Vérifiez si le titre du message existe, insérez le message dans le cas contraire, ajoutez un numéro incrémentiel au méta si tel est le cas

J'ai déjà une fonction où un utilisateur soumet un formulaire et crée un message personnalisé ...

<?php $postTitle = $_POST['post_title'];
$submit = $_POST['submit'];

if(isset($submit)){

    global $user_ID;

    $new_post = array(
        'post_title' => $postTitle,
        'post_content' => '',
        'post_status' => 'publish',
        'post_date' => date('Y-m-d H:i:s'),
        'post_author' => '',
        'post_type' => 'stuff',
        'post_category' => array(0)
    );

    $post_id = wp_insert_post($new_post);
add_post_meta($post_id, 'times', '1');

}

Je veux vérifier si le titre de la publication personnalisée existe, puis si ce n'est PAS le cas, continuer et créer la publication avec un # 1 dans le champ méta, et si elle existe, ajouter simplement 1 au champ méta

Cela nécessiterait une requête.

Alors, construisant sur votre code:

<?php
$postTitle = $_POST['post_title'];
$submit = $_POST['submit'];

if(isset($submit)){

    global $user_ID, $wpdb;

    $query = $wpdb->prepare(
        'SELECT ID FROM ' . $wpdb->posts . '
        WHERE post_title = %s
        AND post_type = \'stuff\'',
        $postTitle
    );
    $wpdb->query( $query );

    if ( $wpdb->num_rows ) {
        $post_id = $wpdb->get_var( $query );
        $meta = get_post_meta( $post_id, 'times', TRUE );
        $meta++;
        update_post_meta( $post_id, 'times', $meta );
    } else {
        $new_post = array(
            'post_title' => $postTitle,
            'post_content' => '',
            'post_status' => 'publish',
            'post_date' => date('Y-m-d H:i:s'),
            'post_author' => '',
            'post_type' => 'stuff',
            'post_category' => array(0)
        );

        $post_id = wp_insert_post($new_post);
        add_post_meta($post_id, 'times', '1');
    }
}

Devrait le faire

Une méthode plus mise à jour peut utiliser la post_exists()fonction comme ceci:

if( isset( $_POST['submit'] ) ){

   $post_title = sanitize_title( $_POST['post_title'] );

   $new_post = array(
       'post_title' => $post_title,
       'post_content' => '',
       'post_status' => 'publish',
       'post_date' => date('Y-m-d H:i:s'),
       'post_author' => '',
       'post_type' => 'stuff',
       'post_category' => array(0)
   );

   $post_id = post_exists( $post_title ) or wp_insert_post( $new_post );

   update_post_meta( $post_id, 'times', '1' );

}

Vous pouvez utiliser la fonction get_page_by_title () de WordPress:

<?php $postTitle = $_POST['post_title'];
$submit = $_POST['submit'];


if(isset($submit)){
    $customPost = get_page_by_title($postTitle, OBJECT, 'stuff');

    if(!is_null($customPost)) {
       $meta = get_post_meta($customPost->ID, 'times', true);
       $meta++;
       update_post_meta($customPost->ID, 'times', $meta);

       return
    }

    global $user_ID;

    $new_post = array(
        'post_title' => $postTitle,
        'post_content' => '',
        'post_status' => 'publish',
        'post_date' => date('Y-m-d H:i:s'),
        'post_author' => '',
        'post_type' => 'stuff',
        'post_category' => array(0)
    );

    $post_id = wp_insert_post($new_post);
    add_post_meta($post_id, 'times', '1');

}

@Tim Hallman belle réponse. Utilisez la fonction post_exists () pour vérifier si le post existe ou non. Plus de détails sur https://developer.wordpress.org/reference/

Vous pouvez le faire par ID

$post_title = "This Awesome Title";
$post_content = "My content of something cool.";
$post_status = "publish"; //publish, draft, etc
$post_type = "page" // or whatever post type desired

/* Attempt to find post id by post name if it exists */
$found_post_title = get_page_by_title( $post_title, OBJECT, $post_type );
$found_post_id = $found_post_title->ID;

/**********************************************************
** Check If Page does not exist, if true, create a new post 
************************************************************/
if ( FALSE === get_post_status( $found_post_id ) ): 

      $post_args = array(
        'post_title' => $post_title,
        'post_type' => $post_type,
        'post_content'=> $post_content,
        'post_status'  => $post_status,
        //'post_author'  => get_current_user_id(),

        /* If you have meta fields to enter data into */ 
        'meta_input'   => array(
            'meta_key1' => 'my value',
            'meta_key2' => 'my other value',
        ),
      );      


      /* Add a new wp post into db, return it's post id */
      $returned_post_id = wp_insert_post( $post_args );  

      /* Update page template only if using "page" as the post_type */ 
      update_post_meta( $returned_post_id, '_wp_page_template', 'my-page-template.php' ); 

      /* Add values into meta fields. Work with ACF CUSTOM FIELDS!! */
      $field_key = "My_Field_KEY";
      $value = "my custom value";
      update_field( $field_key, $value, $returned_post_id );

      $field_key = "My_Other_Field_KEY";
      $value = "my other custom value";
      update_field( $field_key, $value, $returned_post_id );

      /* Save a checkbox or select value */
      // $field_key = "My_Field_KEY";
      // $value = array("red", "blue", "yellow");
      // update_field( $field_key, $value, $returned_post_id );

      /* Save to a repeater field value */
      // $field_key = "My_Field_KEY";
      // $value = array(
      //   array(
      //     "ss_name" => "Foo",
      //     "ss_type" => "Bar"
      //   )
      // );
      // update_field( $field_key, $value, $returned_post_id );

      /* Echo a response! */
      echo "<span class='pg-new'><strong>". $post_title . " Created!</strong></span><br>";
      echo "<a href='".esc_url( get_permalink($returned_post_id) )."' target='_Blank'>". $post_title . "</a><p>";


else:        
/***************************
** IF POST EXISTS, update it 
****************************/

      /* Update post */
      $update_post_args = array(
        'ID'           => $found_post_id,
        'post_title'   => $post_title,
        'post_content' => $post_content,
      );

      /* Update the post into the database */
      wp_update_post( $update_post_args );

      /* Update values into meta fields */
      $field_key = "My_Field_KEY";
      $value = "my custom value";
      update_field( $field_key, $value, $found_post_id );

      $field_key = "My_Other_Field_KEY";
      $value = "my other custom value";
      update_field( $field_key, $value, $found_post_id );

      /* Echo a response! */
      echo "<span class='pg-update'><strong>". $post_title . " Updated!</strong></span><br>"; 
      echo "<a href='".esc_url( get_permalink($found_post_id) )."' target='_Blank'>View</a> | <a href='post.php?post=".$found_post_id."&action=edit'>". $post_title . "</a><p>";

endif;

WordPress vérifie si la publication existe par titre

function wp_exist_post_by_title( $title ) {
    global $wpdb;
    $return = $wpdb->get_row( "SELECT ID FROM wp_posts WHERE post_title = '" . $title . "' && post_status = 'publish' && post_type = 'post' ", 'ARRAY_N' );
    if( empty( $return ) ) {
        return false;
    } else {
        return true;
    }
}

// usage
if( wp_exist_post_by_title( $post->name ) ) {
// post exist
} else { 
// post does not exist
}