Updating custom fields with external data

Please refer the tutorial explains how to read data from the CSV and create and update existing post. It also explain how to update acf fields.

http://www.pearlbells.co.uk/insert-udpate-wordpress-post-programmatically/

Paste the code for creating and updating posts.

function postExists($postCSVContent,$parentId , $mydb) {

$mydb->get_results($mydb->prepare('SELECT ID FROM `wp_posts` WHERE ID = %d',$postCSVContent[0]));

if( $mydb->num_rows >  0) {

    echo 'Post '.$postCSVContent[0].' exist'.PHP_EOL;
    $template_file = get_post_meta( $postCSVContent[0], '_wp_page_template', true );
    echo 'Template File : '.$template_file.PHP_EOL;

    $updatePost = array(   
        'ID' => $postCSVContent[0],
        'post_title'    => $postCSVContent['1'],
        'post_content'  => $postCSVContent['2'],
        'post_type' => 'doors',
        'post_status'   => 'publish',
        'post_author'   => 1
    );

    wp_update_post( $updatePost );

    update_post_meta( $postCSVContent[0], '_wp_page_template', $template_file );
    updateAcf( $postCSVContent , $postCSVContent[0] );

}
else
{
    echo 'Post '.$postCSVContent[0].' is not existing'.PHP_EOL;        
    echo 'Post parent '.$parentId.PHP_EOL;

    $newIds = wp_insert_post( array(
            'post_title' => $postCSVContent['1'],
            'post_content' => $postCSVContent['2'],
            'post_type' => 'doors',
            'post_status' => 'publish',        
            'post_author'   => 1,
            'post_parent' => $parentId
    ));

    updateAcf( $postCSVContent , $newIds );
    return $newIds;

}

You can use PHP's fgetcsv() or str_getcsv() function to parse the uploaded CSV file. Your CSV will need to include a column with the Post's ID as well as the columns matching up to your custom field names. Loop through the CSV and for each line update the custom fields for that post using update_post_meta()

http://php.net/manual/en/function.fgetcsv.php

http://php.net/manual/en/function.str-getcsv.php

http://codex.wordpress.org/Function_Reference/update_post_meta