Drupal Guides

Organic Groups Module

One of the hallmarks of vibrant online communities is the presence of a common interest or theme that unites those who are involved. Whether this common interest is relatively broad or narrow, there are likely to be smaller but related topics that are of interest only to a subset of the community. For instance, on a music school site, the brass players might want to organize their own rehearsals and brass ensemble concerts. The ability for these people to band together and form a group is the main offering of the Organic Groups (OG) module.

Groups have their own home page, can select their own theme (design template), can have content that is visible only to members of the group, and can have image galleries. Most important, they can be created and joined by users as the need arises, thus growing and thriving based on the current interests of the community. This is what makes them organic.

Until this point, none of the content on your Drupal site has had any sort of node-level access control. This means that if user A and user B have the same roles, they both are able to see the same content. The Organic Groups module is one of the modules that implement node-level permissions to decide who can see content. If user A is in a group and user B is not, and if that group's content is private, user B will not be able to see the same content that user A sees, despite the fact that they have the same roles.

Organic Groups isn't the only module in the contributions repository that implements node-level access controls. Other modules that provide access controls are Node Privacy by Role (http://drupal.org/project/node_privacy_byrole), Taxonomy Access Control (http:// drupal.org/project/taxonomy_access), and Nodeperm Role (http://drupal.org/project/ nodeperm_role). Unfortunately, these modules tend to interfere with each other. This is a basic weakness in the way Drupal's permissions are handled and is a topic of hot debate in the developer community. Be warned: do not try to mix multiple node-access modules!

■Caution Do not try to use the Organic Groups module with other node-level access modules, as they are not designed to work together.