make count behave like in SQL

also fixed count behavior according to limit and offset.
fixes #1458

extensions/yii/elasticsearch/Query.php

@@ -283,13 +283,7 @@ class Query extends Component implements QueryInterface
 
 		$options = [];
 		$options['search_type'] = 'count';
-		$count = $this->createCommand($db)->search($options)['hits']['total'];
-		if ($this->limit === null && $this->offset === null) {
-			return $count;
-		} elseif ($this->offset !== null) {
-			$count = $this->offset < $count ? $count - $this->offset : 0;
-		}
-		return $this->limit === null ? $count : ($this->limit > $count ? $count : $this->limit);
+		return $this->createCommand($db)->search($options)['hits']['total'];
 	}
 
 	/**

extensions/yii/redis/ActiveQuery.php

@@ -126,7 +126,7 @@ class ActiveQuery extends \yii\base\Component implements ActiveQueryInterface
 	 */
 	public function count($q = '*', $db = null)
 	{
-		if ($this->offset === null && $this->limit === null && $this->where === null) {
+		if ($this->where === null) {
 			/** @var ActiveRecord $modelClass */
 			$modelClass = $this->modelClass;
 			if ($db === null) {
@@ -291,11 +291,17 @@ class ActiveQuery extends \yii\base\Component implements ActiveQueryInterface
 		/** @var ActiveRecord $modelClass */
 		$modelClass = $this->modelClass;
 
+		if ($type == 'Count') {
+			$start = 0;
+			$limit = null;
+		} else {
 			$start = $this->offset === null ? 0 : $this->offset;
+			$limit = $this->limit;
+		}
 		$i = 0;
 		$data = [];
 		foreach($pks as $pk) {
-			if (++$i > $start && ($this->limit === null || $i <= $start + $this->limit)) {
+			if (++$i > $start && ($limit === null || $i <= $start + $limit)) {
 				$key = $modelClass::keyPrefix() . ':a:' . $modelClass::buildKey($pk);
 				$result = $db->executeCommand('HGETALL', [$key]);
 				if (!empty($result)) {

framework/yii/db/Query.php

@@ -253,7 +253,11 @@ class Query extends Component implements QueryInterface
 	 */
 	public function exists($db = null)
 	{
-		return $this->queryScalar(new Expression('1'), $db) !== false;
+		$select = $this->select;
+		$this->select = [new Expression('1')];
+		$command = $this->createCommand($db);
+		$this->select = $select;
+		return $command->queryScalar() !== false;
 	}
 
 	/**
@@ -266,9 +270,18 @@ class Query extends Component implements QueryInterface
 	private function queryScalar($selectExpression, $db)
 	{
 		$select = $this->select;
+		$limit = $this->limit;
+		$offset = $this->offset;
+
 		$this->select = [$selectExpression];
+		$this->limit = null;
+		$this->offset = null;
 		$command = $this->createCommand($db);
+
 		$this->select = $select;
+		$this->limit = $limit;
+		$this->offset = $offset;
+
 		return $command->queryScalar();
 	}
 

tests/unit/extensions/redis/ActiveRecordTest.php

@@ -205,14 +205,6 @@ class ActiveRecordTest extends RedisTestCase
 		$this->assertEquals(2, $order->items[1]->id);
 	}
 
-	public function testFindCount()
-	{
-		$this->assertEquals(3, Customer::find()->count());
-		$this->assertEquals(1, Customer::find()->limit(1)->count());
-		$this->assertEquals(2, Customer::find()->limit(2)->count());
-		$this->assertEquals(1, Customer::find()->offset(2)->limit(2)->count());
-	}
-
 	public function testFindColumn()
 	{
 		$this->assertEquals(['user1', 'user2', 'user3'], Customer::find()->column('name'));

tests/unit/framework/ar/ActiveRecordTestTrait.php

@@ -287,10 +287,17 @@ trait ActiveRecordTestTrait
 	{
 		/** @var TestCase|ActiveRecordTestTrait $this */
 		$this->assertEquals(3, $this->callCustomerFind()->count());
-		// TODO should limit have effect on count()
-//		$this->assertEquals(1, $this->callCustomerFind()->limit(1)->count());
-//		$this->assertEquals(2, $this->callCustomerFind()->limit(2)->count());
-//		$this->assertEquals(1, $this->callCustomerFind()->offset(2)->limit(2)->count());
+
+		$this->assertEquals(1, $this->callCustomerFind()->where(['id' => 1])->count());
+		$this->assertEquals(2, $this->callCustomerFind()->where(['id' => [1, 2]])->count());
+		$this->assertEquals(2, $this->callCustomerFind()->where(['id' => [1, 2]])->offset(1)->count());
+		$this->assertEquals(2, $this->callCustomerFind()->where(['id' => [1, 2]])->offset(2)->count());
+
+		// limit should have no effect on count()
+		$this->assertEquals(3, $this->callCustomerFind()->limit(1)->count());
+		$this->assertEquals(3, $this->callCustomerFind()->limit(2)->count());
+		$this->assertEquals(3, $this->callCustomerFind()->limit(10)->count());
+		$this->assertEquals(3, $this->callCustomerFind()->offset(2)->limit(2)->count());
 	}
 
 	public function testFindLimit()
@@ -371,6 +378,10 @@ trait ActiveRecordTestTrait
 		$this->assertFalse($this->callCustomerFind()->where(['id' => 5])->exists());
 		$this->assertTrue($this->callCustomerFind()->where(['name' => 'user1'])->exists());
 		$this->assertFalse($this->callCustomerFind()->where(['name' => 'user5'])->exists());
+
+		$this->assertTrue($this->callCustomerFind()->where(['id' => [2,3]])->exists());
+		$this->assertTrue($this->callCustomerFind()->where(['id' => [2,3]])->offset(1)->exists());
+		$this->assertFalse($this->callCustomerFind()->where(['id' => [2,3]])->offset(2)->exists());
 	}
 
 	public function testFindLazy()