<form action="https://www.sandbox.paypal.com/cgi-bin/webscr" method="post" target="_top">
  <input type="hidden" name="cmd" value="_s-xclick">
  <input type="hidden" name="hosted_button_id" value="BSTSTWJ2TNN">
  <input type="hidden" name="custom" value="this.user?.uid">
  <button mat-flat-button color="warn">
    {{
      project.name
    }}
  </button>  
</form>

I need to pass an angular property named "this.user?uid" from a component to an HTML hidden form value with the name "custom" and will be passed to a paypal transaction.

I am not quite sure how to do this in angular but I have seen examples done in PHP.

Can anyone please point me to the right direction?

Thank you!