Add case expression class for simple SQL case statements

src/Database/Expression/CaseExpression.php

@@ -0,0 +1,160 @@
+<?php
+/**
+ * CakePHP(tm) : Rapid Development Framework (http://cakephp.org)
+ * Copyright (c) Cake Software Foundation, Inc. (http://cakefoundation.org)
+ *
+ * Licensed under The MIT License
+ * For full copyright and license information, please see the LICENSE.txt
+ * Redistributions of files must retain the above copyright notice.
+ *
+ * @copyright     Copyright (c) Cake Software Foundation, Inc. (http://cakefoundation.org)
+ * @link          http://cakephp.org CakePHP(tm) Project
+ * @since         3.0.0
+ * @license       http://www.opensource.org/licenses/mit-license.php MIT License
+ */
+namespace Cake\Database\Expression;
+
+use Cake\Database\ExpressionInterface;
+use Cake\Database\Expression\QueryExpression;
+use Cake\Database\ValueBinder;
+
+/**
+ * This class represents a SQL Case statement
+ *
+ * @internal
+ */
+class CaseExpression implements ExpressionInterface {
+
+	protected $_expression;
+
+	protected $_isTrue;
+
+	protected $_isFalse;
+
+/**
+ * Constructs the case expression
+ *
+ * @param QueryExpression $expression The expression to test
+ * @param mixed           $isTrue Value if the expression is true
+ * @param mixed           $isFalse Value if the expression is false
+ */
+	public function __construct(QueryExpression $expression, $isTrue = 1, $isFalse = 0) {
+		$this->_expression = $expression;
+		$this->_isTrue = $this->_getValue($isTrue);
+		$this->_isFalse = $this->_getValue($isFalse);
+	}
+
+/**
+ * Gets/sets the isTrue part
+ *
+ * @param mixed $value Value to set
+ *
+ * @return array|mixed
+ */
+	public function isTrue($value = null) {
+		return $this->_part('isTrue', $value);
+	}
+
+/**
+ * Gets/sets the isFalse part
+ *
+ * @param mixed $value Value to set
+ *
+ * @return array|mixed
+ * @codeCoverageIgnore
+ */
+	public function isFalse($value = null) {
+		return $this->_part('isFalse', $value);
+	}
+
+/**
+ * Gets/sets the passed part
+ *
+ * @param string $part The part to get or set
+ * @param mixed $value Value to set
+ *
+ * @return array|mixed
+ */
+	protected function _part($part, $value) {
+		if ($value !== null) {
+			$this->{'_' . $part} = $this->_getValue($value);
+		}
+
+		return $this->{'_' . $part};
+	}
+
+/**
+ * Parses the value into a understandable format
+ *
+ * @param mixed $value The value to parse
+ *
+ * @return array|mixed
+ */
+	protected function _getValue($value) {
+		if (is_string($value)) {
+			$value = [
+				'value' => $value,
+				'type' => null
+			];
+		} elseif (is_array($value) && !isset($value['value'])) {
+			$value = array_keys($value);
+			$value = end($value);
+		}
+		return $value;
+	}
+
+/**
+ * Compiles the true or false part into sql
+ *
+ * @param mixed       $part The part to compile
+ * @param ValueBinder $generator Sql generator
+ *
+ * @return string
+ */
+	protected function _compile($part, ValueBinder $generator) {
+		$part = $this->{'_' . $part};
+		if ($part instanceof ExpressionInterface) {
+			$part = $part->sql($generator);
+		} elseif (is_array($part)) {
+			$placeholder = $generator->placeholder('param');
+			$generator->bind($placeholder, $part['value'], $part['type']);
+			$part = $placeholder;
+		}
+
+		return $part;
+	}
+
+/**
+ * Converts the Node into a SQL string fragment.
+ *
+ * @param \Cake\Database\ValueBinder $generator Placeholder generator object
+ *
+ * @return string
+ */
+	public function sql(ValueBinder $generator) {
+		$parts = [];
+		$parts[] = 'CASE WHEN';
+		$parts[] = $this->_expression->sql($generator);
+		$parts[] = 'THEN';
+		$parts[] = $this->_compile('isTrue', $generator);
+		$parts[] = 'ELSE';
+		$parts[] = $this->_compile('isFalse', $generator);
+		$parts[] = 'END';
+
+		return implode(' ', $parts);
+	}
+
+/**
+ * {@inheritDoc}
+ *
+ */
+	public function traverse(callable $visitor) {
+		foreach (['_expression', '_isTrue', '_isFalse'] as $c) {
+			if ($this->{$c} instanceof ExpressionInterface) {
+				$visitor($this->{$c});
+				$this->{$c}->traverse($visitor);
+			}
+		}
+	}
+
+}

src/Database/Expression/QueryExpression.php

@@ -266,6 +266,10 @@ public function in($field, $values, $type = null) {
 		return $this->add(new Comparison($field, $values, $type, 'IN'));
 	}
 
+	public function addCase(QueryExpression $expression, $isTrue = 1, $isFalse = 0) {
+		return $this->add(new CaseExpression($expression, $isTrue, $isFalse));
+	}
+
 /**
  * Adds a new condition to the expression object in the form
  * "field NOT IN (value1, value2)".

tests/TestCase/Database/Expression/CaseExpressionTest.php

@@ -0,0 +1,96 @@
+<?php
+/**
+ * Project: hesa-mbit.
+ * User: walther
+ * Date: 2014/08/08
+ * Time: 9:37 AM
+ */
+
+namespace Cake\Test\TestCase\Database\Expression;
+
+use Cake\Database\Expression\QueryExpression;
+use Cake\Database\ValueBinder;
+use Cake\TestSuite\TestCase;
+use Cake\Database\Expression\CaseExpression;
+
+/**
+ * Tests CaseExpression class
+ */
+class CaseExpressionTest extends TestCase {
+
+/**
+ * Test that the sql output works correctly
+ *
+ * @return void
+ */
+	public function testSqlOutput() {
+		$expr = new QueryExpression();
+		$expr->eq('test', 'true');
+		$caseExpression = new CaseExpression($expr);
+
+		$this->assertInstanceOf('Cake\Database\ExpressionInterface', $caseExpression);
+		$expected = 'CASE WHEN test = :c0 THEN 1 ELSE 0 END';
+		$this->assertSame($expected, $caseExpression->sql(new ValueBinder()));
+	}
+
+/**
+ * Test that we can pass in things as the isTrue/isFalse part
+ *
+ * @return void
+ */
+	public function testSetTrue() {
+		$expr = new QueryExpression();
+		$expr->eq('test', 'true');
+		$caseExpression = new CaseExpression($expr);
+		$expr2 = new QueryExpression();
+
+		$caseExpression->isTrue($expr2);
+		$this->assertSame($expr2, $caseExpression->isTrue());
+
+		$caseExpression->isTrue('test_string');
+		$this->assertSame(['value' => 'test_string', 'type' => null], $caseExpression->isTrue());
+
+		$caseExpression->isTrue(['test_string' => 'literal']);
+		$this->assertSame('test_string', $caseExpression->isTrue());
+	}
+
+/**
+ * Test that things are compiled correctly
+ *
+ * @return void
+ */
+	public function testSqlCompiler() {
+		$expr = new QueryExpression();
+		$expr->eq('test', 'true');
+		$caseExpression = new CaseExpression($expr);
+		$expr2 = new QueryExpression();
+		$expr2->eq('test', 'false');
+
+		$caseExpression->isTrue($expr2);
+		$this->assertSame('CASE WHEN test = :c0 THEN test = :c1 ELSE 0 END', $caseExpression->sql(new ValueBinder()));
+
+		$caseExpression->isTrue('test_string');
+		$this->assertSame('CASE WHEN test = :c0 THEN :c1 ELSE 0 END', $caseExpression->sql(new ValueBinder()));
+
+		$caseExpression->isTrue(['test_string' => 'literal']);
+		$this->assertSame('CASE WHEN test = :c0 THEN test_string ELSE 0 END', $caseExpression->sql(new ValueBinder()));
+	}
+
+/**
+ * Tests that the expression is correctly traversed
+ *
+ * @return void
+ */
+	public function testTraverse() {
+		$count = 0;
+		$visitor = function() use (&$count) {
+			$count++;
+		};
+
+		$expr = new QueryExpression();
+		$expr->eq('test', 'true');
+		$caseExpression = new CaseExpression($expr);
+		$caseExpression->traverse($visitor);
+		$this->assertSame(2, $count);
+	}
+}