带连接表的PDO FETCH_CLASS

Question

假设我有2个php对象:

<?php
class Post {
    public $id;
    public $text;
    public $user_id;
}
?>

和

<?php
class User {
    public $id
    public $name
}
?>

每个帖子都有一个唯一约束,数据库中有1个用户.

我想用PDO"FETCH_CLASS"方法将数据填充到"Post"对象中,该方法适用于所有"Post"属性但是如何填充"User"中的属性？

我的SQL语句如下所示:

SELECT post.id, 
       post.text, 
       post.user_id, 
       user.id, 
       user.name 
FROM POST INNER JOIN User on post.user_id = user.id

谢谢!

更新:

ATM我填写我的"Post"类,如下所示:

    $statement = $db -> prepare($query);
    $statement -> execute();
    $statement -> setFetchMode(PDO::FETCH_CLASS, 'Post');
    $posts = $statement -> fetchAll();

那么我如何更改它以填充其他类"用户"？

解:

$statement = $db -> prepare($query);
$statement -> execute();
$posts = array();
while (($row = $statement->fetch(PDO::FETCH_ASSOC)) !== false) {
    $post           = new Post();
    $post->id       = $row['post_id'];
    $post->text     = $row['post_text'];
    $post->created  = $row['post_created'];
    $post->image    = $row['post_image'];
    $post->url      = $row['post_url'];
    $post->weight   = $row['post_weight'];
    $post->likes    = $row['post_likes'];
    $user           = new User();
    $user->id       = $row['user_id'];
    $user->nickname = $row['user_nickname'];
    $user->created= $row['user_created'];
    $user->locked   = $row['user_locked'];
    $post->user     = $user;
    $posts[] = $post;
}
return $posts;

Answer 1

据我所知，PDO 中不直接支持。通常，如果您需要根据查询结果创建复杂的对象图，这就是 ORM 的职责。

如果您需要此功能，我建议您使用Doctrine或Propel，而不是自己编写一些东西。还有其他可能重量较轻的产品，但我没有使用它们的经验。

编辑：

我想也许我误解了这个问题，我确信其他人也可能误解了这个问题。我认为真正的问题是如何访问连接的列，而不是如何从它们创建对象。

在这种情况下，只需使用标准的 arry fethc 方法，例如PDO::FETCH_ASSOC, PDO::FETCH_NUMERICorPDO::FETCH_BOTH就会为您提供您查询的所有列。

因此，如果您想将其转换为“对象图”，您必须手动完成，而不是使用PDO::FETCH_CLASS.

例如：

//$db is pdo:
// also notice im aliase the columns prefixing the name so that we can tell what belongs to
// post and what belongs to user, an alternative approach would be to use FETCH_NUMERIC,
// which just uses the column positions from the seelct statement as the keys
// so in this case post.id would be in the array as key 0, and user.name would be in the
// array as key 4
$stmt = $db->prepare('SELECT post.id as p_id, 
       post.text as p_text, 
       post.user_id as p_user_id, 
       user.id as u_id, 
       user.name as u_name
FROM POST INNER JOIN User on post.user_id = user.id');

$stmt->execute();

while (($row = $stmt->fetch(PDO::FETCH_ASSOC)) !== false) {
   print_r($row);
   /* will output:
      Array (
         'p_id' => 'value'
         'p_text' => 'value'
         'p_user_id' => 'value'
         'u_id' => 'value',
         'u_name' => 'value'
      )
   So now you need to decide how to create your objects with the information returned
   */
}