Add find_linked_recursive method to ModelTrait

Author: rumpuslabs

src/entity/link.rs

@@ -31,7 +31,7 @@ pub trait Linked {
     }
 }
 
-fn find_linked<I, E>(links: I, join: JoinType) -> Select<E>
+pub(crate) fn find_linked<I, E>(links: I, join: JoinType) -> Select<E>
 where
     I: Iterator<Item = LinkDef>,
     E: EntityTrait,

src/entity/model.rs

@@ -1,7 +1,7 @@
 use crate::{
-    ActiveModelBehavior, ActiveModelTrait, ConnectionTrait, DbErr, DeleteResult, EntityTrait,
-    IntoActiveModel, Linked, QueryFilter, QueryResult, Related, Select, SelectModel, SelectorRaw,
-    Statement,
+    find_linked, ActiveModelBehavior, ActiveModelTrait, ConnectionTrait, DbErr, DeleteResult,
+    EntityTrait, IntoActiveModel, Linked, QueryFilter, QueryResult, QueryTrait, Related, Select,
+    SelectModel, SelectorRaw, Statement,
 };
 use async_trait::async_trait;
 pub use sea_query::{Alias, CommonTableExpression, IntoTableRef, JoinType, UnionType, Value};
@@ -37,6 +37,38 @@ pub trait ModelTrait: Clone + Send + Debug {
         l.find_linked().belongs_to_tbl_alias(self, tbl_alias)
     }
 
+    /// Find linked Models, recursively
+    fn find_linked_recursive<L>(&self, l: L) -> Select<L::ToEntity>
+    where
+        L: Linked<FromEntity = Self::Entity, ToEntity = Self::Entity>,
+    {
+        let cte_name = Alias::new("cte");
+
+        let mut link = l.link();
+        let tbl_alias = &format!("r{}", link.len() - 1);
+        let mut cte_query = l.find_linked().belongs_to_tbl_alias(self, tbl_alias).query;
+
+        let mut last = link.pop().expect("non-zero links");
+        last.from_tbl = cte_name.clone().into_table_ref();
+        link.push(last);
+        let recursive_query: Select<L::ToEntity> =
+            find_linked(link.into_iter(), JoinType::InnerJoin);
+
+        cte_query.union(UnionType::All, recursive_query.into_query());
+        let cte = CommonTableExpression::new()
+            .table_name(cte_name.clone())
+            .query(cte_query)
+            .to_owned();
+
+        let mut select = Self::Entity::find();
+        select
+            .query
+            .from_clear()
+            .from_as(cte_name, Self::Entity::default())
+            .with_cte(cte);
+        select
+    }
+
     /// Delete a model
     async fn delete<'a, A, C>(self, db: &'a C) -> Result<DeleteResult, DbErr>
     where