php - 无法使用 array_merge 合并变量 : undefined index

Question

我正在尝试组合两个从 MySQL 检索信息的变量。

有人建议我使用array_merge()，它似乎在大多数情况下都有效。从数据库返回所有结果后，我不断收到警告:非法字符串偏移。有趣的是，前 8 个(查询的 LIMIT 为 8)是错误清除的，在打印 8 个结果后，会出现一个包含该错误的巨大列表。

查询

articleClass.php

public function latestArticles()
{
    $sth = $this->db->prepare("SELECT * FROM articles       
                               WHERE article_uid = article_uid
                               ORDER BY article_uid DESC LIMIT 8");
    $sth->execute();
    $row = $sth->fetchAll();
    return $row;
}

public function articleTags()
{
    $sth = $this->db->prepare("SELECT a.*, b.*
                               FROM articles a, article_tags b
                               WHERE b.tag_id = a.article_uid
                               ");
    $sth->execute();
    $row = $sth->fetchAll();
    return $row;
}

打印代码

index.php

include 'libraries/articleClass/articleClass.php';

$articleClass       = new articleClass();
$latestArticles     = $articleClass->latestArticles();
    $articleTags        = $articleClass->articleTags();

foreach(array_merge($latestArticles, $articleTags) as $data)
{   
$first_uid      = $data['article_uid'];
$first_image    = $data['article_image'];
$first_title    = $data['article_title'];
$first_content  = $data['article_content'];
$first_created  = gmdate("d M Y", $data['article_created']);
$first_tags     = $data['tag_name'];

echo '
    <article>
        <img src="path-to-image/'.$first_image.'"/>
        <h1>'.$first_title.'</h1>
        <p>'.$first_content.'</p>
            <ul>
                <li>'.$first_tags.'</li>
            </ul>

    </article>
';
}

加载 index.php 后，页面上会按预期打印 8 篇文章，但我得到:

Notice: Undefined index: tag_name in /var/www/new-design/index.php on line 74

试验和(大部分)失败

如果我将公共(public)函数article_tags更改为Fetch而不是FetchAll，我会收到以下错误:

Warning: array_merge(): Argument #2 is not an array in /var/www/new-design/index.php on line 67

Warning: Invalid argument supplied for foreach() in /var/www/new-design/index.php on line 67

我不知道如何成功，任何线索都会很棒。我从早上就开始了!

更新

article_tags表

+--------------------------------+
| tag_id | article_id | tag_name |
+--------------------------------+
|   1    |     8      | awesome  |
|   2    |     8      | sweet    |
|   3    |     8      | gross    |
+--------------------------------+

被调用的文章只有一个article_id对应，但这篇文章仍然收到未定义的index: tag_name，当然是因为在array_merge中它们根本没有被合并。

Answer 1

这里发生的事情是这样的

array_merge($latestArticles, $articleTags)

简单地将一个数组附加到另​​一个数组，意思是:结果数组中的前 8 个条目是您的文章(这些条目设置了“tag_name”字段)。

其余部分填充了 $articleTags 的内容(那些没有“tag_name”字段 - 导致您的错误)。

下面是一些代码来说明这一点(索引 0 到 2 是您的文章，而 3 到 5 是您的标签，请注意结果数组的索引 3-5 没有 tag_name 字段):

$latestArticles = array(
    array("article_title" => "Some Title 1", "tag_name" => "SomeTag"),
    array("article_title" => "Some Title 2", "tag_name" => "SomeOtherTag"),
    array("article_title" => "Some Title 3", "tag_name" => "SomeTag"),
);

$articleTags = array(
    array("name" => "SomeTag", "somefield" => "foo", "otherfield" => "bar"),
    array("name" => "SomeTagOtherTag", "somefield" => "baz", "otherfield" => "test"),
    array("name" => "YetAnotherTag", "somefield" => "test2", "otherfield" => "test3")
);


$result = array_merge($latestArticles, $articleTags);
print_r($result);

/** Resulting Array:
Array
(
    [0] => Array
        (
            [article_title] => Some Title 1
            [tag_name] => SomeTag
        )

    [1] => Array
        (
            [article_title] => Some Title 2
            [tag_name] => SomeOtherTag
        )

    [2] => Array
        (
            [article_title] => Some Title 3
            [tag_name] => SomeTag
        )

    [3] => Array
        (
            [name] => SomeTag
            [somefield] => foo
            [otherfield] => bar
        )

    [4] => Array
        (
            [name] => SomeTagOtherTag
            [somefield] => baz
            [otherfield] => test
        )

    [5] => Array
        (
            [name] => YetAnotherTag
            [somefield] => test2
            [otherfield] => test3
        )

)
*/