wordpress php post/redirect/get

Question

I build some code to import csv file to MySQL database but run into form resubmission problem( refreshing the page, upload the file again). I am trying to use post/redirect/get pattern to solve this problem but in WordPress it gets kind of tricky since redirect is working correctly.

<?php
/***update csv file ***/

if(isset($_POST["submit"])) //if submit button is pressed 
{
  if($_FILES['file']['name']) //if file exists
  {
    $filename=explode('.', $_FILES['file']['name']);//seperate file into filename and csv
    if($filename[1]=='csv'){  //if file format is csv
      $handle= fopen($_FILES['file']['tmp_name'], "r");
      while($data=fgetcsv($handle)){
        $sql="INSERT INTO val_in (xxxx,xxxx,xxxx,xxxx,xxxx,xxxx) VALUES(?,?,?,?,?,?)";
        //prepared statement 
        $stmt=mysqli_stmt_init($conn);
        if(!mysqli_stmt_prepare($stmt,$sql)){
          echo "SQL prepared statement error";
        }


        else{
          echo gettype($data[0]);
          mysqli_stmt_bind_param($stmt,"issddi",$data[0],$data[1],$data[2],$data[3],$data[4],$data[5]);
          mysqli_stmt_execute($stmt);
        }
      }
      fclose($handle);
        print "import done";
    }
    else{
      echo "Incorrect file format. Please select a CSV file. ";
    }
  }    
}
<form method='POST' enctype='multipart/form-data'>

       <div align="center">  
          <label>Import CSV File:</label>
          <input type="file" name="file" id="csvFile1" />
          <input type="submit" name="submit" value="Import" class="btn btn-info" />
         </div>
    </form>  

I tried a few ways to re-direct but haven't found a way to get things working:

wp_redirect( site_url(),303 );
header("Location: http://localhost:8888/dm_toolkit/wordpress/validation-data-input/?file=val_in_test.csv&submit=Import");
 header("Location: xxx.php");
    wp_redirect(get_permalink($post->ID) . '?success=true');

none of these are working. In addition, if I put in a "exit" or "die()" in the end, it goes to a page that does not have any of my existing content.

Answer 1

you can attach a action to template redirect hook. There you can check if your post request is set and do your procession and then do redirection.

add_action('template_redirect', 'handle_post_csv_request');

function handle_post_csv_request() {

if (isset($_POST["submit"])) { //if submit button is pressed 
    if ($_FILES['file']['name']) { //if file exists
        //your code goes here

        wp_redirect(site_url(), 303);
    }
}

}