Simulating dependent LOV using EJB Native Query

This Use case simulates dependent LOV. Consider a case where we need to retrieve employees where Department and Employees entities are associated by One to Many mapping. Here employees table has more number of records, if the entire records are  displayed in single ADF table. It will be difficult for user to search, Filter or traverse to the exact record.

Model Diagram: Employees, Departments table schema.
ModelDiagram.png

Below Employees details page has more number of records, User will not be able to see all the records at the same time on web page. User has to scroll down to find the exact record.

MoreRecords.PNG


Toolbar filters is one of the solution for navigating to the records, Toolbar filter enables the user to filter the rows in a table. Using toolbar filters performance issues can be improved by reducing result set size while loading the page.

We will try to achieve the toolbar filters by simulating dependent LOV using EJb Native Query. From the above Employees Details Page, select the departmentId and jobId as toolbar filters.

First, create entities based on Department, Employees, then create a stateless session bean and data control for the session bean. Add the below code to the session bean and expose the method in local/remote interface and generate a data control for that.

Note:- Here in the below code "em" is a EntityManager.

public List<Employees> EmployeesFilteredResult(Long departmentId,
                                                   String jobId) {
        String queryString = null;
        if (departmentId == null &amp;&amp; jobId == null) {
            queryString =
                    "select * from Employees where department_id like '%' and job_id like '%'";
        } else if (departmentId != null &amp;&amp; jobId == null) {
            queryString =
                    "select * from Employees where department_id = " + departmentId +
                    " and job_id like '%'";
        } else if (departmentId != null &amp;&amp; jobId != null) {
            queryString =
                    "select * from Employees where department_id = " + departmentId +
                    " and job_id = '" + jobId + "'";
        }
        System.out.println(queryString);
        Query genericSearchQuery =
            em.createNativeQuery(queryString, Employees.class);
        return genericSearchQuery.getResultList();
}

public List<String> EmployeesDistinctJobByDept(Long departmentId) {
        List<String> empResultList = new ArrayList<String>();
        try {
            String queryString =
                "select distinct JOB_ID from Employees where department_id = " +
                departmentId;
            System.out.println(queryString);
            Query genericSearchQuery =
                em.createNativeQuery(queryString, "DistinctSearch");
            List resultList = genericSearchQuery.getResultList();
            Iterator resultListIterator = resultList.iterator();
            while (resultListIterator.hasNext()) {
                Object col[] = (Object[])resultListIterator.next();
                empResultList.add((String)col[0]);
            }
            return empResultList;
        } catch (NullPointerException npe) {
            return empResultList;
        }
}

In the ViewController create a file DependentLOV.jspx page, from Data Control palette  and drop Panel Collection component, drop ADF toolbar inside the Panel Collection area, drop Panel Group Layout inside ADF toolbar. From DataControl palette drag and drop departmentsFindAll->Single Selection as ADF Select One Choice, In Edit List Binding select departmentName as Display Attribute.

DeptEditList.PNG

Select the departmentName select one choice, In Property Inspector make AutoSubmit: true, edit ValueChangeListener and create a DependentLOV.java managed bean with scope as "sessionScope"and create new method "selectedDeptIdValue", Open DependentLOV.java and paste the below code.

    private String deptIdValue;
    private String JobIdValue;
    public void setDeptIdValue(String deptIdValue) {
        this.deptIdValue = deptIdValue;
    }

    public String getDeptIdValue() {
        return deptIdValue;
    }

    public void setJobIdValue(String JobIdValue) {
        this.JobIdValue = JobIdValue;
    }

    public String getJobIdValue() {
        return JobIdValue;
    }

Right click on DependentLOV.jspx go to page definition. Create control binding by selecting attributeValues in Insert Item dialog window.

DeptIdListBinding.PNG


From DataControl palette drag and drop EmployeesDistinctJobByDept->return->element as Single Selection->ADF Select One Choice inside ADF toolbar, In Edit Action Binding select the parameter value as #{DependentLOV.deptIdValue}

EmployeesDistinctJobByDeptId.PNG


Select the jobId select one choice, In Property Inspector make AutoSubmit: true and set partialTriggers to departmentName select one choice . Edit ValueChangeListener and create a new method "selectedJobIdValue".

From DataControl palette drag and drop EmployeesFilteredResult->Employees as Table->ADF Read-only Table and select the columns to be displayed. In Edit Action Binding select the parameter as below

EmployeesFilteredValue.PNG


Select the employee table, In Property Inspector set partialTriggers to both departmentName and jobId select one choice. Open DependentLOV.java and overwrite the below code.

public void selectedDeptIdValue(ValueChangeEvent valueChangeEvent) {
        Integer stateIndex = (Integer)valueChangeEvent.getNewValue();
        BindingContainer bindings =
            BindingContext.getCurrent().getCurrentBindingsEntry();
        JUCtrlListBinding listBinding =
            (JUCtrlListBinding)bindings.get("departmentsFindAll");
        Object assignedId = null;
        if (listBinding != null) {
            assignedId =
                    listBinding.getDCIteratorBinding().getRowAtRangeIndex(stateIndex.intValue()).getAttribute("departmentId");
            Long deptId = Long.parseLong(assignedId.toString());
            this.setDeptIdValue(deptId);
        }
        OperationBinding operationBinding =
            bindings.getOperationBinding("EmployeesDistinctJobByDept");
        Object result = operationBinding.execute();
        this.setJobIdValue(null);
    }

    public void selectedJobIdValue(ValueChangeEvent valueChangeEvent) {
        Integer stateIndex = (Integer)valueChangeEvent.getNewValue();
        DCBindingContainer bindings =
            (DCBindingContainer)BindingContext.getCurrent().getCurrentBindingsEntry();
        DCIteratorBinding tableIter =
            bindings.findIteratorBinding("EmployeesDistinctJobByDeptIter");
        RowSetIterator tableRowSetIter = tableIter.getRowSetIterator();
        Object iterRow = null;
        iterRow =
                tableRowSetIter.getRowAtRangeIndex(stateIndex.intValue()).getAttribute("element");
        this.setJobIdValue(iterRow.toString());
} 
Run the DependentLOV.jspx and select the Dept Name from Dept selection box. JobId selection box will be updated with JobId's associated with Dept Name and Employees table will be refreshed with records for the selected Dept Name. On select of both dept name and job id table will be refreshed with the respective records.

TableFilterResult.PNG


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