在之前的博客中，我們定義了ORM的接口，以及決定了使用PDO去實現。最后我們提到會有一個Model類實現ModelInterface接口。
現在我們來實現這個接口，如下：
<?php
namespace sf\db;
use PDO;
/**
* Model is the base class for data models.
* @author Harry Sun <sunguangjun@126.com>
*/
class Model implements ModelInterface
{
/**
* Declares the name of the database table associated with this Model class.
* @return string the table name
*/
public static function tableName()
{
return get_called_class();
}
/**
* Returns the primary key **name(s)** for this Model class.
* @return string[] the primary key name(s) for this Model class.
*/
public static function primaryKey()
{
return ['id'];
}
/**
* Returns a single model instance by a primary key or an array of column values.
*
* ```php
* // find the first customer whose age is 30 and whose status is 1
* $customer = Customer::findOne(['age' => 30, 'status' => 1]);
* ```
*
* @param mixed $condition a set of column values
* @return static|null Model instance matching the condition, or null if nothing matches.
*/
public static function findOne($condition)
{
}
/**
* Returns a list of models that match the specified primary key value(s) or a set of column values.
*
* ```php
* // find customers whose age is 30 and whose status is 1
* $customers = Customer::findAll(['age' => 30, 'status' => 1]);
* ```
*
* @param mixed $condition a set of column values
* @return array an array of Model instance, or an empty array if nothing matches.
*/
public static function findAll($condition)
{
}
/**
* Updates models using the provided attribute values and conditions.
* For example, to change the status to be 2 for all customers whose status is 1:
*
* ~~~
* Customer::updateAll(['status' => 1], ['status' => '2']);
* ~~~
*
* @param array $attributes attribute values (name-value pairs) to be saved for the model.
* @param array $condition the condition that matches the models that should get updated.
* An empty condition will match all models.
* @return integer the number of rows updated
*/
public static function updateAll($condition, $attributes)
{
}
/**
* Deletes models using the provided conditions.
* WARNING: If you do not specify any condition, this method will delete ALL rows in the table.
*
* For example, to delete all customers whose status is 3:
*
* ~~~
* Customer::deleteAll([status = 3]);
* ~~~
*
* @param array $condition the condition that matches the models that should get deleted.
* An empty condition will match all models.
* @return integer the number of rows deleted
*/
public static function deleteAll($condition)
{
}
/**
* Inserts the model into the database using the attribute values of this record.
*
* Usage example:
*
* ```php
* $customer = new Customer;
* $customer->name = $name;
* $customer->email = $email;
* $customer->insert();
* ```
*
* @return boolean whether the model is inserted successfully.
*/
public function insert()
{
}
/**
* Saves the changes to this model into the database.
*
* Usage example:
*
* ```php
* $customer = Customer::findOne(['id' => $id]);
* $customer->name = $name;
* $customer->email = $email;
* $customer->update();
* ```
*
* @return integer|boolean the number of rows affected.
* Note that it is possible that the number of rows affected is 0, even though the
* update execution is successful.
*/
public function update()
{
}
/**
* Deletes the model from the database.
*
* @return integer|boolean the number of rows deleted.
* Note that it is possible that the number of rows deleted is 0, even though the deletion execution is successful.
*/
public function delete()
{
}
}
當然現在里面還沒有寫任何的實現，只是繼承了ModelInterface接口。
現在我們先來實現一下findOne方法，在開始實現之前我們要想，我們所有的model都要基於PDO，所以我們應該在model中有一個PDO的實例。所以我們需要在Model類中添加如下變量和方法。
/**
* @var $pdo PDO instance
*/
public static $pdo;
/**
* Get pdo instance
* @return PDO
*/
public static function getDb()
{
if (empty(static::$pdo)) {
$host = 'localhost';
$database = 'sf';
$username = 'jun';
$password = 'jun';
static::$pdo = new PDO("mysql:host=$host;dbname=$database", $username, $password);
static::$pdo->exec("set names 'utf8'");
}
return static::$pdo;
}
用static變量可以保證所有繼承該Model的類用的都是同一個PDO實例，getDb方法實現了單例模式（其中的配置暫時hard在這里，在之后的博客里會抽出來），保證了一個請求中，使用getDb只會取到一個PDO實例。
下面我們來實現findOne方法，我們現在定義的findOne有很多局限，例如不支持or，不支持select部分字段，不支持表關聯等等。我們之后會慢慢完善這一些內容。其實findOne的實現就是拼接sql語句去執行，直接來看下代碼：
public static function findOne($condition)
{
// 拼接默認的前半段sql語句
$sql = 'select * from ' . static::tableName() . ' where ';
// 取出condition中value作為參數
$params = array_values($condition);
$keys = [];
foreach ($condition as $key => $value) {
array_push($keys, "$key = ?");
}
// 拼接sql完成
$sql .= implode(' and ', $keys);
$stmt = static::getDb()->prepare($sql);
$rs = $stmt->execute($params);
if ($rs) {
$row = $stmt->fetch(PDO::FETCH_ASSOC);
if (!empty($row)) {
// 創建相應model的實例
$model = new static();
foreach ($row as $rowKey => $rowValue) {
// 給model的屬性賦值
$model->$rowKey = $rowValue;
}
return $model;
}
}
// 默認返回null
return null;
}
我們需要來驗證一下我們的代碼是正確的，先在MySQL中設置一下用戶及權限，mock一下數據。
相應的SQL語句如下：
/*創建新用戶*/
CREATE USER jun@localhost IDENTIFIED BY 'jun';
/*用戶授權 授權jun用戶擁有sf數據庫的所有權限*/
GRANT ALL PRIVILEGES ON sf.* TO jun@'%' IDENTIFIED BY 'jun';
/*刷新授權*/
FLUSH PRIVILEGES;
/*創建數據庫*/
CREATE DATABASE IF NOT EXISTS `sf`;
/*選擇數據庫*/
USE `sf`;
/*創建表*/
CREATE TABLE IF NOT EXISTS `user` (
id INT(20) NOT NULL AUTO_INCREMENT,
name VARCHAR(50),
age INT(11),
PRIMARY KEY(id)
);
/*插入測試數據*/
INSERT INTO `user` (name, age) VALUES('harry', 20), ('tony', 23), ('tom', 24);
然后再在models文件夾中創建一個User.php，代碼如下：
<?php
namespace app\models;
use sf\db\Model;
/**
* User model
* @property integer $id
* @property string $name
* @property integer $age
*/
class User extends Model
{
public static function tableName()
{
return 'user';
}
}
最后只剩在Controller中使用findOne驗證一下了。修改SiteController.php的actionTest方法如下：
public function actionTest()
{
$user = User::findOne(['age' => 20, 'name' => 'harry']);
$data = [
'first' => 'awesome-php-zh_CN',
'second' => 'simple-framework',
'user' => $user
];
echo $this->toJson($data);
}
打出的如下結果：
{"first":"awesome-php-zh_CN","second":"simple-framework","user":{"id":"1","name":"harry","age":"20"}}
如果將findOne中的條件改成['age' => 20, 'name' => 'tom']，返回值就變為如下結果：
{"first":"awesome-php-zh_CN","second":"simple-framework","user":null}
好了，今天就先到這里。項目內容和博客內容也都會放到Github上，歡迎大家提建議。
code：https://github.com/CraryPrimitiveMan/simple-framework/tree/0.5
blog project：https://github.com/CraryPrimitiveMan/create-your-own-php-framework