javascript - jquery和ajax上传图片两次

Question

我有一个通过 ajax 上传图像的 jQuery 脚本，我注意到由于某种原因，它上传图像两次。一旦在ajax步骤中，它们作为隐藏值嵌入到表单中，然后当有人单击提交表单时，上传过程会再次开始，而实际上不应该开始，因为图像已经在服务器上。我看到它是因为我使用 Chrome，当我点击提交时，它在左下角再次显示“正在上传(19%)..”等。这不是我的脚本，而且我对 jQuery 很不擅长，所以我不知道出了什么问题。这里有什么明显的东西可以让它在提交时再次上传吗？

function media_sync(form_name, media_type, file_path, file_url, file_embed, nb_uploads, max_uploads, upload_id) {
   var radio_buttons = [];
   for (var i = 0; i < form_name.length; i++) {
      if (form_name.elements[i].type == 'radio' && form_name.elements[i].checked == true) {
         radio_buttons[form_name.elements[i].name] = form_name.elements[i].value;
      }
   }

   var jsHttp = new JsHttpRequest();
   var xmlHttp = GetXmlHttpObject();

   if (jsHttp == null) {
      alert("Browser does not support HTTP Request");
      return;
   }

   var media_name = '';
   switch (media_type) {
      case 1:
         media_name = 'ad_image';
         break;
      case 2:
         media_name = 'ad_video';
         break;
      case 3:
         media_name = 'ad_dd';
         break;
   }

   var media_box_name = 'display_media_boxes_' + media_name;

   file_embed = base64Encode(file_embed);
   var url = relative_path + 'file_upload.php';
   var action = url + '?do=add&media_type=' + media_type + '&file_url=' + file_url +
           '&file_embed=' + file_embed + '&nb_uploads=' + nb_uploads + '&upload_id=' + upload_id;

   var thumbnail_div = document.getElementById('display_media_boxes_' + media_name);
   var new_content = document.createElement('div');

   if (file_embed != '') {
      xmlHttp.onreadystatechange = function() {
         if (xmlHttp.readyState == 4) {
            var response = xmlHttp.responseText;

            var results = response.split('|');

            if (results[5] != '') {
               alert(results[5]);
            }
            else {
               new_content.innerHTML = results[3];

               while (new_content.firstChild) {
                  thumbnail_div.appendChild(new_content.firstChild);
               }

               var hidden_div = document.getElementById('hidden_media_boxes');
               var hidden_content = document.createElement('div');
               hidden_content.innerHTML = '<input type="hidden" name="' + results[1] + '[]" id="hidden_' + results[2] + '" value="' + results[4] + '">';

               while (hidden_content.firstChild) {
                  hidden_div.appendChild(hidden_content.firstChild);
               }
               nb_uploads++;
            }

            document.getElementById('item_file_url_' + media_type).value = '';
            document.getElementById('item_file_embed_' + media_type).value = '';

            if (nb_uploads >= max_uploads) {
               document.getElementById('btn_upload_' + media_type).disabled = true;
               document.getElementById('item_file_upload_' + media_type).disabled = true;
               document.getElementById('item_file_url_' + media_type).disabled = true;
               document.getElementById('item_file_embed_' + media_type).disabled = true;
            }
            document.getElementById('nb_uploads_' + media_type).value = nb_uploads;
         }
      };
      xmlHttp.open("POST", action, true);
      xmlHttp.send(null);
   }
   else {
      jQuery.blockUI({ 
          message: $('#uploading_image'), 
          css: { 
              top:  '20%', 
              left: ($(window).width() - 400) /2 + 'px', 
              width: '400px'
          } 
      });


      var image_loading = document.createElement('div');
      image_loading.innerHTML = '';
      thumbnail_div.appendChild(image_loading);

      jsHttp.onreadystatechange = function() {
         if (jsHttp.readyState == 4) {
            var response = jsHttp.responseText;

            var results = response.split('|');

            if (results[5] != '') {
               alert(results[5]);
               thumbnail_div.removeChild(image_loading);
               setTimeout(jQuery.unblockUI, 500);
            }
            else {
               new_content.innerHTML = results[3];

               while (new_content.firstChild) {
                  thumbnail_div.replaceChild(new_content.firstChild, image_loading);
               }
               setTimeout(jQuery.unblockUI, 500);

               var hidden_div = document.getElementById('hidden_media_boxes');
               var hidden_content = document.createElement('div');
               hidden_content.innerHTML = '<input type="hidden" name="' + results[1] + '[]" id="hidden_' + results[2] + '" value="' + results[4] + '">';

               while (hidden_content.firstChild) {
                  hidden_div.appendChild(hidden_content.firstChild);
               }
               nb_uploads++;
            }

            document.getElementById('item_file_url_' + media_type).value = '';
            document.getElementById('item_file_embed_' + media_type).value = '';

            if (nb_uploads >= max_uploads) {
               document.getElementById('btn_upload_' + media_type).disabled = true;
               document.getElementById('item_file_upload_' + media_type).disabled = true;
               document.getElementById('item_file_url_' + media_type).disabled = true;
               document.getElementById('item_file_embed_' + media_type).disabled = true;
            }
            document.getElementById('nb_uploads_' + media_type).value = nb_uploads;

            for (var i = 0; i < form_name.length; i++) {
               if (form_name.elements[i].type == 'radio' && radio_buttons[form_name.elements[i].name] == form_name.elements[i].value) {
                  form_name.elements[i].checked = true;
               }
            }
         }
      };

      jsHttp.open("POST", action, true);
      jsHttp.send({file: file_path});
   }
   jQuery('#upload_form').attr('target', '_self');
}

HTML 表单非常基本，有一堆隐藏值字段，它们只是变量和图像上传部分，如下所示:

<form id="upload_form" action="new.php" method="post" enctype="multipart/form-data" name="ad_create_form">

<input class="upload_button" type="file" name="item_file_upload_1" id="item_file_upload_1"
         onchange="media_sync(ad_create_form, 1, 
         this.form.item_file_upload_1, 
         document.getElementById('item_file_url_1').value, 
         document.getElementById('item_file_embed_1').value, 
         document.getElementById('nb_uploads_1').value, 
         5, 
         '000000015');"  />

<input name="finish" id="finish" value="Add" type="submit" class="btn">

</form>

如果有人能找出导致此问题的原因，非常感谢! :)

Answer 1

您有一个“onchange”，它会触发 media_sync 函数，然后运行 ​​Ajax 来发布数据。然后您还可以让表单本身提交数据。这就是为什么它要上传两次，一次用于 Ajax，一次用于表单提交。您需要选择其中之一而不是同时使用两者。我不确定您想要使用哪一个，因为这取决于您希望页面如何工作。我的猜测是，Ajax 就足够了，因此删除表单提交(因为表单中唯一的内容就是一个输入)。