A view link allows us to create a relationship between view objects. The relationship can be one-to-one, one-to-many, many-to-one, or many-to-many. The View Link Wizard and Editor lets us specify source and destination view objects, and links them using attributes selected.
To create a view link, we first need to have all the underlying view objects in place.
A view link is also like a Oracle Forms Block relation, that allows you to join two objects.

If you wish to create a master detail relation screen in ADF, then you must create View Links. As the user sets focus to the master row, the detail rows can be automatically queried using view link. This becomes possible when two view objects are related through a master-detail view link, and are in an application module, the iterator for the master view object automatically changes the detail rowset when the master row changes.

View links can optionally be created based on entity association [see this link for EO Assoc], but an association is not mandatory to create a view link.
A view link is similar to an association, but more flexible. It allows more relationships than equality between attributes and supports automatic master-detail synchronization.

Now, let us create a DepartmentVO.
Before we create a view link, we first need a parent view object. For this parent view object, we will make a child view object link to EmployeeVO

Click next, and select DepartmentEO on which this view object will be based upon, and then click Next again.

Select all the columns in the DepartmentEO so that each of the columns are available to the View Object Layer.

Click on next, no need to make changes here.

Click Finish and then move on to create the LocationVO

LocationVO is of course based on the LocationEO

Select all the columns in LocationEO so that each of these columns is available to the View Object Layer.

Next, we create a View Link, to create a linkage between the EmployeeVO view object and DepartmentVO view object. Right click on server sub-package

Give your view link a name.

The cardinality will dictate the relationship between the two view objects, i.e. one department can have more than one employees.
Select the DeptId from both the sides and click Add



Click on Next.

Click on Next.

Click on Finish.

Goto EmploeeAM.xml

Double click on Application Module to attach EmployeeVO, by leveraging the view Link that we have already created inprior steps.

Goto Data Model and select EmployeeVO via DepttoEmpVOLink-->Click on Right Arrow

The View Object link has now been created and added to the Application Module.

In the next article, you will see how to test the view link.

Anil Passi

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