[6.x] Fix navigation collections array handling

src/Http/Controllers/CP/Navigation/NavigationController.php

@@ -64,7 +64,7 @@ public function edit($nav)
         $values = [
             'title' => $nav->title(),
             'handle' => $nav->handle(),
-            'collections' => $nav->collections()->map->handle()->all(),
+            'collections' => Arr::wrap($nav->collections()->map->handle()->all()),
             'collections_query_scopes' => $nav->collectionsQueryScopes(),
             'root' => $nav->expectsRoot(),
             'sites' => $nav->trees()->keys()->all(),
@@ -138,7 +138,7 @@ public function show(Request $request, $nav)
                     'url' => $tree->showUrl(),
                 ];
             })->values()->all(),
-            'collections' => $nav->collections()->map->handle()->all(),
+            'collections' => Arr::wrap($nav->collections()->map->handle()->all()),
             'entryQueryScopes' => $nav->collectionsQueryScopes(),
             'initialMaxDepth' => $nav->maxDepth(),
             'expectsRoot' => $nav->expectsRoot(),

tests/Feature/Navigation/LinkToEntryWithMultipleCollectionsTest.php

@@ -0,0 +1,103 @@
+<?php
+
+namespace Tests\Feature\Navigation;
+
+use PHPUnit\Framework\Attributes\Test;
+use Statamic\Facades\Collection;
+use Statamic\Facades\Nav;
+use Statamic\Facades\User;
+use Tests\FakesRoles;
+use Tests\PreventSavingStacheItemsToDisk;
+use Tests\TestCase;
+
+class LinkToEntryWithMultipleCollectionsTest extends TestCase
+{
+    use FakesRoles;
+    use PreventSavingStacheItemsToDisk;
+
+    #[Test]
+    public function it_can_view_navigation_with_collections_as_array()
+    {
+        Collection::make('pages')->save();
+        Collection::make('articles')->save();
+
+        $nav = tap(Nav::make('test')->collections(['pages', 'articles']))->save();
+        $nav->makeTree('default')->save();
+
+        $this->setTestRoles(['test' => ['access cp', 'view test nav']]);
+        $user = tap(User::make()->assignRole('test'))->save();
+
+        $response = $this->actingAs($user)->get(cp_route('navigation.show', 'test'));
+
+        $response->assertOk();
+        $props = $response->viewData('page')['props'];
+        $this->assertIsArray($props['collections']);
+        $this->assertEquals(['pages', 'articles'], $props['collections']);
+    }
+
+    #[Test]
+    public function it_can_view_navigation_with_collections_as_string()
+    {
+        Collection::make('pages')->save();
+
+        // Simulate what happens when YAML has `collections: pages` instead of `collections: [pages]`
+        // The NavigationStore passes the raw YAML value (string) to the collections() setter
+        $nav = Nav::make('test');
+        $nav->collections('pages'); // Pass string directly
+        $nav->save();
+        $nav->makeTree('default')->save();
+
+        $this->setTestRoles(['test' => ['access cp', 'view test nav']]);
+        $user = tap(User::make()->assignRole('test'))->save();
+
+        $response = $this->actingAs($user)->get(cp_route('navigation.show', 'test'));
+
+        $response->assertOk();
+        $props = $response->viewData('page')['props'];
+        $this->assertIsArray($props['collections']);
+        $this->assertEquals(['pages'], $props['collections']);
+    }
+
+    #[Test]
+    public function it_can_edit_navigation_with_collections_as_string()
+    {
+        Collection::make('pages')->save();
+
+        // When a Nav is loaded from YAML with `collections: pages` (string),
+        // the NavigationStore passes that string to the collections() setter
+        $nav = Nav::make('test');
+        $nav->collections('pages'); // Pass string directly
+        $nav->save();
+
+        $this->setTestRoles(['test' => ['access cp', 'configure navs']]);
+        $user = tap(User::make()->assignRole('test'))->save();
+
+        $response = $this->actingAs($user)->get(cp_route('navigation.edit', 'test'));
+
+        $response->assertOk();
+        $this->assertIsArray($response->json('data.values.collections'));
+        $this->assertEquals(['pages'], $response->json('data.values.collections'));
+    }
+
+    #[Test]
+    public function it_can_get_page_selector_filters_when_navigation_has_multiple_collections()
+    {
+        Collection::make('pages')->save();
+        Collection::make('articles')->save();
+
+        // Test the full flow: navigation with multiple collections -> PageSelector -> filters endpoint
+        $this->setTestRoles(['test' => ['access cp', 'view pages entries', 'view articles entries']]);
+        $user = tap(User::make()->assignRole('test'))->save();
+
+        $config = base64_encode(json_encode([
+            'type' => 'entries',
+            'collections' => ['pages', 'articles'], // Array of two
+        ]));
+
+        $response = $this->actingAs($user)->getJson("/cp/fieldtypes/relationship/filters?config={$config}");
+
+        $response->assertOk();
+        $handles = collect($response->json())->pluck('handle');
+        $this->assertTrue($handles->contains('collection'));
+    }
+}