Drupal Form:want to show previous form value as default_value on page

Question

My Goal is if user is submitting this form with \"Product Name\" value as \"YYY\". On submit page should reload but this time \"Product Name\" should show previous valye as

Answer 1

In my case I had a couple of drop-downs. Submitting the form posted back to the same page, where I could filter a view and I wanted to show the previously selected options. On submitting the form I built a query string in the submit hook:

function myform_submit($form, &$form_state) {

  $CourseCat = $form_state['values']['coursecat']; 

  drupal_goto("courses" , array('query' => 
    array('cat'=>$CourseCat))
  );
}

In the form build hook, all I did was get the current query string and used those as default values, like so:

function myform_form($form, &$form_state) {
  $Params = drupal_get_query_parameters ();
  $CatTree = taxonomy_get_tree(taxonomy_vocabulary_machine_name_load ('category')->vid);

  $Options = array ();
  $Options ['all'] = 'Select Category';
  foreach ($CatTree as $term) {
        $Options [$term->tid] = $term->name;
  } 
  $form['cat'] = array(
    '#type' => 'select',
    '#default_value' => $Params['cat'],      
    '#options' => $Options
  );

  $form['submit'] = array(
    '#type' => 'submit',
    '#default_value' => 'all',
    '#value' => t('Filter'),
  );

  return $form;
}