Fixed QueryBuilder::buildCondition() to skip empty array on input

Fixes #15653

framework/db/QueryBuilder.php

@@ -1491,15 +1491,17 @@ class QueryBuilder extends \yii\base\BaseObject
     public function buildCondition($condition, &$params)
     {
         if (is_array($condition)) {
+            if (empty($condition)) {
+                return '';
+            }
+
             $condition = $this->createConditionFromArray($condition);
         }
 
         if ($condition instanceof ExpressionInterface) {
             return $this->buildExpression($condition, $params);
         }
-        if (empty($condition)) {
-            return '';
-        }
+
         return (string) $condition;
     }
 

framework/db/conditions/ConjunctionConditionBuilder.php

@@ -28,11 +28,15 @@ class ConjunctionConditionBuilder implements ExpressionBuilderInterface
     {
         $parts = $this->buildExpressionsFrom($condition, $params);
 
-        if (!empty($parts)) {
-            return '(' . implode(") {$condition->getOperator()} (", $parts) . ')';
+        if (empty($parts)) {
+            return '';
         }
 
-        return '';
+        if (count($parts) === 1) {
+            return reset($parts);
+        }
+
+        return '(' . implode(") {$condition->getOperator()} (", $parts) . ')';
     }
 
     /**

tests/framework/db/QueryBuilderTest.php

@@ -2359,4 +2359,22 @@ abstract class QueryBuilderTest extends DatabaseTestCase
         $this->assertEquals('SELECT *' . (empty($expected) ? '' : ' WHERE ' . $this->replaceQuotes($expected)), $sql);
         $this->assertEquals($expectedParams, $params);
     }
+
+    /**
+     * @see https://github.com/yiisoft/yii2/issues/15653
+     */
+    public function testIssue15653()
+    {
+        $query = (new Query())
+            ->from('admin_user')
+            ->where(['is_deleted' => false]);
+
+        $query
+            ->where([])
+            ->andWhere(['in', 'id', ['1', '0']]);
+
+        list($sql, $params) = $this->getQueryBuilder()->build($query);
+        $this->assertSame("SELECT * FROM `admin_user` WHERE `id` IN (:qp0, :qp1)", $sql);
+        $this->assertSame([':qp0' => '1', ':qp1' => '0'], $params);
+    }
 }