Add hook to describe table options when reflecting a table.

This will let the schema subsystem get engine information from MySQL
when reflecting tables. Other table types do not use options so the base
class methods are noops instead of abstract methods.

Refs #4263

src/Database/Schema/BaseSchema.php

@@ -135,6 +135,17 @@ abstract public function describeIndexSql($table, $config);
  */
 	abstract public function describeForeignKeySql($table, $config);
 
+/**
+ * Generate the SQL to describe table options
+ *
+ * @param string $name Table name.
+ * @param array $config The connection configuration.
+ * @return array SQL statements to get options for a table.
+ */
+	public function describeOptionsSql($name, $config) {
+		return ['', ''];
+	}
+
 /**
  * Convert field description results into abstract schema fields.
  *
@@ -210,4 +221,14 @@ abstract public function indexSql(Table $table, $name);
  */
 	abstract public function truncateTableSql(Table $table);
 
+/**
+ * Convert options data into table options.
+ *
+ * @param \Cake\Database\Schema\Table $table Table instance.
+ * @param array $row The row of data.
+ * @return void
+ */
+	public function convertOptions(Table $table, $row) {
+	}
+
 }

src/Database/Schema/Collection.php

@@ -135,6 +135,15 @@ public function describe($name, array $options = []) {
 		}
 		$statement->closeCursor();
 
+		list($sql, $params) = $this->_dialect->describeOptionsSql($name, $config);
+		if ($sql) {
+			$statement = $this->_executeSql($sql, $params);
+			foreach ($statement->fetchAll('assoc') as $row) {
+				$this->_dialect->convertOptions($table, $row);
+			}
+			$statement->closeCursor();
+		}
+
 		if (!empty($cacheConfig)) {
 			Cache::write($cacheKey, $table, $cacheConfig);
 		}

src/Database/Schema/MysqlSchema.php

@@ -39,8 +39,24 @@ public function describeTableSql($name, $config) {
 /**
  * {@inheritDoc}
  */
-	public function describeIndexSql($table, $config) {
-		return ['SHOW INDEXES FROM ' . $this->_driver->quoteIdentifier($table), []];
+	public function describeIndexSql($name, $config) {
+		return ['SHOW INDEXES FROM ' . $this->_driver->quoteIdentifier($name), []];
+	}
+
+/**
+ * {@inheritDoc}
+ */
+	public function describeOptionsSql($name, $config) {
+		return ['SHOW TABLE STATUS WHERE Name = ?', [$name]];
+	}
+
+/**
+ * {@inheritDoc}
+ */
+	public function convertOptions(Table $table, $row) {
+		$table->options([
+			'engine' => $row['Engine']
+		]);
 	}
 
 /**

tests/TestCase/Database/Schema/MysqlSchemaTest.php

@@ -366,6 +366,20 @@ public function testDescribeTableIndexes() {
 		$this->assertEquals($expected, $result->index('author_idx'));
 	}
 
+/**
+ * Test describing a table creates options
+ *
+ * @return void
+ */
+	public function testDescribeTableOptions() {
+		$connection = ConnectionManager::get('test');
+		$this->_createTables($connection);
+
+		$schema = new SchemaCollection($connection);
+		$result = $schema->describe('schema_articles');
+		$this->assertArrayHasKey('engine', $result->options());
+	}
+
 /**
  * Column provider for creating column sql
  *