我將實現一個插件，可以爲匿名用戶（從前端）上傳（兩個）圖像。因此，圖像的縮略圖也應該被顯示。因此，我創建了具有兩個自定義（圖像）字段的自定義帖子類型。wordpress圖像以編程方式上傳到自定義字段
現在我想實現圖像的上傳。我已經做了一些研究，因此我發現wordpress函數「wp_insert_attachment」來保存文件。但是 - 現在如何將圖像保存到自定義字段（在上傳這些圖像時使用縮略圖）？
任何人都可以幫助我嗎？
謝謝！
對於任何想要了解更多關於文件上傳的人來說，這裏有一個快速入門，涵蓋主要主題和難點。這是使用WordPress 3.0在Linux上編寫的，代碼只是教授這些概念的基本概述。我相信這裏的一些人可以提供改進實施建議。
勾勒出你的根本方法
至少有三種方式將圖像與職位相關聯：使用post_meta字段來存儲圖像路徑，使用post_meta字段來存儲圖像的媒體庫ID（更多以後），或將圖像作爲附件分配給帖子。此示例將使用post_meta字段來存儲圖像的媒體庫ID。因人而異。
多部分編碼
默認情況下，WordPress的創建&編輯表單沒有加密類型。如果你想上傳一個文件，你需要在表單標籤中添加一個「enctype ='multipart/form-data'」，否則$ _FILES集合根本不會被推送。在WordPress 3.0中，有一個鉤子。在一些以前的版本中（不確定具體情況），你必須將字符串替換爲表單標籤。
function xxxx_add_edit_form_multipart_encoding() {
echo ' enctype="multipart/form-data"';
}
add_action('post_edit_form_tag', 'xxxx_add_edit_form_multipart_encoding');
創建元盒，並上傳現場 我不會走多遠進入創造元盒，因爲大多數的你可能已經知道該怎麼做，但我只想說，你只需要一個帶有文件字段的簡單元框。在下面的示例中，我包含了一些代碼來查找現有圖像，並在存在的情況下顯示它。我還包括一些簡單的錯誤/反饋功能，可以使用post_meta字段傳遞錯誤。您需要將其更改爲使用WP_Error類...它僅用於演示。
function xxxx_render_image_attachment_box($post) {
// See if there's an existing image. (We're associating images with posts by saving the image's 'attachment id' as a post meta value)
// Incidentally, this is also how you'd find any uploaded files for display on the frontend.
$existing_image_id = get_post_meta($post->ID,'_xxxx_attached_image', true);
if(is_numeric($existing_image_id)) {
echo '<div>';
$arr_existing_image = wp_get_attachment_image_src($existing_image_id, 'large');
$existing_image_url = $arr_existing_image[0];
echo '<img src="' . $existing_image_url . '" />';
echo '</div>';
}
// If there is an existing image, show it
if($existing_image_id) {
echo '<div>Attached Image ID: ' . $existing_image_id . '</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 $status_message;
echo '</div>';
}
// Put in a hidden flag. This helps differentiate between manual saves and auto-saves (in auto-saves, the file wouldn't be passed).
echo '<input type="hidden" name="xxxx_manual_save_flag" value="true" />';
}
function xxxx_setup_meta_boxes() {
// Add the box to a particular custom content type page
add_meta_box('xxxx_image_box', 'Upload Image', 'xxxx_render_image_attachment_box', 'post', 'normal', 'high');
}
add_action('admin_init','xxxx_setup_meta_boxes');
處理文件上傳
這是一個大的 - 通過鉤住save_post行動實際處理文件上傳。我在下面列出了大量註釋的功能，但我想說明它使用了兩個關鍵的WordPress功能：
wp_handle_upload（）做的，以及所有的魔法，處理上傳。您只需將它傳遞給$ _FILES數組中的字段引用以及一系列選項（不要太擔心這些 - 您需要設置的唯一重要信息是test_form = false。請相信我）。但是，此功能不會將上傳的文件添加到媒體庫。它只是上傳並返回新文件的路徑（並且，也是，完整的URL也是如此）。如果有問題，它會返回一個錯誤。
wp_insert_attachment（）將圖像添加到媒體庫，並生成所有適當的縮略圖。您只需向它剛剛上傳的文件傳遞一組選項（標題，發佈狀態等）和LOCAL路徑（而不是URL）即可。將圖像放入媒體庫的好處是，您可以稍後通過調用wp_delete_attachment並將其項目的媒體庫ID（我在下面的函數中進行處理）傳遞給它，從而輕鬆刪除所有文件。使用此功能，您還需要使用wp_generate_attachment_metadata（）和wp_update_attachment_metadata（），它們完全符合您的期望 - 爲媒體項目生成元數據。
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);
權限，所有權和安全
如果你有麻煩上傳，它可能有操作權限。我不是服務器配置方面的專家，所以如果這部分不合適，請糾正我。
首先，確保您的wp-content/uploads文件夾存在，並且歸屬於apache：apache。如果是這樣，你應該能夠將權限設置爲744，並且所有內容都可以正常工作。所有權非常重要 - 即使設置777的燙髮有時也無濟於事，如果該目錄沒有正確擁有。
您還應該考慮限制使用htaccess文件上傳和執行的文件類型。這可以防止人們上傳不是圖像的文件，也不會執行僞裝成圖像的腳本。你應該谷歌這個更權威的信息，但你可以這樣做簡單的文件類型限制：