Trouble editing Drupal nodes? Check your input formats!

I ran into an annoying problem today where members of a certain administrative role could not edit nodes on a Drupal site.

I checked the following:

• The role had administer nodes, which should have given members the ability to edit any node.
• The role had the edit foo permission and the edit own foo permission.
• I tried getting rid of edit own foo in case it was conflicting with edit foo.
• I reset the node_access table.
• I emptied the cache.

Nonetheless, some nodes were editable, and some were not. Normally Drupal is very robust, and I just couldn't figure out why things were not working.

Finally, distraught, I went into the node module's code at http://api.drupal.org/api/file/modules/node/node.module/5 and clicked into the node_access function. Lo and behold, right at the top, it hit me like a brick:

  // If the node is in a restricted format, disallow editing.
  if ($op == 'update' && !filter_access($node->format)) {
    return FALSE;
  }

All of the nodes that I could not edit had been switched to use the Full HTML input format. I gave the role in question permission to use that input format, and I was good to go.

So there's the lesson for the day: if you can't edit a page, check the input format.

Hope this saves you from pounding your head against a desk like I did this afternoon.