hide a DIV on node edit form, but display on node creation

Question

I have a field that is part of a conditional related to several field collections. As such, it needs to be rendered when adding or editing a form. However, once the node has been created, I don't want users to be able to modify the value. So on the edit page, I want to hide the DIV surrounding it.

I thought I could trick it with CSS in Panels, but add and edit use the same page and the same CSS shows in each.

Answer 1

As both answers above mention, there are two ways to hide a field on the node edit form:

1. via css.
2. via a form alter hook.

CSS Solution

On the node creation page the body tag has class "page-node-add", but on the edit node page - "page-node-edit", so you can hide the field with CSS in your theme like so:

.page-node-edit .field-name-field-myfieldname {
  display: none;
}

The CSS-based solution has two main caveats:

1. An astute user will be able to unhide the field, modify it, and submit the form. There is nothing on the server-side checking to prevent submitting a change.
2. If you're using the admin theme on node edit, then adding custom css to the page is a bit more complicated than just adding this line of CSS to your front-end theme's stylesheet. You'll need to either add it via a custom module, or hack the admin theme (not recommended), or implement a custom child-theme of the admin theme.

For these reasons, I recommend the second option, use a form alter hook to hide the desired field:

Hook_Form_Alter Solution

You should add the following snippet in a custom module enabled on your site. You may either remove the form element entirely with '#access' => FALSE or leave the form element visible but non-editable using '#disabled' => TRUE.

/**
 * Implements hook_form_alter().
 */
function MYMODULE_form_alter(&$form, $form_state, $form_id) {
  if ($form_id == 'MYNODETTYPE_node_form') {
    if (isset($form['#node']) && isset($form['#node']->nid)){
      // Prevent editing a field once the node has been created by 
      // hiding the field entirely on the edit form.
      $form['field_MYFIELDNAME']['#access'] = FALSE;

      // Alternatively, if you want to display the field, but prevent
      // it from being edited, you can disable the form element.
      $form['field_MYFIELDNAME']['#disabled'] = TRUE;
    }
  }
}

This solution has no caveats really, and is probably the better solution.

Answer 2

Whene you go to node create page, the body tag has class "page-node-add", but on edit node page - "page-node-edit". So you can add CSS code:

.page-node-edit #your_div_id {display: none;}

Answer 3

You should inspect the node object to see if there is a nid, which is the primary identifier for the node table. If there is a nid, it is the edit page, and if there is no nid, then it is creation page.

Something like this:

function MYMODULE_form_alter(&$form, $form_state, $form_id) {
  if ($form_id == 'MYNODETTYPE_node_form) { // check for the node edit form
    if (isset($form['#node']) && $form['#node']->type == 'MYNODETTYPE'){ // check for your bundle here
      if (!isset($form['#node']->nid)) { // a node exists
        // create form

      }
      else { // no node exists yet
        // edit form
      }
    }
  }
}