ADF Basics: Iterate over master detail viewObject using view link accessor

Hello All

This post is about iterating over master and it's child view object using view link accessor, this is very basic thing of framework still some find (those who are starting with ADF) it difficult so I thought to write it here

Here I am using Departments and Employees table of HR Schema to create Master-Detail relation and due to view link relation, Department viewObject has view link accessor of Employees viewObject

ADF Basics: Delete child records on delete of parent record, Overriding remove() in EntityObject class

This post is about one basic question of Master-Detail relation between business components
How to delete all child records on delete of parent record ?
So answer is quite simple , see the steps how to achieve this?

• Create a Fusion Web Application and prepare model project using Departments and Employees table of HRSchema.
  you can see multiple associations and viewLinks are created automatically due to foreign key relation in database





• Here Departments is parent table and Employees is child, so there is an association between both entity objects , open this association and goto Association Properties . Now you can see source and destination accessor name that are created in both entity objects







• Next step is to create EntityObject java class. To do this open Departments entity object -- go to java section-- click on edit icon and check the box to create class and required methods
  See Accessors and Remove Method will be created in this class





• Open DepartmentsEOImpl class and check there is a method that returns RowIterator of Employees (this is Accessor)



    /**
     * @return the associated entity oracle.jbo.RowIterator.
     */
    public RowIterator getEmployeesEO1() {
        return (RowIterator)getAttributeInternal(EMPLOYEESEO1);
    }



• Now locate remove method in EOImpl, this method is called every time when delete operation for Departments is executed so add this code to remove(); method



    /**
     * Add entity remove logic in this method.
     */
    public void remove() {
        //Get all Employees of currenlty selected Department
        RowIterator employees = getEmployeesEO1();
        while (employees.hasNext()) {
            //Delete all Employees
            employees.next().remove();
        }
        //Delete Department itself after deleting all Employees associated with it
        super.remove();
    }

This is how we can make use EntityObject class and Association accessors, in the same way other operation can be performed as updating all child rows, sum of a column of child records etc
Thnaks , Happy Learning :)

Use View Link Accessor to call aggregate functions, set attribute value , set bind variables value (Oracle ADF)

Hello All

This post is about various usage of view link accessor  , when we create viewLink between two viewObjects , destination accessor is created by default in master viewObject, there is check box to create source accessor also at same time

We can use this view link accessor for calculating attribute's sum, setting value of attributes etc

here Departments is master viewObject and Employees is it's detail, after creating viewLink you can see in viewObject xml source there accessor is present

In Departments ViewObject- 

<ViewLinkAccessor
    Name="Employees"
    ViewLink="sample.model.view.link.DeptTOEmpVL"
    Type="oracle.jbo.RowIterator"
    IsUpdateable="false"/>

In EmployeesViewObject- 
 

<ViewLinkAccessor
    Name="Departments"
    ViewLink="sample.model.view.link.DeptTOEmpVL"
    Type="oracle.jbo.Row"
    Reversed="true"
    IsUpdateable="false"/>

So what is the use of these view link accessors ?
Master accessor in detail viewObject returns current Row of master viewObject, when you generate RowImpl class for detail viewObject , it also has a method for this accessor

    /**
     * Gets the associated <code>Row</code> using master-detail link Departments.
     */
    public Row getDepartments() {
        return (Row) getAttributeInternal(DEPARTMENTS);
    }

    /**
     * Sets the master-detail link Departments between this object and <code>value</code>.
     */
    public void setDepartments(Row value) {
        setAttributeInternal(DEPARTMENTS, value);
    }

Detail accessor in master viewObject returns a row set of all row of details viewObject that are currently referenced by master record

    /**
     * Gets the associated <code>RowIterator</code> using master-detail link Employees.
     */
    public RowIterator getEmployees() {
        return (RowIterator) getAttributeInternal(EMPLOYEES);
    }

Now see what we can do with viewLink Accessor

1. Get master attribute value in detail viewObject

suppose i have to get a attribute's value from Master viewObject (Departments) in a attribute of detail viewObject (Employee)

in this example i am getting managerId from Departments ViewObject so for this just write in expression of Employee's ManagerId field

viewLinkAccesorName.AttributeName

now run BC4J tester and check - create new record in Employee and see managerId from Departments is auto populated

 on creating new record-

2. Call aggregate function to calculate sum of an attribute of detail viewObject

suppose now i have to calculate total salary of a Department (sum of Employees salary of that department)

for this purpose just call sum function to calculate sum of all rows of detail RowSet 

take a transient attribute in Departments ViewObject and write in it's expression

viewLinkAccesorName.sum("AttributeName")

 Run ApplicationModule and see-

3. Set bind variable value as per master viewObject's attribute (pass value from master viewObject)

This  is tricky part as we can not set bind variable value through expression as it doesn't recognize view link accessor name.

created a viewCriteria and bind variable for managerId in Employee viewObject

applied this criteria to Employees viewObject instance in Application Module (Just Shuttle criteria to selected side)

now to set bind variable's value we have to override prepareRowSetForQuery method in Employees VOImpl class

this method gets the value of managerId from currentRow of master ViewObject (Departments)and sets in bind variable of Employees viewObject

    @Override
    public void prepareRowSetForQuery(ViewRowSetImpl viewRowSetImpl) {
        RowSetIterator[] masterRows = viewRowSetImpl.getMasterRowSetIterators();
        if (masterRows != null && masterRows.length > 0 && masterRows[0].getCurrentRow() != null &&
            masterRows[0].getCurrentRow().getAttribute("ManagerId") != null) {
            Integer managerId = (Integer) masterRows[0].getCurrentRow().getAttribute("ManagerId");
            viewRowSetImpl.ensureVariableManager().setVariableValue("BindManagerId", managerId);
            System.out.println("ManagerID in bind Var-" + managerId);

        }
        super.prepareRowSetForQuery(viewRowSetImpl);
    }

now run AM and check it-

Happy Learning :)