Trigger action when new post is insert in wordpress - wordpress

Question

My question is,
Is there any filter or action that trigger when new post is insert in database..?
The reason behind it is I want to add key in post meta when new post is insert from admin side.
I got Action called "save_post" but after refer link .This action trigger in created and update post.
but I only want to add meta key when post is created not at update time

Answer 1

You can use wp_insert_post so you will get post_id as soon as post inserted and you can then use that to add meta_key.
If you are not using wp_insert_post and want to use action then you can simply put below code :
if ( wp_is_post_revision( $post_id ) )
return;
which means that if you are updating the post, then it will return back from function.
EDITED
Method-1 to achieve it.
You can simply check with the get_post method that post is there or not.something like below:
add_action('save_post', 'check_for_post_in_database');
function check_for_post_in_database($post_id) {
//check if the post is in the database or not with get_post( $post_id ) == null
if( get_post( $post_id ) == null ) {
//your code to add meta
}
}
//You can do same thing with publish_post
Method-2 to achieve it.
add_action('publish_post', 'check_for_meta_in_database');
function check_for_meta_in_database($post_id) {
global $wpdb;
$your_meta = get_post_meta($post_id, 'meta_key', true);
if( empty( $your_meta ) && ! wp_is_post_revision( $post_id ) ) {
update_post_meta($post_id, 'meta_key', 'meta_value');
}
}
But as you said there are many meta there, this method will be bit long.
Method-3 to achieve it.
You can do as rnevius suggested which is the one even I would opt. Its like :
add_action( 'transition_post_status', 'check_transition_and_then_add_meta', 10, 3 );
function check_transition_and_then_add_meta( $new_status, $old_status, $post ) {
if ( ( 'draft' === $old_status || 'auto-draft' === $old_status ) && $new_status === 'publish' ) {
add_post_meta($post->ID, 'your_meta_key', 'your_meta_value');
}
}
or else you can do it with draft_to_publish like:
//as rnevius suggested {$old_status}_to_{$new_status}
add_action( 'draft_to_publish', 'add_meta_when_status_change' );
function add_meta_when_status_change() {
add_post_meta($post->ID, 'your_meta_key', 'your_meta_value');
}
You can refer codex for more information about post transition.

Answer 2

You're looking for draft_to_publish.
An {old_status}_to_{new_status} action will execute when a post transitions from {old_status} to {new_status}. The action is accompanied by the $post object.