selected()
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概述
selected() 是 WordPress 核心函数，用于输出 HTML 的 selected 属性。它通过比较两个参数，若相同则标记为选中状态，常用于生成下拉菜单选项。
关键要点
- 函数原型：selected( $selected, $current = true, $display = true )，返回字符串或直接输出。
- 参数说明：$selected 为必需值，用于比较；$current 可选，默认为 true；$display 控制是否回显，默认为 true。
- 内部实现：调用 __checked_selected_helper() 辅助函数，处理 selected、checked、disabled 和 readonly 属性。
- 应用场景：广泛用于 WordPress 后台和前端，如评论类型下拉、语言选择器、页面模板下拉等。
代码示例
// 示例：在循环中生成下拉选项，使用 selected() 标记当前选中项
foreach ( $posts as $post ) {
echo '<option value="' . esc_attr( $post->ID ) . '"'
. selected( $selected_id, $post->ID, false ) . '>'
. esc_html( $post->post_title ) . '</option>';
}注意事项
- 当在 sprintf 或字符串拼接中使用时，需将 $display 参数设为 false 以返回字符串而非直接输出。
- 确保参数类型匹配，避免比较错误；函数基于值相等性判断，不进行类型转换。
原文内容
Outputs the HTML selected attribute.
Description
Compares the first two arguments and if identical marks as selected.
Parameters
$selectedmixedrequired-
One of the values to compare.
$currentmixedoptional-
The other value to compare if not just true.
Default:
true $displaybooloptional-
Whether to echo or just return the string.
Default:
true
Source
function selected( $selected, $current = true, $display = true ) {
return __checked_selected_helper( $selected, $current, $display, 'selected' );
}
Changelog
| Version | Description |
|---|---|
| 1.0.0 | Introduced. |
Skip to note 4 content
Codex
Example
<!-- Testing the values with if() --> <select name="options[foo]"> <option value="1" <?php if ( $options['foo'] == 1 ) echo 'selected="selected"'; ?>>1</option> <option value="2" <?php if ( $options['foo'] == 2 ) echo 'selected="selected"'; ?>>2</option> <option value="3" <?php if ( $options['foo'] == 3 ) echo 'selected="selected"'; ?>>3</option> </select> <!-- Using selected() instead --> <select name="options[foo]"> <option value="1" <?php selected( $options['foo'], 1 ); ?>>1</option> <option value="2" <?php selected( $options['foo'], 2 ); ?>>2</option> <option value="3" <?php selected( $options['foo'], 3 ); ?>>3</option> </select>Skip to note 5 content
tradesouthwest
Selected Using foreach loop
/** * Demonstration uses all cpt posts in a dropdown field to select * a featured listings to callback in a function */ function wporg_wpselected_featured_listing_cb() { $post_type = 'wpselected_post'; $options = get_option( 'wpselected_lists' ); // select(ed)_id will be a custom option outside of this function. $wpselected_select_id = $options['wpselected_featured_listing']; // Avoid ending up with no string value by setting a default value if ( '' === $wpselected_select_id ) { $wpselected_select_id = 0; } /** * Sets up a list of cpt posts to do foreach with * @param $label string Optional */ $post_type_object = get_post_type_object( $post_type ); $label = $post_type_object->label; $posts = get_posts( array( 'post_type' => $post_type, 'post_status' => 'publish', 'suppress_filters' => false, 'posts_per_page' => -1 ) ); ?> <label class="olmin"></label> <select name="wpselected_lists[wpselected_featured_listing]"> <option value="0"></option> ID ) . '"' . selected( $wpselected_select_id, $post->ID, false ) . '>' . esc_html__( $post->post_title, 'wpselected' ) . '</option>'; } echo '</select>'; }Ideally you may choose to use
ob_start()andob_get_clean()to avoid any HTML glitches on front.Skip to note 6 content
Chigozie Orunta
If you’re going to use this in a sprintf or string function, make sure you turn the echo parameter to false (so it returns a string instead of outputting directly) like so:
// Defined options define( 'OPTIONS', array( 1 => 'A', 2 => 'B', 3 => 'C', 4 => 'D' ) ); // My option $my_option = 1; // OR fetched option value // Get HTML options $html_options = ''; foreach ( OPTIONS as $key => $value ) { $html_options .= sprintf( '<option value="%1$s" %3$s>%2$s</option>', esc_attr( $key ), esc_html( $value ), <strong>selected( $my_option, esc_attr( $key ), false )</strong> ); } // Display Select element or tag echo '<select>' . $html_options . '</select>';