anyway I want to share my code to make Mb Relationships can select only single value
in
"inc/class-mb-relationships-relationship.php"
search for function
"parse_meta_box_to"
put these code under line
$field['name'] = $this->to['meta_box']['field_title'];
like this
$field['name'] = $this->to['meta_box']['field_title'];
$field['clone'] = $this->to['clone'];// <<< option to selective clone on/off
$field['attributes']['required'] = $this->to['attributes']['required']; // set it required field
now we can use clone = false option
like this :
'to' => array(
'object_type' => 'post',
'post_type' => 'gallery',
'admin_column' => 'after title', // THIS!
'clone' => false, // <<<< add this line for turn off clone
'attributes' => array( // <<< for make field required
'required' => true, // <<< for make field required
), // <<< for make field required
'meta_box' => array(
'context' => 'normal',
),
),
.
