Trigger action when new post is insert in wordpres

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

回答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.

回答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.