How to add checkout fields in magento 2 and save them in db
<p>I need to add some fields to the shipping address form from checkout page, and then save them in db.
I developed a module ( link to download: <a href="https://github.com/rlaa/custom-checkout-fields/blob/master/Test_attr.zip" rel="nofollow">https://github.com/rlaa/custom-checkout-fields/blob/master/Test_attr.zip</a>).</p>

<p>Steps to install it: </p>

<pre><code>php bin/magento setup:upgrade 

php bin/magento cache:clean

php bin/magento cache:flush
</code></pre>

<p>Delete all files in the pub/static/frontend and var/view_preprocessing directories.</p>

<p>When I click next button , custom checkout field is not sent in post request.</p>

<p>I don't know why this is happening.</p>