Implementing support for subqueries in where clause

lib/Cake/Model/Datasource/Database/Expression/Comparisson.php

@@ -0,0 +1,58 @@
+<?php
+
+namespace Cake\Model\Datasource\Database\Expression;
+
+class Comparisson extends QueryExpression {
+
+	protected $_field;
+
+	protected $_value;
+
+	protected $_type;
+
+	public function __construct(array $condition, $types = [], $conjuntion = '=') {
+		parent::__construct($condition, $types, $conjuntion);
+	}
+
+	public function field($field) {
+		$this->_field = $field;
+	}
+
+	public function value($value) {
+		$this->_value = $value;
+	}
+
+	public function getField() {
+		return $this->_field;
+	}
+
+	public function getValue() {
+		return $this->_value;
+	}
+
+	public function sql() {
+		$value = $this->_value;
+		$template = '%s %s (%s)';
+		if (is_scalar($this->_value)) {
+			$value = $this->_bindValue($this->_field,$value, $this->_type);
+			$template = '%s %s %s';
+		}
+
+		return sprintf($template, $this->_field, $this->_conjunction, $value);
+	}
+
+	public function count() {
+		return 1;
+	}
+
+	protected function _addConditions(array $condition, array $types) {
+		$this->_conditions[] = current($condition);
+		$this->_field = key($condition);
+		$this->_value = current($condition);
+
+		if (isset($types[$this->_field])) {
+			$this->_type = current($types);
+		}
+	}
+
+}

lib/Cake/Model/Datasource/Database/Expression/QueryExpression.php

@@ -1,6 +1,8 @@
 <?php
 
 namespace Cake\Model\Datasource\Database\Expression;
+
+use Cake\Model\Datasource\Database\Query;
 use \Countable;
 
 class QueryExpression implements Countable {
@@ -240,6 +242,10 @@ protected function _parseCondition($field, $value, $types) {
 			$template = '%s %s (%s)';
 		}
 
+		if ($value instanceof Query) {
+			return new Comparisson([$expression => $value], [$field => $type], $operator);
+		}
+
 		return sprintf($template, $expression,  $operator, $this->_bindValue($field, $value, $type));
 	}
 

lib/Cake/Model/Datasource/Database/Query.php

@@ -4,6 +4,7 @@
 use Iterator;
 use IteratorAggregate;
 use Cake\Model\Datasource\Database\Expression\QueryExpression;
+use Cake\Model\Datasource\Database\Expression\Comparisson;
 
 class Query implements IteratorAggregate  {
 
@@ -399,12 +400,20 @@ protected function _conjugate($part, $append, $conjunction, $types) {
 	protected function _bindParams($statement) {
 		$visitor = function($expression) use($statement) {
 			$params = $types = [];
+
+			if ($expression instanceof Comparisson) {
+				if ($expression->getValue() instanceof self) {
+					$expression->getValue()->_bindParams($statement);
+				}
+			}
+
 			foreach ($expression->bindings() as $b) {
 				$params[$b['placeholder']] = $b['value'];
 				$types[$b['placeholder']] = $b['type'];
 			}
 			$statement->bind($params, $types);
 		};
+
 		$binder = function($expression, $name) use($statement, $visitor, &$binder) {
 			if (is_array($expression)) {
 				foreach ($expression as $e) {

lib/Cake/Test/TestCase/Model/Datasource/Database/QueryTest.php

@@ -1328,4 +1328,32 @@ public function testSuqueryInFrom() {
 		$this->assertEquals($expected, $result->fetchAll('assoc'));
 	}
 
+/**
+ * Tests that Query objects can be included inside the where clause
+ * and be used as a normal condition, including binding any passed parameter
+ *
+ * @return void
+ **/
+	public function testSuqueryInWhere() {
+		$this->_insertDateRecords();
+		$this->_insertTwoRecords();
+
+		$query = new Query($this->connection);
+		$subquery = (new Query($this->connection))
+			->select(['id'])
+			->from('authors')
+			->where(['id >' => 1]);
+		$result = $query
+			->select(['name'])
+			->from(['dates'])
+			->where(['id !=' => $subquery])
+			->execute();
+
+		$expected = [
+			['name' => 'Chuck Norris'],
+			['name' => 'Jet Li']
+		];
+		$this->assertEquals($expected, $result->fetchAll('assoc'));
+	}
+
 }