From a5ba5d06ef64d56acdb6b96f0e515659cd7d0e35 Mon Sep 17 00:00:00 2001
From: Adrian Cojocariu <aco@umbraco.dk>
Date: Thu, 7 Nov 2024 14:55:23 +0200
Subject: [PATCH] Update UIBuilder related collection documentation

---
 .../advanced/repositories.md                  | 10 ++++
 .../collections/related-collections.md        | 46 +++++++++++++++++++
 2 files changed, 56 insertions(+)

diff --git a/13/umbraco-ui-builder/advanced/repositories.md b/13/umbraco-ui-builder/advanced/repositories.md
index a460ef49b59..f49db720184 100644
--- a/13/umbraco-ui-builder/advanced/repositories.md
+++ b/13/umbraco-ui-builder/advanced/repositories.md
@@ -45,6 +45,16 @@ public class PersonRepository : Repository<Person, int> {
     protected override long GetCountImpl(Expression<Func<Person, bool>> whereClause) {
         ...
     }
+
+    protected override IEnumerable<TJunctionEntity> GetRelationsByParentIdImpl<TJunctionEntity>(int parentId, string relationAlias)
+    {
+        ...
+    }
+
+    protected override TJunctionEntity SaveRelationImpl<TJunctionEntity>(TJunctionEntity entity)
+    {
+        ...
+    }
 }
 ````
 
diff --git a/13/umbraco-ui-builder/collections/related-collections.md b/13/umbraco-ui-builder/collections/related-collections.md
index 5d9effa73dc..69dbaf158d4 100644
--- a/13/umbraco-ui-builder/collections/related-collections.md
+++ b/13/umbraco-ui-builder/collections/related-collections.md
@@ -114,3 +114,49 @@ collectionConfig.Editor(editorConfig =>
 {% hint style="info" %}
 **Relation Config Alias:** The relation config alias must correspond to the related collection picker field alias! (e.g. `studentsCourses`)
 {% endhint %}
+
+## Defining repository methods
+
+### **IEnumerable<StudentCourse> GetRelationsByParentIdImpl<StudentCourse>(int parentId, string relationAlias)**
+
+Retrieves the related collections based on the ID of the parent entity.
+
+```csharp
+{
+    var db = _scopeProvider.CreateScope().Database;
+    var sql = db.SqlContext.Sql()
+            .Select(new[] { "StudentId", "CourseId" } )
+            .From("StudentsCourses")
+            .Where($"studentId = @0", parentId);
+
+    var result = db.Fetch<StudentCourse>(sql);
+
+    return result;
+}
+```
+
+### **StudentCourse SaveRelationImpl<StudentCourse>(StudentCourse entity)**
+
+Adds a new related collection to the current parent entity.
+
+```csharp
+{
+    var db = _scopeProvider.CreateScope().Database;
+
+    var type = entity.GetType();
+    var studentId = type.GetProperty("StudentId").GetValue(entity);
+    var courseId = type.GetProperty("CourseId").GetValue(entity);
+
+    // delete relation if exists
+    db.Execute("DELETE FROM StudentsCourses WHERE StudentId = @0 AND CourseId = @1",
+        studentId,
+        courseId);
+
+    db.Execute("INSERT INTO StudentsCourses (StudentId, CourseId) VALUES (@0, @1)",
+        studentId,
+        courseId);
+
+    return entity;
+}
+```
+