I have a page where I want to embed a front end form. This will be unique to a user and users should only edit their own page/forms.

Ideally I want to set the CPT post ID.

When I use the code below with the URL http://../forms/sample/?_post[ID]=364 all works as expected, it updates the existing CPT.

<?php
/*
Title: Post Submit
Method: post
Message: Saved
Logged in: true
*/

// Where to save this form
piklist('field', array(
  'type' => 'hidden'
  ,'scope' => 'post'
  ,'field' => 'post_type'
  ,'value' => 'cpt1'
));

piklist('field', array(
      'type' => 'select'
      ,'field' => 'cpt1_field1'
      ,'label' => 'Field1'
      ,'scope' => 'post_meta'
      ,'attributes' => array(
        'class' => 'text'
      )
     ,'choices' => array(
          '1' => 'Option1',
          '2' => 'Option2',
          '3' => 'Option3',
          '4' => 'Option4'
     )

));

  // Submit button
  piklist('field', array(
    'type' => 'submit'
    ,'field' => 'submit'
    ,'value' => 'Submit'
  ));

?>

What I really want is for the form to load when a user visits http://../forms/sample/

I’ve tried:

$post = get_post(374);
setup_postdata( $post );

but I assume that other code for the form runs before this. Is there a way to set the post id in the code rather than the URL?