15.1 Introduction to Displaying Master-Detail Data

In ADF Business Components, a master-detail relationship refers to two view object instances that are related by a view link. As you may recall from Chapter 5, "Querying Data Using View Objects", a view link represents the relationship between two view objects, which is usually, but not necessarily, based on a foreign-key relationship between the underlying data tables. ADF uses the view link to associate a row of one view object instance (the master object) with one or more rows of another view object instance (the detail object).

View links support two different types of master-detail coordination: view link accessor attributes and data model view link instances (for more information, see Section 27.1.3, "Understanding View Link Accessors Versus Data Model View Link Instances"). However, when displaying master-detail data on a page using ADF data binding, you exclusively use data model view link instances, which support active data model master-detail coordination. To enable active data model master-detail coordination, you must add both the master view object and the detail view object instances to the application module data model (for more information, see Section 5.10.4.3, "How to Enable Active Master/Detail Coordination in the Data Model".) For example, in the SRDemo application, there is a view link from the ServiceRequests view object to the ServiceHistories view object based on the Svr_Id attribute (service request ID). Both the master and detail view objects have been added to the application module data model. So, a change in the current row of the master view object instance causes the rowset of the detail view object instance to refresh to include the details for the current master.

When objects have a master-detail relationship, you can declaratively create pages that display the data from both objects simultaneously. For example, the SRDemo application has a page that displays a service request in a form at the top of the page and its related service history in a table at the bottom of the page. This is possible because the service request and service history objects have a master-detail relationship. In this example, the service request is the master object and the service history is the detail object. The ADF iterators automatically manage the synchronization of the detail data objects displayed for a selected master data object.

Read this chapter to understand:

• Master-detail relationships in ADF

• How to identify master-detail objects on the Data Control Palette

• How to display master-detail objects in tables, forms, trees, tree tables, and inline tables

• How to display master-detail objects on different pages that are connected by a navigation component

• How ADF iterators manage the concurrency of master and detail objects

• The binding objects created when you use the Data Control Palette to create a master-detail UI component