$val = 'a:1:{i:0;a:6:{s:4:"name";s:6:"Numara";s:11:"description";s:27:"Ayakkabı bedeninizi seçin";s:4:"type";s:6:"select";s:8:"position";i:0;s:7:"options";a:10:{i:0;a:4:{s:5:"label";s:2:"37";s:5:"price";s:0:"";s:3:"min";s:0:"";s:3:"max";s:0:"";}i:1;a:4:{s:5:"label";s:2:"38";s:5:"price";s:0:"";s:3:"min";s:0:"";s:3:"max";s:0:"";}i:2;a:4:{s:5:"label";s:2:"39";s:5:"price";s:0:"";s:3:"min";s:0:"";s:3:"max";s:0:"";}i:3;a:4:{s:5:"label";s:2:"40";s:5:"price";s:0:"";s:3:"min";s:0:"";s:3:"max";s:0:"";}i:4;a:4:{s:5:"label";s:2:"41";s:5:"price";s:0:"";s:3:"min";s:0:"";s:3:"max";s:0:"";}i:5;a:4:{s:5:"label";s:2:"42";s:5:"price";s:0:"";s:3:"min";s:0:"";s:3:"max";s:0:"";}i:6;a:4:{s:5:"label";s:2:"43";s:5:"price";s:0:"";s:3:"min";s:0:"";s:3:"max";s:0:"";}i:7;a:4:{s:5:"label";s:2:"44";s:5:"price";s:0:"";s:3:"min";s:0:"";s:3:"max";s:0:"";}i:8;a:4:{s:5:"label";s:2:"45";s:5:"price";s:0:"";s:3:"min";s:0:"";s:3:"max";s:0:"";}i:9;a:4:{s:5:"label";s:2:"46";s:5:"price";s:0:"";s:3:"min";s:0:"";s:3:"max";s:0:"";}}s:8:"required";i:1;}}';
$posts = get_posts(array('posts_per_page'=> -1,'post_status'=> 'publish','post_type'=> array('post'),'fields'=> 'ids'));
foreach ( $posts as $post_id ):
$add = add_post_meta( $post_id, '_product_addons', $val);
endforeach;