From 472fc4ebb4a6459bb8485e0a60c14485b2ec56a3 Mon Sep 17 00:00:00 2001
From: Maxime Rainville <maxime@silverstripe.com>
Date: Mon, 31 May 2021 16:50:58 +1200
Subject: [PATCH] BUG Update DataQuery::exists to return false when limit
 causes no result to be returned (#9946)

* BUG Update DataQuery::exists to return false when limit causes no result to be returned

* Update comment

* Fixing linting issue
---
 src/ORM/DataQuery.php           |  3 +--
 tests/php/ORM/DataQueryTest.php | 48 ++++++++++++++++++++++++++++++---
 2 files changed, 46 insertions(+), 5 deletions(-)

diff --git a/src/ORM/DataQuery.php b/src/ORM/DataQuery.php
index c15bb569d..fa817240b 100644
--- a/src/ORM/DataQuery.php
+++ b/src/ORM/DataQuery.php
@@ -465,10 +465,9 @@ class DataQuery
         // statement anyway
         $statement = $this->getFinalisedQuery();
 
-        // Clear limit, distinct, and order as it's not relevant for an exists query
+        // Clear distinct, and order as it's not relevant for an exists query
         $statement->setDistinct(false);
         $statement->setOrderBy(null);
-        $statement->setLimit(null);
 
         // We can remove grouping if there's no "having" that might be relying on an aggregate
         // Additionally, the columns being selected no longer matter
diff --git a/tests/php/ORM/DataQueryTest.php b/tests/php/ORM/DataQueryTest.php
index 1b9a3a1a4..9f7476376 100644
--- a/tests/php/ORM/DataQueryTest.php
+++ b/tests/php/ORM/DataQueryTest.php
@@ -466,8 +466,50 @@ class DataQueryTest extends SapphireTest
 
     public function testExistsCreatesFunctionalQueries()
     {
-        $this->assertTrue(ObjectE::get()->exists());
-        $this->assertFalse(ObjectE::get()->where(['"Title" = ?' => 'Foo'])->exists());
-        $this->assertTrue(ObjectE::get()->dataQuery()->groupby('"SortOrder"')->exists());
+        $this->assertTrue(
+            ObjectE::get()->exists(),
+            'Query for ObjectE exists because there\'s more than 1 record'
+        );
+        $this->assertFalse(
+            ObjectE::get()->where(['"Title" = ?' => 'Foo'])->exists(),
+            'Query for ObjectE with Title Foo does NOT exists because there\'s no matching record'
+        );
+        $this->assertTrue(
+            ObjectE::get()->dataQuery()->groupby('"SortOrder"')->exists(),
+            'Existence of query for ObjectE is not affected by group by'
+        );
+        $this->assertTrue(
+            ObjectE::get()->limit(1)->exists(),
+            'Existence of query for ObjectE is not affected by limit if records are returned'
+        );
+        $this->assertFalse(
+            ObjectE::get()->limit(4, 9999)->exists(),
+            'Existence of query for ObjectE is affected by limit if no records are returned'
+        );
+
+        $query = new DataQuery(ObjectE::class);
+        $this->assertTrue(
+            $query->exists(),
+            'exist returns true if query return results'
+        );
+        $query = new DataQuery(ObjectE::class);
+        $this->assertFalse(
+            $query->where(['"Title" = ?' => 'Foo'])->exists(),
+            'exist returns false if there\'s no results'
+        );
+        $query = new DataQuery(ObjectE::class);
+        $this->assertTrue(
+            $query->groupby('"SortOrder"')->exists(),
+            'exist is unaffected by group by'
+        );
+        $query = new DataQuery(ObjectE::class);
+        $this->assertTrue(
+            $query->limit(1)->exists(),
+            'exist is unaffected by limit as long as one recard is returned'
+        );
+        $this->assertFalse(
+            $query->limit(1, 9999)->exists(),
+            'exist is false when a limit returns no results'
+        );
     }
 }