Enables you to limit edit access (by role) to any field in the page editor.
Place all of the files for this module in /site/modules/PageEditFieldPermission/
This module hooks in to modify the behavior of Page::editable, which is used throughout ProcessWire, but most notably by Page Edit. This module looks for permissions in the system that follow the name format of page-edit-[field] where [field] is the name of an existing field in the system. When it finds such a permission during a Page::editable call, it checks to see if the roles from the current user have this permission assigned. If they do not, then permission to the relevant field is refused, thereby preventing edit access to the field.
Once the module is installed, you get a set of checkboxes on the module configuration screen. Check the boxes next to each field that you would like it to create permissions for. (Alternatively, you can create the permissions yourself, so this is just a shortcut). You should only create permissions for fields that you intend to limit access to.
Once your new page-edit-[field] permissions are created, any non-superuser roles that previously had access to edit those fields will no longer have access to edit them. To give them access, you must edit a role and check the box for the relevant permission.
November 2, 2012 by Ryan Cramer