fix(solid-db): set key option to $key when calling reconcile

.changeset/solid-id-rendering.md

@@ -0,0 +1,5 @@
+---
+'@tanstack/solid-db': patch
+---
+
+Fix reconcile usage in useLiveQuery by setting the key field to "$key" so that items are matched correctly during reconciliation. Fixes #1524.

packages/solid-db/src/useLiveQuery.ts

@@ -346,7 +346,9 @@ export function useLiveQuery(
     currentCollection: Collection<any, any, any>,
   ) => {
     setData((prev) =>
-      reconcile(Array.from(currentCollection.values()))(prev).filter(Boolean),
+      reconcile(Array.from(currentCollection.values()), { key: '$key' })(
+        prev,
+      ).filter(Boolean),
     )
   }
 

packages/solid-db/tests/useLiveQuery.test.tsx

@@ -2587,4 +2587,58 @@ describe(`Query Collections`, () => {
       expect(rendered.result()).toBeUndefined()
     })
   })
+  describe(`custom id field`, () => {
+    it(`should keep all existing items when using a custom id field and reordering`, async () => {
+      type Item = {
+        _id: string
+        name: string
+      }
+
+      const collection = createCollection(
+        mockSyncCollectionOptions<Item>({
+          id: `custom-key-reorder-test`,
+          getKey: (item) => item._id,
+          initialData: [
+            { _id: `bob1`, name: `Bob` },
+            { _id: `kevin1`, name: `Kevin` },
+            { _id: `stuart1`, name: `Stuart` },
+          ],
+        }),
+      )
+
+      const rendered = renderHook(() =>
+        useLiveQuery((q) =>
+          q
+            .from({ items: collection })
+            .orderBy(({ items }) => items.name, `asc`),
+        ),
+      )
+
+      await waitFor(() => {
+        expect(rendered.result.isReady).toBe(true)
+      })
+
+      expect(Array.from(rendered.result()).map((item) => item.name)).toEqual([
+        `Bob`,
+        `Kevin`,
+        `Stuart`,
+      ])
+
+      collection.utils.begin()
+      collection.utils.write({
+        type: `update`,
+        value: {
+          _id: `stuart1`,
+          name: `Alvin`,
+        },
+      })
+      collection.utils.commit()
+
+      expect(Array.from(rendered.result()).map((item) => item.name)).toEqual([
+        `Alvin`,
+        `Bob`,
+        `Kevin`,
+      ])
+    })
+  })
 })