Detailed explanation of the shortcode function in WordPress, wordpressshortcode_PHP tutorial

Detailed explanation of the use of shortcode shortcode function in WordPress, wordpressshortcode

WordPress has added a shortcode (short code) API starting from version 2.5, similar to BBCode on BBS. Shortcode can also easily add functions to articles or pages, and shortcode is more flexible and powerful than BBCode. Next, Kayo will introduce shortcode to you.

1. Shortcode Introduction
Shortcode allows developers to generate content by creating macro content in the form of functions. Perhaps this concept seems a bit vague, but in fact it is a very simple and practical function, as long as you can write basic PHP functions, that is Shortcode can be used. The following will use practical examples to illustrate the use of shortcode.

2.shortcode form
Shortcode supports closed tags and self-closing (automatically closed) tags, and supports the use of parameters within tags. As for the specific form of shortcode, it depends on how the developer writes the shortcode.

[myshortcode]Some Content[/myshortcode] // 封闭标签
[myshortcode] // 自闭标签
[myshortcode title="example"] // 带有一个参数的自闭标签
[myshortcode]<p><a href="#"><span>内容</span></a></p>[/myshortcode] // 标签内可以填写文本或 HTML
[myshortcode]Content [myshortcodesecond] more content[/myshortcodesecond] // 也可以嵌套使用标签

Three.shortcode examples
Before using shortcode, you must first define shortcode in the theme’s functions.php file, for example:

function myshortcode_function($atts, $content = null){ // $atts 代表了 shortcode 的各个参数，$content 为标签内的内容
 
 extract(shortcode_atts(array( // 使用 extract 函数解析标签内的参数
 "title" => '标题' // 给参数赋默认值，下面直接调用 $ 加上参数名输出参数值
 ), $atts));
 // 返回内容
 return '<div class="myshortcode">
    <h3>'. $title .'</h3>
    <p>
     '. $content .'
    </p>
   </div>';
}
 
add_shortcode("msc", "myshortcode_function"); // 注册该 shortcode，以后使用 [msc] 标签调用该 shortcode

Add the above code to functions.php, and a simple shortcode will be created. We can call the shortcode through the [msc][/msc] tag, such as:

[msc title="欢迎"]这是独立博客 Kayo's Melody ，欢迎来到本博客[/msc]

Enter the above call in the article or page content, and you can output a welcome statement at the corresponding location. Define the corresponding CSS in style.css to give the short code a style.

Kayo briefly introduced the shortcode function of WordPress, mainly introducing the main concepts and usage of shortcode. In this article, Kayo will introduce the more important APIs in shortcode in more detail, hoping to help you develop more complex shortcodes.

4. Function add_shortcode

This function is used to register a shortcode. It has two parameters: the shortcode name and the shortcode processing function name. Quoting the above example:

function myshortcode_function($atts, $content = null){ // $atts 代表了 shortcode 的各个参数，$content 为标签内的内容
 
 extract(shortcode_atts(array( // 使用 extract 函数解析标签内的参数
 "title" => '标题' // 给参数赋默认值，下面直接调用 $ 加上参数名输出参数值
 ), $atts));
 // 返回内容
 return '<div class="myshortcode">
    <h3>'. $title .'</h3>
    <p>
     '. $content .'
    </p>
   </div>';
}
 
add_shortcode("msc", "myshortcode_function"); // 注册该 shortcode，以后使用 [msc] 标签调用该 shortcode

msc is the shortcode name. You can directly use the [msc][/msc] tag to call the shortcode when writing articles or pages in the future, and "myshortcode_function" is the name of the shortcode processing function in the example. The following focuses on analyzing the short code processing function.

5. Short code processing function

The shortcode processing function is the core of a shortcode. The shortcode processing function is similar to Flickr (WordPress filter). They all accept specific parameters and return certain results. The shortcode processor accepts two parameters, $attr and $content. $attr represents the various attribute parameters of shortcode, which is essentially an associative array, and $content represents the content in the shortcode tag.

As in the above example, if a call is made within the article, a welcome statement will be output:

[msc title="Welcome"]This is an independent blog Kayo's Melody, welcome to this blog[/msc]
When the article is displayed, WordPress will register all shortcodes, such as [msc] above. If there are attribute parameters and content in the shortcode, WordPress will separate and parse them, and then pass them to the shortcode processing function of the shortcode. After processing The result output by the processing function is displayed in the article instead of the original content of the shortcode.

At this time, the attribute parameters will be parsed and the associative array will be passed to $attr. For example, in the above example, the value of $attr is an associative array as follows:

array( 'title' => '欢迎')

When outputting results, you can directly use the form of $parameter name to output. In the case of the example, the attribute value is output as $title.

6.shortcode_atts

shortcode_atts is a very practical function that can set default values ​​for the attribute parameters you need and delete some unnecessary parameters.

shortcode_atts() contains two parameters $defaults_array and $atts. $attr is the attribute parameter collection. $defaults_array represents the default value of the attribute that needs to be set. For example:

$result = shortcode_atts( array(
 'title' => '新标题',
 'description' => '描述内容'
), $atts );
$attr 依然为

array( 'title' => '欢迎')

The result of $result is

array( 'title' => '新标题', 'description' => '描述标题')

'title' Since there are different values ​​in $defaults_array, 'title' is updated based on this new value, and the value of 'description' is also added. It is worth noting that shortcode_atts() will filter attributes that are not in $defaults_array. If there is an 'ohter' attribute in $attr, then the result of $result will still be the above result, because there is no 'other' in $defaults_array this property. Of course, the value mentioned here is only the default value of the attribute, and the actual output value is still the value filled in when shortcode is called.

7. Further parse attributes and set attribute default values

The

extract() function is used to further parse attributes and set attribute default values. One of its functions is to assign each attribute parameter value to a variable in the form of "$parameter name" and save it (such as $title in the example). It is easy to call. Use this function together with shortcode_atts() to output the results safely. For the specific use of this point, please refer to the example of the first point of this article "1. Function add_shortcode".

In addition, uppercase letters in attribute names will be converted to lowercase letters before being passed to the processing function, so it is recommended to use lowercase letters directly when writing attribute names.

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