Check for update vs new post on save_post action

Question

Is it possible within the save_post action to determine whether it's a new post being created or an existing post being update?

Answer 1

Since WordPress version 3.7. - IIRC - the save_post hook - more information about the hook and its usage at Code Reference: save_post and Codex: save_post - has a third parameter $update which can be used to determine just that.

@param     int               $post_ID     Post ID.
@param     WP_Post     $post          Post object.
@param     bool            $update     Whether this is an existing post being updated or not.

---

Note:

$update is not always true – you can see and test it yourself with below code. It is not well documented though, possibly far from optimally named, and hence creates misleading expectations. Below code can be used for some debugging, play around with when to intercept code execution, because otherwise you won't see the information/messages. I think, the culprit in deceptive behavior is the handling of revisions and auto saves – which could be disabled, but I don't recommend it, and haven't tested it. Not sure if this warrants a Trac Ticket, so I didn't open one, if you think so, please follow the link and do it yourself. Aside from that, as stated in the comments, if you have a specific problem, post a new question.

add_action( 'save_post', 'debug_save_post_update', 10, 3 );
function debug_save_post_update( $ID, $post, $update ) {

  echo '<pre>';
  print_r( $post ); echo '<br>';
  echo '$update == ';
  echo $update ? 'true' : 'false';

  //conditions
  if( ! $update && $post->post_status == "auto-draft" ) {
    // applies to new post
    echo ' && $post->post_status == "auto-draft"';
    //die();
  } else if ( ! $update ) {
    // applies basically to the (auto saved) revision 
    //die();
  } else {
    // applies to updating a published post
    // when there is a revision, which is normally the case, 
    // standard behavior of WordPress, then it is considered 
    // an update, which is where the confusion sets in
    // there are other methods, like checking time or post status
    // depending on your use case it might be more appropriate 
    // to use one of those alternatives 
    //die();
  }

  echo '</pre>';
  //die();
}

Answer 2

The way I perform this check (within a hooked function) is to compare the post date and modified date (in GMT for standardisation)

function check_new_vs_update( $post_id ){
    $myPost        = get_post($post_id);
    $post_created  = new DateTime( $myPost->post_date_gmt );
    $post_modified = new DateTime( $myPost->post_modified_gmt );
    $diff          = $created->diff( $modified );
    $seconds_difference = ((($diff->y * 365.25 + $diff->m * 30 + $diff->d) * 24 + $diff->h) * 60 + $diff->i)*60 + $diff->s;

    if( $seconds_difference <= 1 ){
        // New post
    }else{
        // Updated post
    }
}
add_action('save_post', 'check_new_vs_update' );

This works because even at creation the post has a 'modified' date attached to it, which is exactly the same as the 'created' date, but we allow a variance of 1 second either way in case a second ticks over during the creation of the post.

Answer 3

I ended up just checking for the existence of a custom value prior to setting it. That way, if it's a newly created post the custom value would not yet exist.

function attributes_save_postdata($post_id) {
  if (defined('DOING_AUTOSAVE') && DOING_AUTOSAVE) return;
  if (!wp_verify_nonce($_POST['_attributes_noncename'], plugin_basename(__FILE__))) return;
  if ('page' == $_POST['post_type']) {
    if (!current_user_can('edit_page', $post_id)) return;
  } else {
    if (!current_user_can('edit_post', $post_id)) return;
  }
  $termid = get_post_meta($post_id, '_termid', true);
  if ($termid != '') {
    // it's a new record
    $termid = 'update';
  } else {
    // it's an existing record
  }
  update_post_meta($post_id, '_termid', $termid);
}
add_action('save_post', 'attributes_save_postdata');

Answer 4

Example to ialocin answer with "update" paremeter:

function save_func($ID, $post,$update) {

   if($update == false) {
     // do something if its first time publish
   } else {
     // Do something if its update
   }
}

add_action( 'save_post', 'save_func', 10, 3 );

Answer 5

You can use pre_post_update action hook for the update code and save_post for the new post code. It works before a post is updated.

Answer 6

As Darshan Thanki hinted (and Stephen Harris further elaborated), you can use pre_post_update to your advantage.

global $___new_post;
$___new_post = true;

add_action(
  'pre_post_update',
  function() {
    global $___new_post;
    $___new_post = false;
  },
  0
);

function is_new_post() {
  global $___new_post;
  return $___new_post;
}

The reason why I used globals is because function is_new_post() use ( &$new_post ) is not valid in PHP (shocking...) so pulling in that variable into the function scope doesn't work -- hence the global.

Note that this can really only reliably be used within/after the save_post event (which is usually sufficient, at least for what we're doing with it).

Answer 7

I have just encountered the save_post about new and update. After reading the source code to understand the flow. I found that the following method might be useful. Since it is not yet mentioned before. See if it is useful to anyone. (The test is Core 5.3.3)

The Post creation flow is approximately:

1. After pressing Add New (Post)
2. $post = get_default_post_to_edit( $post_type, true ); will be called where
3. get_default_post_to_edit() receive argument $create_in_db = true
4. so wp_insert_post() is immediately being called, auto-draft post is being created, even it is not saved, every time clicking Add New, an auto-draft is created
5. $update is always true for Publish. So when Publish a new post, it is true.

By comparing the $_POST object for new post and update post or republish post, the prominent difference is value _wp_http_referer, the new post is /wp-admin/post-new.php

Assumption: assumed the post is published/added from UI. If it is done by other mechanism, custom code, the checking is needed to adjust.

add_action( 'save_post', 'test_save_post_check', 0, 3 );
function test_save_post_check( $post_ID, $post, $update ) {
    // other tests + this
    // checking the 'post-new' position from the '_wp_http_referer'
    if( strpos( wp_get_raw_referer(), 'post-new' ) > 0 ) {
        // new
    } else {
        // update
    }
}

Answer 8

When save_post is triggered, all information about that post is already available, so in theory you could use

function f4553265_check_post() {

    if (!get_posts($post_id)) {
    // if this is a new post get_posts($post_id) should return null
    } else {
    // $post_id already exists on the database
    }
}
add_action('save_post','f4553265_check_post');

this is untested, though. =)

Answer 9

Another approach that uses a built-in function and no addition to the database would involve get_post_status().

$post_status = get_post_status();
if ( $post_status != 'draft' ) {
    //draft
} else { 
    //not a draft: can be published, pending, etc. 
}

Note however that it might not be appropriate if you plan to later set the status back to "draft" – your instructions would be repeated the next time you will update the post. Depending on the context, you might want to consider the various strings that can be returned by get_post_status() to build a more appropriate scenario.

See Codex for get_post_status() and Post Status

Possible values are:

• 'publish' - A published post or page
• 'pending' - post is pending review
• 'draft' - a post in draft status
• 'auto-draft' - a newly created post, with no content
• 'future' - a post to publish in the future
• 'private' - not visible to users who are not logged in
• 'inherit' - a revision. see get_children.
• 'trash' - post is in trashbin. added with Version 2.9.

Answer 10

Since the $update param is useless, this is the fastest way I tested:

function wpse48678_check_is_post_new($post_id, $post, $update)
{
    if (false !== strpos($_POST['_wp_http_referer'], 'post-new.php')) {
        return true; // Or do something else.
    } else {
        return false; // Or do something else.
    }
}
add_action('save_post_{$post_type}', 'wpse48678_check_is_post_new', 10, 3);