自定义页面表单动作wordpress管理员

Question

我在functions.php的wordpress admin中添加了一个自定义页面。并在同一页面上添加表单并尝试执行操作。

在这里你可以看到实际发生的事情，这里是我的网站goo.gl/jLfsDo的后端网址。用户名是admin，密码是testwooc ++。在左侧菜单栏上，标题为“上载COD文件”的管理菜单栏。我在当前主题的functions.php上添加了它，需要在同一页面添加动作结果。但它不起作用。

/*******************/
/*Form starts here*/
/*****************/
<div style="width:750px;">
<h1><span style="position:relative;top:-7px">Upload COD file</span></h1>
<form action="<?php the_permalink(); ?>" method="post" enctype="multipart/form-data">
  Please choose a file: <input type="file" name="uploadFile"><br>
  <input type="submit" value="Upload File">
</form> 




/*Form action starts here */
<?php 
  if(isset($_POST['submit'])) {
    $target_dir =  basename( $_FILES["uploadFile"]["name"]);
    $uploadOk=1;
    $contents2 = "";
    if (move_uploaded_file($_FILES["uploadFile"]["tmp_name"], $target_dir)) {
        echo "The file ". basename( $_FILES["uploadFile"]["name"]). " has been uploaded.";

      $CSVfp = fopen($target_dir, "r");
      if($CSVfp !== FALSE) 
       while(!feof($CSVfp)) {
       $data = fgetcsv($CSVfp, 3000, ",");
       $contents2 .=  $data[3]; 
       $var_str = var_export($contents2, true);
       $file = 'new_file.txt';
       $var_str = str_replace("'",",",$var_str);
       // $var_str2 = str_replace(" ",",",$var_str);
       // $var_str3 = str_replace(",,",",",$var_str2);
       $var_str3 = ltrim($var_str,"Pin,");
       $var_str3 = implode(",", str_split($var_str3, 6))." ";
       $var_str4 = str_replace(",,","",$var_str3);
       file_put_contents($file, $var_str4);
    } 

    }
    else {
        echo "Sorry, there was an error uploading your file.";
    }

?> 
<form method="get" action="new_file.txt">
<button type="submit">Download!</button>
</form>
<?php
   }

?>