Fixed type error when using Hyperf\Validation\Rules\Unique::__toString() in PHP8. (#3969)

Co-authored-by: 李铭昕 <715557344@qq.com>

CHANGELOG-2.2.md

@@ -1,5 +1,9 @@
 # v2.2.6 - TBD
 
+## Fixed
+
+- [#3969](https://github.com/hyperf/hyperf/pull/3969) Fixed type error when using `Hyperf\Validation\Rules\Unique::__toString()` in PHP8.
+
 # v2.2.5 - 2021-08-23
 
 ## Fixed

src/validation/src/Rules/DatabaseRule.php

@@ -159,7 +159,7 @@ trait DatabaseRule
     protected function formatWheres(): string
     {
         return collect($this->wheres)->map(function ($where) {
-            return $where['column'] . ',' . '"' . str_replace('"', '""', $where['value']) . '"';
+            return $where['column'] . ',' . '"' . str_replace('"', '""', (string) $where['value']) . '"';
         })->implode(',');
     }
 }

src/validation/tests/Cases/ValidationUniqueRuleTest.php

@@ -59,6 +59,10 @@ class ValidationUniqueRuleTest extends TestCase
         $rule = new Unique('table');
         $rule->where('foo', '"bar"');
         $this->assertEquals('unique:table,NULL,NULL,id,foo,"""bar"""', (string) $rule);
+
+        $rule = new Unique('table');
+        $rule->where('foo', 1);
+        $this->assertEquals('unique:table,NULL,NULL,id,foo,"1"', (string) $rule);
     }
 }