Is it possible to set an automatic value to a custom field while submitting the post in wordpress?
When I post I need that this custom field take automatically the first letter of the post title.
Example: If my title is "Example" The custom field value is "E".
Yes this is possible. If you're adding a custom field by a meta box you could do like this:
// add action to create your custom field
add_action( 'add_meta_boxes', 'create_meta_box' );
// add a callback that will be called when saving the post
add_filter( 'save_post', 'save_meta_box', 10, 2 );
// function that will create a meta box
function create_meta_box() {
add_meta_box('sample_meta_box', __('Sample Box'), 'display_meta_box');
}
// function that will display the actual meta box
function display_meta_box($post, $metabox) {
?>
<input name="sample" type="text" id="sample" value="<?php echo get_post_meta($post->ID, 'sample', true); ?>">
<?php
}
// function that will be called when the post is saved
function save_meta_box($post_id, $post) {
// default value for the field
$value = $_POST['post_title'][0];
// only use the default value if user haven't specified one
if(!empty($_POST['sample'])) {
$value = $_POST['sample'];
}
// update the meta data for the post
update_post_meta($post_id, 'sample', $value);
}
Of course you will have to change sample in this case to the name of your meta data field.
If you already have created a custom field through the administration interface, you could do like this:
// add a callback that will be called when saving the post
add_filter( 'save_post', 'save_custom_field', 10, 2 );
// called when updating a post
function save_custom_field($post_id, $post) {
// loop through the meta data
if(isset($_POST['meta'])) {
foreach($_POST['meta'] as $key => $value) {
// check if it's the correct field
if($value['key'] == 'sample') {
// this will always set the custom field to the first letter in the title
update_post_meta($post_id, 'sample', $_POST['post_title'][0]);
break;
}
}
}
}
Like in the first example you will have to change the sample to the name of your custom field.
