int NOT NULL AUTO_INCREMENT,
+  `name` varchar(255) DEFAULT NULL,
+  PRIMARY KEY (`id`)
+) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;
+
+INSERT INTO `filling` (`id`, `name`) VALUES
+  (1, 'Vanilla'),
+  (2, 'Lemon'),
+  (3, 'Mango');
+
+DROP TABLE IF EXISTS `cake_filling`;
+
+CREATE TABLE `cake_filling` (
+  `cake_id` int NOT NULL,
+  `filling_id` int NOT NULL,
+  PRIMARY KEY (`cake_id`, `filling_id`)
+) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;
+
+INSERT INTO `cake_filling` (`cake_id`, `filling_id`) VALUES
+  (1, 1),
+  (1, 2),
+  (2, 2),
+  (2, 3);

src/entity/relation.rs

@@ -1,4 +1,4 @@
-use crate::{EntityTrait, Identity, IntoIdentity, Select};
+use crate::{EntityTrait, Identity, IntoIdentity, QueryHelper, Select};
 use core::marker::PhantomData;
 use sea_query::{Iden, IntoIden, JoinType};
 use std::fmt::Debug;

src/query/helper.rs

@@ -1,7 +1,7 @@
-use crate::{ColumnTrait, IntoSimpleExpr};
+use crate::{ColumnTrait, Identity, IntoSimpleExpr, RelationDef};
 
 pub use sea_query::JoinType;
-use sea_query::{Alias, Order, SelectExpr, SelectStatement, SimpleExpr};
+use sea_query::{Alias, Expr, Order, SelectExpr, SelectStatement, SimpleExpr};
 use std::rc::Rc;
 
 pub trait QueryHelper: Sized {
@@ -138,4 +138,44 @@ pub trait QueryHelper: Sized {
             .order_by_expr(col.into_simple_expr(), Order::Desc);
         self
     }
+
+    #[doc(hidden)]
+    fn join_join(mut self, join: JoinType, rel: RelationDef, via: Option<RelationDef>) -> Self {
+        if let Some(via) = via {
+            self = self.join(join, via)
+        }
+        self.join(join, rel)
+    }
+
+    /// Join via [`RelationDef`].
+    fn join(mut self, join: JoinType, rel: RelationDef) -> Self {
+        let from_tbl = rel.from_tbl.clone();
+        let to_tbl = rel.to_tbl.clone();
+        let owner_keys = rel.from_col;
+        let foreign_keys = rel.to_col;
+        let condition = match (owner_keys, foreign_keys) {
+            (Identity::Unary(o1), Identity::Unary(f1)) => {
+                Expr::tbl(Rc::clone(&from_tbl), o1).equals(Rc::clone(&to_tbl), f1)
+            } // _ => panic!("Owner key and foreign key mismatch"),
+        };
+        self.query().join(join, Rc::clone(&to_tbl), condition);
+        self
+    }
+
+    /// Join via [`RelationDef`] but in reverse direction.
+    /// Assume when there exist a relation A -> B.
+    /// You can reverse join B <- A.
+    fn join_rev(mut self, join: JoinType, rel: RelationDef) -> Self {
+        let from_tbl = rel.from_tbl.clone();
+        let to_tbl = rel.to_tbl.clone();
+        let owner_keys = rel.from_col;
+        let foreign_keys = rel.to_col;
+        let condition = match (owner_keys, foreign_keys) {
+            (Identity::Unary(o1), Identity::Unary(f1)) => {
+                Expr::tbl(Rc::clone(&from_tbl), o1).equals(Rc::clone(&to_tbl), f1)
+            } // _ => panic!("Owner key and foreign key mismatch"),
+        };
+        self.query().join(join, Rc::clone(&from_tbl), condition);
+        self
+    }
 }

src/query/join.rs

@@ -1,11 +1,8 @@
 use crate::{
-    ColumnTrait, EntityTrait, Identity, Iterable, ModelTrait, PrimaryKeyOfModel, QueryHelper,
-    Related, RelationDef, Select, SelectTwo,
+    ColumnTrait, EntityTrait, Iterable, ModelTrait, PrimaryKeyOfModel, QueryHelper, Related,
+    Select, SelectTwo,
 };
-
 pub use sea_query::JoinType;
-use sea_query::{Expr, IntoIden};
-use std::rc::Rc;
 
 impl<E> Select<E>
 where
@@ -26,45 +23,13 @@ where
         }
     }
 
-    /// Join via [`RelationDef`].
-    pub fn join(mut self, join: JoinType, rel: RelationDef) -> Self {
-        let own_tbl = E::default().into_iden();
-        let to_tbl = rel.to_tbl.clone();
-        let owner_keys = rel.from_col;
-        let foreign_keys = rel.to_col;
-        let condition = match (owner_keys, foreign_keys) {
-            (Identity::Unary(o1), Identity::Unary(f1)) => {
-                Expr::tbl(Rc::clone(&own_tbl), o1).equals(Rc::clone(&to_tbl), f1)
-            } // _ => panic!("Owner key and foreign key mismatch"),
-        };
-        self.query.join(join, Rc::clone(&to_tbl), condition);
-        self
-    }
-
-    /// Join via [`RelationDef`] but in reverse direction.
-    /// Assume when there exist a relation A -> B.
-    /// You can reverse join B <- A.
-    pub fn join_rev(mut self, join: JoinType, rel: RelationDef) -> Self {
-        let from_tbl = rel.from_tbl.clone();
-        let to_tbl = rel.to_tbl.clone();
-        let owner_keys = rel.from_col;
-        let foreign_keys = rel.to_col;
-        let condition = match (owner_keys, foreign_keys) {
-            (Identity::Unary(o1), Identity::Unary(f1)) => {
-                Expr::tbl(Rc::clone(&from_tbl), o1).equals(Rc::clone(&to_tbl), f1)
-            } // _ => panic!("Owner key and foreign key mismatch"),
-        };
-        self.query.join(join, Rc::clone(&from_tbl), condition);
-        self
-    }
-
     /// Left Join with a Related Entity.
     pub fn left_join<R>(self, _: R) -> Self
     where
         R: EntityTrait,
         E: Related<R>,
     {
-        self.join(JoinType::LeftJoin, E::to())
+        self.join_join(JoinType::LeftJoin, E::to(), E::via())
     }
 
     /// Right Join with a Related Entity.
@@ -73,7 +38,7 @@ where
         R: EntityTrait,
         E: Related<R>,
     {
-        self.join(JoinType::RightJoin, E::to())
+        self.join_join(JoinType::RightJoin, E::to(), E::via())
     }
 
     /// Inner Join with a Related Entity.
@@ -82,7 +47,7 @@ where
         R: EntityTrait,
         E: Related<R>,
     {
-        self.join(JoinType::InnerJoin, E::to())
+        self.join_join(JoinType::InnerJoin, E::to(), E::via())
     }
 
     /// Join with an Entity Related to me.
@@ -105,7 +70,7 @@ where
 
 #[cfg(test)]
 mod tests {
-    use crate::tests_cfg::{cake, fruit};
+    use crate::tests_cfg::{cake, filling, fruit};
     use crate::{ColumnTrait, EntityTrait, QueryHelper};
     use sea_query::MysqlQueryBuilder;
 
@@ -192,4 +157,20 @@ mod tests {
             .join(" ")
         );
     }
+
+    #[test]
+    fn join_6() {
+        assert_eq!(
+            cake::Entity::find()
+                .left_join(filling::Entity)
+                .build(MysqlQueryBuilder)
+                .to_string(),
+            [
+                "SELECT `cake`.`id`, `cake`.`name` FROM `cake`",
+                "LEFT JOIN `cake_filling` ON `cake`.`id` = `cake_filling`.`cake_id`",
+                "LEFT JOIN `filling` ON `cake_filling`.`filling_id` = `filling`.`id`",
+            ]
+            .join(" ")
+        );
+    }
 }

src/tests_cfg/cake.rs

@@ -24,6 +24,7 @@ pub enum PrimaryKey {
 #[derive(Copy, Clone, Debug, EnumIter)]
 pub enum Relation {
     Fruit,
+    CakeFilling,
 }
 
 impl EntityTrait for Entity {
@@ -54,6 +55,10 @@ impl RelationTrait for Relation {
                 .from(Column::Id)
                 .to(super::fruit::Column::CakeId)
                 .into(),
+            Self::CakeFilling => Entity::has_many(super::cake_filling::Entity)
+                .from(Column::Id)
+                .to(super::cake_filling::Column::CakeId)
+                .into(),
         }
     }
 }
@@ -64,6 +69,16 @@ impl Related<super::fruit::Entity> for Entity {
     }
 }
 
+impl Related<super::filling::Entity> for Entity {
+    fn to() -> RelationDef {
+        super::cake_filling::Relation::Filling.def()
+    }
+
+    fn via() -> Option<RelationDef> {
+        Some(Relation::CakeFilling.def())
+    }
+}
+
 impl Model {
     pub fn find_fruit(&self) -> Select<super::fruit::Entity> {
         Entity::find_related().belongs_to::<Entity>(self)

src/tests_cfg/cake_filling.rs

@@ -0,0 +1,65 @@
+use crate::entity::prelude::*;
+
+#[derive(Copy, Clone, Default, Debug, DeriveEntity)]
+#[table = "cake_filling"]
+pub struct Entity;
+
+#[derive(Clone, Debug, Default, PartialEq, DeriveModel)]
+pub struct Model {
+    pub cake_id: i32,
+    pub filling_id: i32,
+}
+
+#[derive(Copy, Clone, Debug, EnumIter, DeriveColumn)]
+pub enum Column {
+    CakeId,
+    FillingId,
+}
+
+#[derive(Copy, Clone, Debug, EnumIter, DerivePrimaryKey)]
+pub enum PrimaryKey {
+    CakeId,
+    FillingId,
+}
+
+#[derive(Copy, Clone, Debug, EnumIter)]
+pub enum Relation {
+    Cake,
+    Filling,
+}
+
+impl EntityTrait for Entity {
+    type Model = Model;
+
+    type Column = Column;
+
+    type PrimaryKey = PrimaryKey;
+
+    type Relation = Relation;
+}
+
+impl ColumnTrait for Column {
+    type EntityName = Entity;
+
+    fn def(&self) -> ColumnType {
+        match self {
+            Self::CakeId => ColumnType::Integer(None),
+            Self::FillingId => ColumnType::Integer(None),
+        }
+    }
+}
+
+impl RelationTrait for Relation {
+    fn def(&self) -> RelationDef {
+        match self {
+            Self::Cake => Entity::has_many(super::cake::Entity)
+                .from(Column::CakeId)
+                .to(super::cake::Column::Id)
+                .into(),
+            Self::Filling => Entity::has_many(super::filling::Entity)
+                .from(Column::FillingId)
+                .to(super::filling::Column::Id)
+                .into(),
+        }
+    }
+}

src/tests_cfg/filling.rs

@@ -0,0 +1,52 @@
+use crate::entity::prelude::*;
+
+#[derive(Copy, Clone, Default, Debug, DeriveEntity)]
+#[table = "filling"]
+pub struct Entity;
+
+#[derive(Clone, Debug, Default, PartialEq, DeriveModel)]
+pub struct Model {
+    pub id: i32,
+    pub name: String,
+}
+
+#[derive(Copy, Clone, Debug, EnumIter, DeriveColumn)]
+pub enum Column {
+    Id,
+    Name,
+}
+
+#[derive(Copy, Clone, Debug, EnumIter, DerivePrimaryKey)]
+pub enum PrimaryKey {
+    Id,
+}
+
+#[derive(Copy, Clone, Debug, EnumIter)]
+pub enum Relation {}
+
+impl EntityTrait for Entity {
+    type Model = Model;
+
+    type Column = Column;
+
+    type PrimaryKey = PrimaryKey;
+
+    type Relation = Relation;
+}
+
+impl ColumnTrait for Column {
+    type EntityName = Entity;
+
+    fn def(&self) -> ColumnType {
+        match self {
+            Self::Id => ColumnType::Integer(None),
+            Self::Name => ColumnType::String(None),
+        }
+    }
+}
+
+impl RelationTrait for Relation {
+    fn def(&self) -> RelationDef {
+        panic!()
+    }
+}

src/tests_cfg/mod.rs

@@ -1,4 +1,6 @@
 //! Configurations for test cases and examples. Not intended for actual use.
 
 pub mod cake;
+pub mod cake_filling;
+pub mod filling;
 pub mod fruit;