Fix '' in MariaDB columns TEXT DEFAULT

With MariaDB 10.3+:
> create table tmp (c text default '', d varchar(5) default '');
> show columns from tmp;
| c     | text       | YES  |     | ''      |       |
| d     | varchar(5) | YES  |     |         |       |

Yii thought the default value in the c column was "''".
It should be "".

CHANGELOG-silecs.md

@@ -12,3 +12,4 @@ Miscellanous
 ------------
 
 - CTreeView used an undocumented jQuery parameter which was removed in modern versions.
+- With MariaDB 10.3+, Yii misunderstood `TEXT DEFAULT ''` with a default value of "''".

framework/db/schema/mysql/CMysqlColumnSchema.php

@@ -44,6 +44,8 @@ protected function extractDefault($defaultValue)
 	{
 		if(strncmp($this->dbType,'bit',3)===0)
 			$this->defaultValue=bindec(trim($defaultValue,'b\''));
+		elseif(substr_compare($this->dbType,'text',-4)===0)
+			$this->defaultValue=trim($defaultValue,"''");
 		elseif(($this->dbType==='timestamp' || $this->dbType==='datetime')  && ($defaultValue==='CURRENT_TIMESTAMP' || $defaultValue==='current_timestamp()'))
 			$this->defaultValue=null;
 		else

tests/framework/db/data/mysql.sql

@@ -35,7 +35,7 @@ CREATE TABLE posts
 	title VARCHAR(128) NOT NULL,
 	create_time TIMESTAMP NOT NULL,
 	author_id INTEGER NOT NULL,
-	content TEXT,
+	content TEXT DEFAULT '',
 	CONSTRAINT FK_post_author FOREIGN KEY (author_id)
 		REFERENCES users (id) ON DELETE CASCADE ON UPDATE RESTRICT
 ) ENGINE=InnoDB;
@@ -149,4 +149,4 @@ CREATE TABLE types
 	bool_col2 BOOLEAN DEFAULT 1,
 	bit_col1 BIT,
 	bit_col2 BIT(32) DEFAULT b'101010'
-) ENGINE=InnoDB;
+) ENGINE=InnoDB;

tests/framework/db/schema/CMysqlTest.php

@@ -94,7 +94,7 @@ public function testColumn()
 		(
 			'name'=>array('id', 'title', 'create_time', 'author_id', 'content'),
 			'rawName'=>array('`id`', '`title`', '`create_time`', '`author_id`', '`content`'),
-			'defaultValue'=>array(null, null, null, null, null),
+			'defaultValue'=>array(null, null, null, null, ''),
 			'size'=>array(11, 128, null, 11, null),
 			'precision'=>array(11, 128, null, 11, null),
 			'scale'=>array(null, null, null, null, null),
@@ -314,4 +314,4 @@ public function testColumnComments()
 		$this->assertEquals('Hashed password',$usersColumns['password']->comment);
 		$this->assertEquals('',$usersColumns['email']->comment);
 	}
-}
+}