From 95266170a6db8065144ac50772f478971d705cd9 Mon Sep 17 00:00:00 2001
From: Artur Arseniev <artur.catch@hotmail.it>
Date: Thu, 23 Oct 2025 16:35:47 +0400
Subject: [PATCH] Resolve one to many relations in DataSource records

---
 .../core/src/data_sources/model/DataSource.ts | 14 +++++++++---
 packages/core/src/data_sources/types.ts       |  3 +++
 .../specs/data_sources/model/DataSource.ts    | 22 ++++++++++++++++++-
 3 files changed, 35 insertions(+), 4 deletions(-)

diff --git a/packages/core/src/data_sources/model/DataSource.ts b/packages/core/src/data_sources/model/DataSource.ts
index 4e816f429..d2a4ea3be 100644
--- a/packages/core/src/data_sources/model/DataSource.ts
+++ b/packages/core/src/data_sources/model/DataSource.ts
@@ -194,11 +194,19 @@ export default class DataSource<DRProps extends DataRecordProps = DataRecordProp
           if (relationValue) {
             const targetDs = this.em.DataSources.get(fieldSchema.target);
             if (targetDs) {
+              const targetRecords = targetDs.records;
               const targetField = fieldSchema.targetField || DEF_DATA_FIELD_ID;
-              const relatedRecord = targetDs.records.find((r) => r.attributes[targetField] === relationValue);
 
-              if (relatedRecord) {
-                result[fieldName] = relatedRecord.attributes;
+              if (fieldSchema.isMany) {
+                const relationValues = Array.isArray(relationValue) ? relationValue : [relationValue];
+                const relatedRecords = targetRecords.filter((r) => relationValues.includes(r.attributes[targetField]));
+                result[fieldName] = relatedRecords.map((r) => ({ ...r.attributes }));
+              } else {
+                const relatedRecord = targetDs.records.find((r) => r.attributes[targetField] === relationValue);
+
+                if (relatedRecord) {
+                  result[fieldName] = { ...relatedRecord.attributes };
+                }
               }
             }
           }
diff --git a/packages/core/src/data_sources/types.ts b/packages/core/src/data_sources/types.ts
index 691e000ee..cc65b76c8 100644
--- a/packages/core/src/data_sources/types.ts
+++ b/packages/core/src/data_sources/types.ts
@@ -100,6 +100,9 @@ export interface DataFieldSchemaRelation extends DataFieldSchemaBase {
    * The target field in the data source
    */
   targetField?: string;
+  /**
+   * If true, the relation is one-to-many
+   */
   isMany?: boolean;
 }
 
diff --git a/packages/core/test/specs/data_sources/model/DataSource.ts b/packages/core/test/specs/data_sources/model/DataSource.ts
index 0dc2c01ca..d26f39710 100644
--- a/packages/core/test/specs/data_sources/model/DataSource.ts
+++ b/packages/core/test/specs/data_sources/model/DataSource.ts
@@ -87,15 +87,17 @@ describe('DataSource', () => {
       const categoryRecords = [
         { id: 'cat1', uid: 'cat1-uid', name: 'Category 1' },
         { id: 'cat2', uid: 'cat2-uid', name: 'Category 2' },
+        { id: 'cat3', uid: 'cat3-uid', name: 'Category 3' },
       ];
       const userRecords = [
         { id: 'user1', username: 'user_one' },
         { id: 'user2', username: 'user_two' },
+        { id: 'user3', username: 'user_three' },
       ];
       const blogRecords = [
         { id: 'blog1', title: 'First Blog', author: 'user1', categories: ['cat1-uid'] },
         { id: 'blog2', title: 'Second Blog', author: 'user2' },
-        { id: 'blog3', title: 'Third Blog', categories: ['cat1-uid', 'cat2-uid'] },
+        { id: 'blog3', title: 'Third Blog', categories: ['cat1-uid', 'cat3-uid'] },
       ];
 
       beforeEach(() => {
@@ -137,6 +139,24 @@ describe('DataSource', () => {
           blogRecords[2],
         ]);
       });
+
+      test('return 1:many resolved values', () => {
+        const blogsDS = dsm.get('blogs');
+        blogsDS.upSchema({
+          categories: {
+            type: DataFieldPrimitiveType.relation,
+            target: 'categories',
+            targetField: 'uid',
+            isMany: true,
+          },
+        });
+        const records = blogsDS.getResolvedRecords();
+        expect(records).toEqual([
+          { ...blogRecords[0], author: userRecords[0], categories: [categoryRecords[0]] },
+          { ...blogRecords[1], author: userRecords[1] },
+          { ...blogRecords[2], categories: [categoryRecords[0], categoryRecords[2]] },
+        ]);
+      });
     });
   });
 });