根据Simple upload field for WordPress通过 Nicolas Kuttler，可以创建自定义上传表单字段。但是，引入的代码只是函数。我想知道如何使用它。

有人可以提供一个工作示例吗？如果代码提供上传文件的功能，那么代码是否属于该页面对我来说并不重要。我希望能够通过管理面板上传文件。

[编辑]

我想上传除图像之外的文件，包括文本文件和 xml。我也想在没有 javascript 的情况下实现它。目前还没有发布有效的答案。 (不过，我很欣赏已发布的信息作为答案。)

提前致谢。

建议sample plugin不允许用户与上传框交互。我附上了下面的截图。

最佳答案

对于想要了解更多关于文件上传的任何人，这里有一个涵盖主要主题和痛点的快速入门。这是在 Linux 机器上使用 WordPress 3.0 编写的，代码只是教授概念的基本概述——我相信这里的一些人可以提供改进实现的建议。
概述您的基本方法

至少有三种方法可以将图像与帖子相关联:使用 post_meta 字段存储图像路径，使用 post_meta 字段存储图像的媒体库 ID(稍后会详细介绍)，或将图像作为附件分配给帖子。此示例将使用 post_meta 字段来存储图像的媒体库 ID。天啊。
多部分编码

默认情况下，WordPress 的创建和编辑表单没有 enctype。如果你想上传一个文件，你需要在表单标签中添加一个“enctype='multipart/form-data'”——否则 $_FILES 集合根本不会被推送。在 WordPress 3.0 中，有一个钩子(Hook)。在某些以前的版本中(不确定细节)，您必须用字符串替换表单标签。

function xxxx_add_edit_form_multipart_encoding() 
{

echo ' enctype="multipart/form-data"';

}
add_action('post_edit_form_tag', 'xxxx_add_edit_form_multipart_encoding');

 // If there is an existing image, show it
    if($existing_image) {

        echo '<div>Attached Image ID: ' . $existing_image . '</div>';

    } 

    echo 'Upload an image: <input type="file" name="xxxx_image" id="xxxx_image" />';

    // See if there's a status message to display (we're using this to show errors during the upload process, though we should probably be using the WP_error class)
    $status_message = get_post_meta($post->ID,'_xxxx_attached_image_upload_feedback', true);

    // Show an error message if there is one
    if($status_message) {

        echo '<div class="upload_status_message">';
            echo $status_message;
        echo '</div>';

    }

    // Put in a hidden flag. This helps differentiate between manual saves and auto-saves (in auto-saves, the file wouldn't be passed).
    echo '<input type="hidden" name="xxxx_manual_save_flag" value="true" />';

}



function xxxx_setup_meta_boxes() {

    // Add the box to a particular custom content type page
    add_meta_box('xxxx_image_box', 'Upload Image', 'xxxx_render_image_attachment_box', 'post', 'normal', 'high');

}
add_action('admin_init','xxxx_setup_meta_boxes');

function xxxx_update_post($post_id, $post) {

    // Get the post type. Since this function will run for ALL post saves (no matter what post type), we need to know this.
    // It's also important to note that the save_post action can runs multiple times on every post save, so you need to check and make sure the
    // post type in the passed object isn't "revision"
    $post_type = $post->post_type;

    // Make sure our flag is in there, otherwise it's an autosave and we should bail.
    if($post_id && isset($_POST['xxxx_manual_save_flag'])) { 

        // Logic to handle specific post types
        switch($post_type) {

            // If this is a post. You can change this case to reflect your custom post slug
            case 'post':

                // HANDLE THE FILE UPLOAD

                // If the upload field has a file in it
                if(isset($_FILES['xxxx_image']) && ($_FILES['xxxx_image']['size'] > 0)) {

                    // Get the type of the uploaded file. This is returned as "type/extension"
                    $arr_file_type = wp_check_filetype(basename($_FILES['xxxx_image']['name']));
                    $uploaded_file_type = $arr_file_type['type'];

                    // Set an array containing a list of acceptable formats
                    $allowed_file_types = array('image/jpg','image/jpeg','image/gif','image/png');

                    // If the uploaded file is the right format
                    if(in_array($uploaded_file_type, $allowed_file_types)) {

                        // Options array for the wp_handle_upload function. 'test_upload' => false
                        $upload_overrides = array( 'test_form' => false ); 

                        // Handle the upload using WP's wp_handle_upload function. Takes the posted file and an options array
                        $uploaded_file = wp_handle_upload($_FILES['xxxx_image'], $upload_overrides);

                        // If the wp_handle_upload call returned a local path for the image
                        if(isset($uploaded_file['file'])) {

                            // The wp_insert_attachment function needs the literal system path, which was passed back from wp_handle_upload
                            $file_name_and_location = $uploaded_file['file'];

                            // Generate a title for the image that'll be used in the media library
                            $file_title_for_media_library = 'your title here';

                            // Set up options array to add this file as an attachment
                            $attachment = array(
                                'post_mime_type' => $uploaded_file_type,
                                'post_title' => 'Uploaded image ' . addslashes($file_title_for_media_library),
                                'post_content' => '',
                                'post_status' => 'inherit'
                            );

                            // Run the wp_insert_attachment function. This adds the file to the media library and generates the thumbnails. If you wanted to attch this image to a post, you could pass the post id as a third param and it'd magically happen.
                            $attach_id = wp_insert_attachment( $attachment, $file_name_and_location );
                            require_once(ABSPATH . "wp-admin" . '/includes/image.php');
                            $attach_data = wp_generate_attachment_metadata( $attach_id, $file_name_and_location );
                            wp_update_attachment_metadata($attach_id,  $attach_data);

                            // Before we update the post meta, trash any previously uploaded image for this post.
                            // You might not want this behavior, depending on how you're using the uploaded images.
                            $existing_uploaded_image = (int) get_post_meta($post_id,'_xxxx_attached_image', true);
                            if(is_numeric($existing_uploaded_image)) {
                                wp_delete_attachment($existing_uploaded_image);
                            }

                            // Now, update the post meta to associate the new image with the post
                            update_post_meta($post_id,'_xxxx_attached_image',$attach_id);

                            // Set the feedback flag to false, since the upload was successful
                            $upload_feedback = false;


                        } else { // wp_handle_upload returned some kind of error. the return does contain error details, so you can use it here if you want.

                            $upload_feedback = 'There was a problem with your upload.';
                            update_post_meta($post_id,'_xxxx_attached_image',$attach_id);

                        }

                    } else { // wrong file type

                        $upload_feedback = 'Please upload only image files (jpg, gif or png).';
                        update_post_meta($post_id,'_xxxx_attached_image',$attach_id);

                    }

                } else { // No file was passed

                    $upload_feedback = false;

                }

                // Update the post meta with any feedback
                update_post_meta($post_id,'_xxxx_attached_image_upload_feedback',$upload_feedback);

            break;

            default:

        } // End switch

    return;

} // End if manual save flag

    return;

}
add_action('save_post','xxxx_update_post',1,2);

<Files ^(*.jpeg|*.jpg|*.png|*.gif)>
order deny,allow
deny from all
</Files>

关于php - WordPress 管理面板中的简单上传表单字段，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/12876047/