Admin form action to another admin controller can not reach

Question

In Magento2, I create a form by phtml file in admin, but when I submit it, it always redirect to admin homepage, not reach another admin controller, how to fix it?

I guess the problem is in the action url, but I don't have a idea to fix it.

form codes

<form action="<?php echo $block->getUrl('migration/index/post') ?>" method="post" style="text-align: center;">
    <label for="sku">Sku: </label>
    <input type="text" name="sku" id="sku" size="40">
    <input type="submit" value="Submit">
</form>

Answer 1

Abdul's comment is right, I forget the form_key, but simply use $block->getFormKey() will not generate the form_key in phtml file. We need create the method in our block.

What is form_key

Form keys in Magento are a means of preventing against Cross Site Request Forgery, it instructs Magento to output and store a unique form key for a user session. All CSRF-protected Magento controller actions will verify against this before doing anything of value.

Create the getFormKey() in our block

<?php
namespace Vendor\Module\Block\Adminhtml\Index;

use Magento\Framework\Data\Form\FormKey;
use Magento\Framework\View\Element\Template;

class Form extends Template
{
    protected $_backendUrl;

    protected $formKey;

    /**
     * Form constructor.
     * @param Template\Context $context
     * @param array $data
     * @param FormKey $formKey
     */
    public function __construct(
        Template\Context $context,
        array $data = [],
        FormKey $formKey
    )
    {
        $this->formKey = $formKey;
        parent::__construct($context, $data);
    }

    /**
     * @return string
     */
    public function getFormKey()
    {
        return $this->formKey->getFormKey();
    }
}

Form Codes

<form action="<?php echo $block->getUrl('migration/index/post') ?>" method="post" style="text-align: center;">
    <input name="form_key" type="hidden" value="<?php echo $block->getFormKey() ?>">
    <label for="sku">Sku: </label>
    <input type="text" name="sku" id="sku" size="40">
    <input type="submit" value="Submit">
</form>