Allow OpenID users to leave comments on Plone-based website

Every good blog should have ability to leave a comment on blog entry. Plone since version 3.0 has built in discussion support. To enable it, editor must check Allow comments checkbox on edit form.

By default only logged in users can leave comments. This approach is good for administrators (less comment spam), but is quite annoying for viewers - because they must create account. But there is solution good for both sides - OpenID.

To add OpenID support to Plone-based website just go to: Site Setup / Add-on Products and install OpenID Authentication Support. Now users can log in with OpenID, but still such users can't see "Add Comment" button. To fix it I had to look into Plone code, because Google couldn't find any useful linka. Fix is very easy - authenticated user must have Reply to item permission.

Solution step by step:

• install OpenID Authentication Support in Site Setup / Add-on Products,
• go to Security form (in ZMI) - just add manage_access to URL (e.g.: http://example.com/plone-site/manage_access),
• set Reply to item permission for Authenticated users (click checkbox in row Reply to item for column Authenticated and click Save Changes button).