Implement key lengths for MySQL.

Mysql is wonky and lets you set key lengths on indexes. Allow for that
and acommodate it.

Author: markstory

lib/Cake/Database/Schema/MysqlSchema.php

@@ -296,13 +296,17 @@ public function indexSql(Table $table, $name) {
 		if ($data['type'] === Table::INDEX_FULLTEXT) {
 			$out = 'FULLTEXT KEY ';
 		}
-		// TODO finish MySQL indexes with length
 		$out .= $this->_driver->quoteIdentifier($name);
 
 		$columns = array_map(
 			[$this->_driver, 'quoteIdentifier'],
 			$data['columns']
 		);
+		foreach ($data['columns'] as $i => $column) {
+			if (isset($data['length'][$column])) {
+				$columns[$i] .= sprintf('(%d)', $data['length'][$column]);
+			}
+		}
 		return $out . ' (' . implode(', ', $columns) . ')';
 	}
 

lib/Cake/Database/Schema/Table.php

@@ -78,6 +78,7 @@ class Table {
 	protected $_indexKeys = [
 		'type' => null,
 		'columns' => [],
+		'length' => [],
 	];
 
 /**

lib/Cake/Test/TestCase/Database/Schema/MysqlSchemaTest.php

@@ -461,6 +461,7 @@ public static function createTableProvider() {
 UNIQUE KEY `unique_idx` (`author_id`, `article_id`)
 );
 SQL;
+
 		$simpleKey = (new Table('things'))
 			->addColumn('thing_id', [
 				'type' => 'integer',
@@ -489,12 +490,35 @@ public static function createTableProvider() {
 `stuff` TEXT,
 FULLTEXT KEY `stuff_idx` (`stuff`)
 );
+SQL;
+
+		$keyLength = (new Table('articles_authors'))
+			->addColumn('author_id', [
+				'type' => 'integer',
+				'null' => false
+			])
+			->addColumn('article_id', [
+				'type' => 'integer',
+				'null' => false,
+			])
+			->addIndex('unique_idx', [
+				'type' => 'unique',
+				'columns' => ['author_id', 'article_id'],
+				'length' => ['author_id' => 5, 'article_id' => 4],
+			]);
+		$keyLengthExpected = <<<SQL
+CREATE TABLE `articles_authors` (
+`author_id` INTEGER NOT NULL,
+`article_id` INTEGER NOT NULL,
+UNIQUE KEY `unique_idx` (`author_id`(5), `article_id`(4))
+);
 SQL;
 		return [
 			[$basic, $basicExpected],
 			[$uniqueKey, $uniqueExpected],
 			[$fullText, $fullTextExpected],
 			[$simpleKey, $simpleKeyExpected],
+			[$keyLength, $keyLengthExpected],
 		];
 	}