submitting form via admin-ajax.php returns 0

Question

Trying to:

Submit form using admin-ajax.php to update post data from 'draft' status to 'publish' status and add custom meta field for filter type.

Form contents:

<form action="<?php echo admin_url( 'admin-ajax.php' ) ?>" method="post">

        <?php wp_nonce_field( 'submit_filter', 'my_filter_nonce' ); ?>

        <div class="small-6 medium-3 large-3 columns">
            <div class="card">
                <img src="<?php echo get_the_post_thumbnail_url( $posts[0]->ID, 'thumbnail' ); ?>" class="" id="normal">
                    <div class="card-section">
                        <input type="submit" value="No Filter" name="normal">
                    </div>
            </div>
        </div>
</form>

Form action:

// process form actions
add_action( 'wp_ajax_nopriv_submit_filter', 'my_submission_filter' );
add_action( 'wp_ajax_submit_filter', 'my_submission_filter' );


function my_submission_filter() {

    $postid = get_the_ID();
    $post_data = array(
          'ID'              => $postid,
          'post_status'     => 'publish'

     );


// add filter meta data
add_post_meta($postid, 'filter', $_POST['filter']); 

// Update the post into the database
wp_update_post( $my_post );

// redirect back to site to see post
wp_redirect( site_url());

die();

}

Results:

Blank page with a "0" in the top right corner and no updates to post.

Would like:

Help making this work :)

Answer 1

You don't set an action in your form, so nothing is executed.

Add a hidden field with action to the form:

<input type="hidden" value="submit_filter" name="action">

Also note that this:

$postid = get_the_ID();

won't work. This is a new request, so there is no post to get the ID from. You have to pass this with your form data as well.

Answer 2

admin-ajax.php is intended for AJAX requests, but this is not an AJAX request, it's a form submission! Perhaps if this was a javascript based submission it would be appropriate, but, you should avoid the quirks of Admin AJAX and make a standard form handler.

When submitting a form, submit it to the same page the form is located on. This way the form handling and display are next to each other and validation becomes a lot easier to display.

For example:

if ( ! empty( $_POST['submission'] )) {
    // the form was submitted!

    $success = false;
    // fetch the parameters, do some validation, etc

    // ... handle the form submission

    // all done, if successful say so else load the form
    if ( true === $success ) {
        get_template_part( 'theform', 'success' ); // theform-success.php
    } else {
        // show the form again with whatever validation errors there were
        get_template_part( 'theform' ); 
    }
} else {
    // the form was not submitted, DISPLAY THE FORM!!! First page
    get_template_part( 'theform' );
}

theform.php will contain your form, and for the action of the form you'll just leave it empty, e.g. <form method="POST" action="">

Handling Multiple Pages

You can add a hidden field named page, and then load different templates depending on its value, and process when on the final page + 1. There is something to keep in mind though, values from page 1 won't be there when you submit page 2, so you need to carry them over in hidden fields.

Answer 3

You are not submitting your data with AJAX, so there is no need to use admin-ajax.php and the wp_ajax hook. Instead, you need the admin_post hook.

You need to make a few changes to your code in order to make it work. First, change your form action to <?php echo esc_url( admin_url('admin-post.php') ); ?> and add a hidden action field at the end of your form <input type="hidden" name="action" value="submit_filter">.

This way, anytime a request is send to WordPress and the action parameter is set to "submit_filter", the hook admin_post_submit_filter will be executed.

This is how your form code should look:

<form action="<?php echo esc_url( admin_url('admin-post.php') ); ?>" method="post">
   <?php wp_nonce_field( 'submit_filter', 'my_filter_nonce' ); ?>
   <div class="small-6 medium-3 large-3 columns">
      <div class="card">
          <img src="<?php echo get_the_post_thumbnail_url( $posts[0]->ID, 'thumbnail' ); ?>" class="" id="normal">
          <div class="card-section">
              <input type="submit" value="No Filter" name="normal">
          </div>
      </div>
    </div>
    <input type="hidden" name="action" value="submit_filter">
</form>

And the function code to process your request:

add_action( 'admin_post_nopriv_submit_filter', 'my_submission_filter' );
add_action( 'admin_post_submit_filter', 'my_submission_filter' );

function my_submission_filter() {
  $postid = get_the_ID();

  $post_data = array(
    'ID'              => $postid,
    'post_status'     => 'publish'
  );

  add_post_meta($postid, 'filter', $_POST['filter']); 
  wp_update_post( $my_post );

  wp_redirect( site_url());
}

It's also good to check for errors using is_wp_error

https://codex.wordpress.org/Plugin_API/Action_Reference/admin_post_(action) https://codex.wordpress.org/Function_Reference/is_wp_error