本文讲述了ThinkPHP实例化模型的四种方法,对于ThinkPHP程序设计来说有非常重要的应用。具体如下:
1、创建一个基础模型:实例化一个系统自带的数据库操作类
Test.Model.class.php页面代码如下:
class TestModel extends Model{ }
UserAction.class.php页面代码如下:
function test(){ $test=M('test');//表示实例化的是自带的Model类,并且传入test值表示操作的是test表 //等同于$test=new TestModel(); $test=$test->select(); print_r($test);//输出test表中所有数据 }
2、实例化一个自定义模型
如果数据库操作比较复杂,就需要在自定义的Model类中添加一些自定义的数据库操作方法
UserModel.class.php页面代码如下:
class UserModel extends Model{ function pyj(){ echo 'pengyanjie'; //其它的一些数据库操作方法 } }
UserAction.class.php页面代码如下:
function user(){ $user=D('User');//实例化自定义的数据库操作类 //等同于$user=new UserModel(); $user->pyj();//调用User模型中的pyj方法 }
或者,你需要实例化一个表,同时呢,实例化一个自己写的自定义的数据库操作类,代码如下:
function love(){ $love=M('test','UserModel'); //$love=new UserModel('test'); $list=$love->select(); dump($list); $love->pyj(); }
3、实例化一个用户模型
UserAction.class.php页面代码如下:
function user(){ $user=new UserModel();//等同于$user=D('User'); $list=$user->select(); dump($list); echo $user->aa(); }
UserModel.class.php页面代码如下:
该类名user与表名user相对应,所以在UserAction中实例化这个模型的时候就不需要再额外的传表名了,代码如下:
class UserModel extends Model{ function aa(){ echo 'pengyanjie'; } }
这个第三种实例化模型方法与第二种的区别在于:在你的业务逻辑当中,通常情况下会有一些公共的业务逻辑,那你用第二种M('表名','模型名');如M('user','CommonModel')会更方便;
第三种实例化模型方法适于于针对所操作表的更加复杂的业务逻辑,但是它不需要使用到公共业务逻辑。(它的业务逻辑,针对用户表,它是唯一的,并且不需要在其它模型当中使用)。
4、实例化一个空模型,它并不知道你要实例化操作时用到的是哪张表。
$user=new Model();//等价与$user=M(); $list=$user->query('select * from think_user'); //使用传统的sql语句的方式,如果这样的话,就必须要加表前缀 dump($list);
附:$user=new UserModel();与$user=D('user');的区别:
(1)、D方法可以自动检测模型类,不存在时,它会抛出一个异常。同时对于已实例化过的模型,不会去重复实例化。默认的D方法,只能应用于当前项目下面的模型。
(2)、如果说,我这是前台应用,但是我想实例化后台项目的模型可以用D搞定。
$user=D('admin','user');//会去自动找admin分组下的user模型类
或者:
$user=D('admin.user');
希望本文所述实例对大家ThinkPHP程序设计有所帮助。

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