Discussions =========== This Discussions app is responsible for providing support for configuring discussion tools in the Open edX platform. This includes the in-built forum tool that uses the `cs_comments_service`, but also other LTI-based tools. Technical Overview ------------------ This app adds support for alternative Discussion providers, where a provider is initially an LTI app that can be embedded in the discussion tab. A list of supported providers is included configured in this app, with the features each app supports, its support level, and other details that are returned by the API and drive the UI for selecting and comparing providers in the course authoring MFE. Each context (course) has an associated `DiscussionConfiguration` object that specifies the provider to use for that course, and includes other configuration information for the course. For LTI-based providers, it's also linked to an `LtiConfiguration` entry. The `plugin_configuration` field on this model is to store provider/plugin-specific configuration that won't make sense for other plugins. Different parts of the course can be linked to different discussion topics. The standard use case here to have a topic for each Unit in the course. The `DiscussionTopicLink` model handles this association, and links a particular usage key in a particular course to a topic. The new Discussion API is driven entirely by these `DiscussionTopicLinks` in the database, so it's possible to have a third-party plugin that changes how and where these topic links are created. When a course is published, the `listen_for_course_publish` signal handler is called, and this signal in turn calls the update_discussions_settings_from_course_task` in the background. That task goes through the module store and builds a `CourseDiscussionConfigurationData` object that has all the relevant course discussion configuration information such as the course key, the provider type, whether in-context discussions are enabled, whether graded units are enabled, when unit level visibility is enabled. Other plugin configuration and a list of discussion contexts for which discussions are enabled. Each discussion context has a usage key, a title (the units name) an external id (the cs_comments_service id), it's ordering in the course, and additional context. It then sends its own signal that has the discussion configuration object attached. Finally, the handler for this discussion change signal, takes the information from the discussion change signal and compares it to the topics in the database, and does the following: - If it sees discussions contexts (units) without topics it creates new topics link entries for the new units. This will happen if you create a new unit, or enable discussions for a unit that previously had them disabled. - If it sees discussion topics without contexts it disables/archives them. This could happen when a unit is deleted or if a unit that previously had discussions enabled, now has discussions disabled. - If it sees any other change, i.e. unit name change etc. it applies that change to the database as well.