magento2 admin : generate controller url for form action

Question

On a Magento2 admin page (order/view) I added a form using phtml file with block. I would like to define my form action to my controller url : www.xxx.com/admin_toto/foo/bar/index

How can I generate this url ?

<form id="test" method="post" action="<?php echo ADMIN_URL.'foo/bar/index'?>">
 <?php echo $block->getBlockHtml('formkey');?>
 <input>...</input>
 <span><button type="submit">Update</button></span>
</form>

Answer 1

try with

$block->getUrl('foo/bar/index');