ADF With No Bindings: SortableFilterableCollectionModel Implementation

Not using ADF bindings but wanted to have a sortable table? This post is for you.
I am glad to share a sortable CollectionModel implementation that is so elegantly simple. :)

This model supports in-memory sorting and filtering. The filtering concept based on groovy will be discussed on a subsequent post.

package soadev.ext.trinidad.model;

import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;

import javax.el.ELContext;

import javax.faces.context.FacesContext;

import org.apache.myfaces.trinidad.model.CollectionModel;
import org.apache.myfaces.trinidad.model.SortCriterion;


public class SortableFilterableModel extends CollectionModel {
    private List wrappedData;
    private List<Integer> sortedFilteredIndexList;
    private Integer baseIndex;
    private SortCriterion sortCriterion = null;

    public SortableFilterableModel(List wrappedData) {
        super();
        this.wrappedData = wrappedData;
        sortedFilteredIndexList = new ArrayList<Integer>();
        for (int i = 0; i < wrappedData.size(); i++) {
            sortedFilteredIndexList.add(i);
        }
    }

    public Object getRowKey() {
        return isRowAvailable() ? baseIndex : null;
    }

    public void setRowKey(Object object) {
        baseIndex = object == null ? -1 : ((Integer)object);
    }

    public boolean isRowAvailable() {
        return sortedFilteredIndexList.indexOf(baseIndex) != -1;
    }

    public int getRowCount() {
        return sortedFilteredIndexList.size();
    }

    public Object getRowData() {
        return wrappedData.get(baseIndex);
    }

    public int getRowIndex() {
        return sortedFilteredIndexList.indexOf(baseIndex);
    }

    public void setRowIndex(int i) {
        if(i < 0 || i >= sortedFilteredIndexList.size()){
            baseIndex = -1;
        }else{
            baseIndex =  sortedFilteredIndexList.get(i);
        }
        
    }

    public Object getWrappedData() {
        return wrappedData;
    }

    public void setWrappedData(Object object) {
        this.wrappedData = (List)object;
    }

    public List<Integer> getSortedFilteredIndexList() {
        return sortedFilteredIndexList;
    }

    @Override
    public boolean isSortable(String property) {
        try {
            Object data = wrappedData.get(0);
            Object propertyValue = evaluateProperty(data, property);

            // when the value is null, we don't know if we can sort it.
            // by default let's support sorting of null values, and let the user
            // turn off sorting if necessary:
            return (propertyValue instanceof Comparable) ||
                (propertyValue == null);
        } catch (RuntimeException e) {
            e.printStackTrace();
            return false;
        }
    }

    private Object evaluateProperty(Object base, String property) {

        ELContext elCtx = FacesContext.getCurrentInstance().getELContext();
        //simple property -> resolve value directly
        if (!property.contains(".")) {
            return elCtx.getELResolver().getValue(elCtx, base, property);
        }
        int index = property.indexOf('.');
        Object newBase =
            elCtx.getELResolver().getValue(elCtx, base, property.substring(0,
                                                                           index));

        return evaluateProperty(newBase, property.substring(index + 1));
    }

    @Override
    public List<SortCriterion> getSortCriteria() {
        if (sortCriterion == null) {
            return Collections.emptyList();
        } else {
            return Collections.singletonList(sortCriterion);
        }
    }

    @Override
    public void setSortCriteria(List<SortCriterion> criteria) {
        if ((criteria == null) || (criteria.isEmpty())) {
            sortCriterion = null;
            // restore unsorted order:
            Collections.sort(sortedFilteredIndexList); //returns original order but still same filter
        } else {
            SortCriterion sc = criteria.get(0);
            sortCriterion = sc;
            _sort(sortCriterion.getProperty(), sortCriterion.isAscending());
        }
    }

    private void _sort(String property, boolean isAscending) {

        if (getRowCount() == 0) {
            return;
        }
        if (sortedFilteredIndexList!= null && !sortedFilteredIndexList.isEmpty()) {
            Comparator<Integer> comp = new Comp(property);
            if (!isAscending)
                comp = new Inverter<Integer>(comp);
            Collections.sort(sortedFilteredIndexList, comp);
        }
    }

    private final class Comp implements Comparator<Integer> {
        public Comp(String property) {
            _prop = property;
        }

        public int compare(Integer x, Integer y) {
            Object instance1 = wrappedData.get(x);
            Object value1 = evaluateProperty(instance1, _prop);

            Object instance2 = wrappedData.get(y);
            Object value2 = evaluateProperty(instance2, _prop);

            if (value1 == null)
                return (value2 == null) ? 0 : -1;

            if (value2 == null)
                return 1;

            if (value1 instanceof Comparable) {
                return ((Comparable<Object>)value1).compareTo(value2);
            } else {
                // if the object is not a Comparable, then
                // the best we can do is string comparison:
                return value1.toString().compareTo(value2.toString());
            }
        }
        private final String _prop;
    }

    private static final class Inverter<T> implements Comparator<T> {
        public Inverter(Comparator<T> comp) {
            _comp = comp;
        }

        public int compare(T o1, T o2) {
            return _comp.compare(o2, o1);
        }

        private final Comparator<T> _comp;
    }
}

sample page

<?xml version='1.0' encoding='UTF-8'?>
<jsp:root xmlns:jsp="http://java.sun.com/JSP/Page" version="2.1"
          xmlns:f="http://java.sun.com/jsf/core"
          xmlns:h="http://java.sun.com/jsf/html"
          xmlns:af="http://xmlns.oracle.com/adf/faces/rich">
  <jsp:directive.page contentType="text/html;charset=UTF-8"/>
  <f:view>
    <af:document id="d1">
      <af:form id="f1">
        <af:panelCollection id="pc1">
          <f:facet name="menus"/>
          <f:facet name="toolbar">
            <af:toolbar id="t2">
              <af:commandToolbarButton text="Action" id="ctb1"
                                       actionListener="#{viewScope.sortableFilterableForm.action}"/>
            </af:toolbar>
          </f:facet>
          <f:facet name="statusbar"/>
          <af:table var="row" rowBandingInterval="0" id="t1"
                    value="#{viewScope.sortableFilterableForm.model}"
                    rowSelection="multiple"
                    binding="#{viewScope.sortableFilterableForm.table}"
                    selectedRowKeys="#{viewScope.sortableFilterableForm.selection}"
                    queryListener="#{viewScope.sortableFilterableForm.tableFilter}"
                    filterModel="#{viewScope.sortableFilterableForm.descriptor}"
                    filterVisible="true" emptyText="no result found">
            <af:column sortable="true" headerText="Job Id" align="start"
                       id="c2" filterable="true" sortProperty="jobId">
              <af:outputText value="#{row.jobId}" id="ot1"/>
            </af:column>
            <af:column sortable="true" headerText="Job Title" align="start"
                       id="c4" filterable="true" sortProperty="jobTitle">
              <af:outputText value="#{row.jobTitle}" id="ot4"/>
            </af:column>
            <af:column sortable="true" headerText="Max Salary" align="start"
                       id="c1" filterable="true" sortProperty="maxSalary">
              <af:outputText value="#{row.maxSalary}" id="ot3"/>
            </af:column>
            <af:column sortable="true" headerText="Min Salary" align="start"
                       id="c3" filterable="true" sortProperty="minSalary">
              <af:outputText value="#{row.minSalary}" id="ot2"/>
            </af:column>
            <af:column sortable="true" headerText="Job Type" align="start"
                       id="c5" filterable="true" sortProperty="jobType.color">
              <af:outputText value="#{row.jobType.color}" id="ot5"/>
            </af:column>
          </af:table>
        </af:panelCollection>
      </af:form>
    </af:document>
  </f:view>
</jsp:root>

This is somewhat derived from the trinidad SortableModel implementation but even made simpler.

ADF With no Bindings: Understanding the Trinidad CollectionModel

Did you ever wonder what the trinidad CollectionModel is good for? Well, I did.
According to the docs...

10.2 Displaying Data in Tables 

The table component uses a CollectionModel class to access the data in the underlying collection. This class extends the JSF DataModel class and adds on support for row keys and sorting. In the DataModel class, rows are identified entirely by index. This can cause problems when the underlying data changes from one request to the next, for example a user request to delete one row may delete a different row when another user adds a row. To work around this, the CollectionModel class is based on row keys instead of indexes. 

If we look at MyFaces Trinidad javadoc, it states almost the same.
There are only two points described above: Support for row keys aside from index; and to enable sorting.

But digging deeper by observing the behavior of tables based on ADFm and creating a trivial implementation, I noted the following purposes:

• On demand data access
  
• Support for row keys aside from index
  
• To enable sorting
  
• Filtering
  
• Data caching
  

How to implement CollectionModel?

To implement a CollectionModel you need to provide implementation of at least the following abstract methods:

public Object getRowKey(); 
    public void setRowKey(Object object);
    public boolean isRowAvailable();
    public int getRowCount();
    public Object getRowData();
    public int getRowIndex();
    public void setRowIndex(int i);
    public Object getWrappedData();
    public void setWrappedData(Object object);

How does CollectionModel suppose to behave?

The collection model is a black box in which you will provide input and get output. There are two ways to provide an input:

• setRowIndex(int i)
  
• setRowKey(Object object)
  

The table component is doing the following on collection model upon initial load:

1. Reset the model by calling setRowIndex(int i) with a parameter of -1 and calling setRowKey(Object object) with a null parameter; It does this at least twice.
   
2. invokes int getRowCount() to have an estimate of the total number of records.
   
3. call setRowIndex(int i) with index starting from 0.
   
4. check if there is data on the current index by calling isRowAvailable(). If it returns true then it will proceed to step 5 below else stop from here.
   
5. call getRowData(). to retrieve the data on the current index as set on step 3. Next.. back to step 3 until the browser window is full.
   
6. If the user scrolls down then back to step 3.
   

What does this mean? It means that if you implement a CollectionModel you need to ensure that when the user calls one of the input methods above, you should be able to give a proper output upon their subsequent call to: isRowAvailable(), getRowData, getRowKey(), and getRowIndex().

Sample Trivial Implementation

package soadev.view.model;

import java.util.List;

import org.apache.myfaces.trinidad.model.CollectionModel;

import soadev.domain.Job;


public class MyCollectionModel extends CollectionModel {
    private List wrappedData;
    private int index;

    public MyCollectionModel() {

    }

    private int indexOf(Object rowKey) {
        int result = -1;
        for (Object obj : wrappedData) {
            result++;
            Job job = (Job)obj;
            if (rowKey.equals(job.getJobId())) {
                return result;
            }
        }
        return result;
    }

    public MyCollectionModel(List wrappedData) {
        this.wrappedData = wrappedData;
    }

    public Object getRowKey() {

        if (index < 0 || index >= wrappedData.size()) {
            return null;
        }
        Job job = (Job)wrappedData.get(index);
        System.out.println("getRowKey() return: " + job.getJobId());
        return job.getJobId();
    }

    public void setRowKey(Object object) {
        System.out.println("setRowKey(Object object) " + object);
        if (object == null) {
            index = -1;
        } else {
            index = indexOf(object);
        }
    }

    public boolean isRowAvailable() {
        System.out.println("isRowAvailable()  return: " +
                           (index > -1 && index < wrappedData.size()));
        return index > -1 && index < wrappedData.size();
    }

    public int getRowCount() {
        System.out.println("getRowCount() return: " + wrappedData.size());
        return wrappedData.size();
    }

    public Object getRowData() {
        System.out.println("getRowData()");
        if (isRowAvailable()) {
            System.out.println("return: " + wrappedData.get(index));
            return wrappedData.get(index);
        }
        return null;
    }

    public int getRowIndex() {
        System.out.println("getRowIndex() return: " + index);
        return index;
    }

    public void setRowIndex(int i) {
        System.out.println("setRowIndex(int i) " + i);
        index = i;
    }

    public Object getWrappedData() {
        System.out.println("getWrappedData() return: " + wrappedData);
        return wrappedData;
    }

    public void setWrappedData(Object object) {
        System.out.println("setWrappedData(Object object)" + object);
        this.wrappedData = (List)object;
    }

}

Sample console output showing invocation sequence

Target URL -- http://127.0.0.1:7101/Application1-Web-context-root/faces/basic_collection_model.jspx
setRowIndex(int i) -1
setRowKey(Object object) null
isRowAvailable()  return: false
setRowKey(Object object) null
isRowAvailable()  return: false
setRowKey(Object object) null
isRowAvailable()  return: false
setRowKey(Object object) null
isRowAvailable()  return: false
setRowIndex(int i) -1
getRowCount() return: 500
setRowKey(Object object) null
isRowAvailable()  return: false
setRowIndex(int i) 0
isRowAvailable()  return: true
getRowData()
isRowAvailable()  return: true
return: soadev.domain.Job@3a971ffdjob Title 0
getRowKey() return: job0
isRowAvailable()  return: true
getRowKey() return: job0
getRowIndex() return: 0
getRowIndex() return: 0
getRowIndex() return: 0
getRowIndex() return: 0
getRowIndex() return: 0
setRowIndex(int i) 1
isRowAvailable()  return: true
getRowData()
isRowAvailable()  return: true
return: soadev.domain.Job@1db884a1job Title 1
getRowKey() return: job1
isRowAvailable()  return: true
getRowKey() return: job1
getRowIndex() return: 1
getRowIndex() return: 1
getRowIndex() return: 1
getRowIndex() return: 1
getRowIndex() return: 1
setRowIndex(int i) 2
...
... and so on

GitHub

ADF With No Bindings: Simple Tables

In this post, I will describe how to work with simple tables without a binding layer in Oracle ADF Faces 11g RC.


Summary:

• Create a backing bean
• Drop a <af:table/> component to the page
• How to add new row
• Managed row selection
• Handling selection events

Create a backing bean

//package and import statements
public class SimpleTableForm {
    private List<Job> jobList;
    private RichTable jobTable;
    private RichPanelGroupLayout panelGroup1;

    public void setJobList(List<Job> jobList) {
        this.jobList = jobList;
    }

    public List<Job> getJobList() {
        if (jobList == null) {
            jobList = new ArrayList<Job>();
        }
        return jobList;
    }
//other codes

Drop a <af:table/> component to the page

When you drag and drop a table from the component palette, the "Create ADF Table" wizard will show. I highly recommend that you specify the Element Type so that JDeveloper will auto populate the corresponding columns for you.

How to add new row

To add a new row you just have to add a new item into the corresponding List that holds your data as in the following example:

//adds new row
    public void addJob(ActionEvent actionEvent) {
        Job job = new Job();
        getJobList().add(job);
    }

You need to set partial triggers to see the newly added row in the table.

<af:panelCollection id="pc1">
              <f:facet name="toolbar">
                <af:toolbar id="t2">
                  <af:commandToolbarButton text="Add" id="ctb1"
                                           actionListener="#{viewScope.simpleTableForm.addJob}"/>
                </af:toolbar>
              </f:facet>
              <af:table value="#{viewScope.simpleTableForm.jobList}" var="row"
                        rowBandingInterval="0" id="t1"
                        binding="#{viewScope.simpleTableForm.jobTable}"
                        rowSelection="single"
                        selectionListener="#{viewScope.simpleTableForm.tableRowSelected}"
                        partialTriggers="::ctb1">

Managed row selection

To get hold of the selected row, you have two options:

1. Create an attribute selectedJob and update this value in a selectionListener. This seems better to avoid problems related to serialization of JSF components on scopes higher than request, but I prefer the next option.
   
2. Bind the table component to the backing bean. Sometimes you need to manage the current selection on the table component, perhaps to make the newly added row as the current row. The serialization issue can be resolve through the use of "org.apache.myfaces.trinidad.util.ComponentReference" class.
   Code below shows a table component bind in the backing bean using a ComponentReference:
   

   private ComponentReference<RichTable> jobTable;
       
       public void setJobTable(RichTable jobTable) {
           if(this.jobTable == null){
               this.jobTable = ComponentReference.newUIComponentReference(jobTable);
           }
       }
   
       public RichTable getJobTable() {
           return jobTable == null? null: jobTable.getComponent();
       }
   

   Below is an updated code to make the newly added row as currently selected.
   

   public void addJob(ActionEvent actionEvent) {
           Job job = new Job();
           getJobList().add(job);
           RichTable table = getJobTable();
           RowKeySet selection = table.getSelectedRowKeys();
           selection.clear();
           selection.add(getJobList().size() - 1);
       }
   

   View selected row...
   

   public Job getSelectedJob() {
           RichTable table = getJobTable();
           if (table.getEstimatedRowCount() > 0) {
               return (Job)getJobTable().getSelectedRowData();
           }
           return null;
       }
       
       public void viewSelected(ActionEvent actionEvent) {
           Job selected = getSelectedJob();
           String msg = null;
           if (selected != null) {
               msg = "Selected :" + selected.getJobId() + " " + selected.getJobTitle();
           } else {
               msg = "No selection.";
           }
           FacesMessage fm =
               new FacesMessage(FacesMessage.SEVERITY_INFO, msg, "");
           FacesContext.getCurrentInstance().addMessage(null, fm);
       }
   

Handling selection events

Simple tables based on ordinary list object does not throw selection events which you can use as partial triggers. In order to update some part of the page in response to a user selection, you need to add a selection listener and addPartialTarget the corresponding component from there as in the following example:

public void tableRowSelected(SelectionEvent selectionEvent) {
        AdfFacesContext.getCurrentInstance().addPartialTarget(getPanelGroup1());
    }

Further thoughts

I hope you learned something from this simple post. In the next post, I will explain the "CollectionModel".