[6.x] Work search results out once when paginating

src/Query/IteratorBuilder.php

@@ -7,20 +7,33 @@
 abstract class IteratorBuilder extends Builder
 {
     protected $randomize = false;
+    private $itemsBeingPaginated;
 
     public function count()
     {
         return $this->getFilteredAndLimitedItems()->count();
     }
 
+    public function paginate($perPage = null, $columns = ['*'], $pageName = 'page', $page = null)
+    {
+        // The total and the page are both taken from the same items, so they only need working out once.
+        $this->itemsBeingPaginated = $this->getFilteredItems();
+
+        try {
+            return parent::paginate($perPage, $columns, $pageName, $page);
+        } finally {
+            $this->itemsBeingPaginated = null;
+        }
+    }
+
     protected function getCountForPagination()
     {
-        return $this->getFilteredItems()->count();
+        return ($this->itemsBeingPaginated ?? $this->getFilteredItems())->count();
     }
 
     public function get($columns = ['*'])
     {
-        $items = $this->getFilteredItems();
+        $items = $this->itemsBeingPaginated ?? $this->getFilteredItems();
 
         if ($this->randomize) {
             $items = $items->shuffle();
@@ -108,9 +121,16 @@ protected function intersectFromWhereClause($entries, $filteredEntries, $where)
 
     private function intersectItems($entries, $filteredEntries)
     {
-        return $entries->filter(function ($entry) use ($filteredEntries) {
-            return $filteredEntries->contains($entry);
-        });
+        if ($filteredEntries->contains(fn ($entry) => ! is_object($entry))) {
+            return $entries->filter(fn ($entry) => $filteredEntries->contains($entry));
+        }
+
+        // Both are taken from the same items, so an object can be looked up rather than compared with each of the others.
+        $filtered = $filteredEntries->mapWithKeys(fn ($entry) => [spl_object_id($entry) => true])->all();
+
+        return $entries->filter(fn ($entry) => is_object($entry)
+            ? isset($filtered[spl_object_id($entry)])
+            : $filteredEntries->contains($entry));
     }
 
     protected function filterWhereIn($entries, $where)

tests/Search/QueryBuilderTest.php

@@ -732,10 +732,37 @@ public function results_are_found_using_where_status()
         $this->assertCount(1, $results);
         $this->assertEquals(['b'], $results->map->reference->all());
     }
+
+    #[Test]
+    public function paginating_works_the_results_out_once()
+    {
+        $items = collect(range(1, 25))->map(fn ($i) => ['reference' => 'item'.$i, 'status' => $i % 5 ? 'published' : 'draft', 'site' => $i % 2 ? 'en' : 'fr']);
+
+        $query = (new FakeQueryBuilder($items))->withoutData()->where('status', 'published')->where('site', 'en');
+
+        $paginator = $query->paginate(4, ['*'], 'page', 2);
+
+        $this->assertSame(1, $query->searches);
+        $this->assertSame(10, $paginator->total());
+        $this->assertEquals(['item11', 'item13', 'item17', 'item19'], collect($paginator->items())->map->reference->all());
+    }
+
+    #[Test]
+    public function a_query_can_be_used_again_after_paginating()
+    {
+        $items = collect(range(1, 6))->map(fn ($i) => ['reference' => 'item'.$i, 'site' => $i % 2 ? 'en' : 'fr']);
+
+        $query = (new FakeQueryBuilder($items))->withoutData()->where('site', 'en');
+
+        $this->assertSame(3, $query->paginate(2)->total());
+        $this->assertEquals(['item3'], $query->where('reference', 'item3')->get()->map->reference->all());
+        $this->assertSame(1, $query->paginate(2)->total());
+    }
 }
 
 class FakeQueryBuilder extends QueryBuilder
 {
+    public $searches = 0;
     protected $results;
 
     public function __construct($results)
@@ -746,6 +773,8 @@ public function __construct($results)
 
     public function getSearchResults($query)
     {
+        $this->searches++;
+
         return $this->results;
     }
 }