has_one and belongs_to

src/entity/base_entity.rs

@@ -28,18 +28,25 @@ pub trait EntityTrait: EntityName {
 
     type PrimaryKey: PrimaryKeyTrait + PrimaryKeyToColumn<Column = Self::Column>;
 
-    fn has_one<R>(related: R) -> RelationBuilder<Self, R>
+    fn belongs_to<R>(related: R) -> RelationBuilder<Self, R>
     where
         R: EntityTrait,
     {
         RelationBuilder::new(RelationType::HasOne, Self::default(), related)
     }
 
+    fn has_one<R>(_: R) -> RelationBuilder<Self, R>
+    where
+        R: EntityTrait + Related<Self>,
+    {
+        RelationBuilder::from_rel(RelationType::HasOne, R::to().rev())
+    }
+
     fn has_many<R>(_: R) -> RelationBuilder<Self, R>
     where
         R: EntityTrait + Related<Self>,
     {
-        RelationBuilder::from_rel_def(R::to().rev())
+        RelationBuilder::from_rel(RelationType::HasMany, R::to().rev())
     }
 
     /// ```

src/entity/relation.rs

@@ -78,10 +78,10 @@ where
         }
     }
 
-    pub(crate) fn from_rel_def(rel: RelationDef) -> Self {
+    pub(crate) fn from_rel(rel_type: RelationType, rel: RelationDef) -> Self {
         Self {
             entities: PhantomData,
-            rel_type: rel.rel_type,
+            rel_type,
             from_tbl: rel.from_tbl,
             to_tbl: rel.to_tbl,
             from_col: Some(rel.from_col),

src/tests_cfg/cake_filling.rs

@@ -54,11 +54,11 @@ impl ColumnTrait for Column {
 impl RelationTrait for Relation {
     fn def(&self) -> RelationDef {
         match self {
-            Self::Cake => Entity::has_one(super::cake::Entity)
+            Self::Cake => Entity::belongs_to(super::cake::Entity)
                 .from(Column::CakeId)
                 .to(super::cake::Column::Id)
                 .into(),
-            Self::Filling => Entity::has_one(super::filling::Entity)
+            Self::Filling => Entity::belongs_to(super::filling::Entity)
                 .from(Column::FillingId)
                 .to(super::filling::Column::Id)
                 .into(),

src/tests_cfg/fruit.rs

@@ -55,7 +55,7 @@ impl ColumnTrait for Column {
 impl RelationTrait for Relation {
     fn def(&self) -> RelationDef {
         match self {
-            Self::Cake => Entity::has_one(super::cake::Entity)
+            Self::Cake => Entity::belongs_to(super::cake::Entity)
                 .from(Column::CakeId)
                 .to(super::cake::Column::Id)
                 .into(),