This blog post demonstrates creating an ADF Faces RC af:tree component that sources its data from a hierarchical database table, and supports drag n drop of the nodes.

Both these topics have been discussed and demonstrated by other excellent bloggers, the core of this post is to bring both concepts together, with my usual own proof of concept documentation that may be useful to readers.

The ADF Faces RC support for hierarchical data sources was defined by Chandu Bhavsar.

The drag and drop support for af:trees was documented by Luc Bors.

(Definitely the kudos for this post must go to both Chandu and Luc for their posts that sparked the inspiration for mine)

Data model

In this example we'll use the following table:

CREATE TABLE organisations
(org_id NUMBER(4,0) NOT NULL
,parent_org_id NUMBER(4,0)
,name VARCHAR2(35) NOT NULL
,CONSTRAINT org_pk PRIMARY KEY (org_id)
,CONSTRAINT org_parent_fk
FOREIGN KEY (parent_org_id)
REFERENCES organisations (org_id));

Note the FK between the table and itself, essentially modelling that an organisation has sub-organisations (or agencies).

The data:

ORG_ID PARENT_ORG_ID NAME
------ ------------- -------------------------------
1000 (null) Sage Computing Services
1010 1000 Training Division
1030 1010 Self Study Program
1040 1010 Classroom Training
2264 (null) Australian Medical Systems
3210 (null) Conservation Society
3214 3210 Forests Division
3216 3210 Rivers Division
4394 (null) Newface cosmetics
3842 (null) Institute of Business Services
3843 3842 Marketing Services
3844 3842 Financial Services

Hierarchical af:tree

This details the steps to setup an ADF BC layer and ADF Faces RC bindings to support the af:tree with hierachical data from the organisations table, as previously described in Chandu Bhavsar post.

Note the following steps are well documented on Chandu's post, though you will find slightly more detail on creating the correct bindings below:

1) Create a Fusion Web App with an ADF BC Model project and ADF Faces RC ViewController.

Model project

2) In the Model project create an empty Application Module (AM)

3) Create an Entity Object (EO) based on your organisations table in the database.

4) Create two View Objects (VO) based off the same EM. Name the first ParentOrgView and the second LeafOrgView.

5) Modify the ParentOrgView query as follows:

SELECT Organisations.ORG_ID,
Organisations.PARENT_ORG_ID,
Organisations.NAME
FROM ORGANISATIONS Organisations
WHERE Organisations.PARENT_ORG_ID IS NULL

6) You don't need to modify the LeafOrgView query. For completeness it's described as follows:

SELECT Organisations.ORG_ID,
Organisations.PARENT_ORG_ID,
Organisations.NAME
FROM ORGANISATIONS Organisations

7) Create a VO Link between the ParentOrgView and LeafOrgView as follows:

Essentially:

ParentOrgView.OrgId = LeafOrgView.ParentOrgId

8) Create a second VO Link between the LeafOrgView to itself as follows:

Essentially:

LeafOrgView (source).OrgId = LeafOrgView (dest).ParentOrgId

9) Externalize the VOs through the AM using the following model:

Essentially:

ParentOrgView1
- LeafOrgView1
- - LeafOrgView2

ViewController project

10) In your ViewController project create a new blank JSF page called treeMashupDemo.jspx.

11) From the Data Control Palette drag the ParentOrgView onto the page as a tree. In the Edit Tree Binding you should see the following:

Note the first level of the tree has been defined as model.ParentOrgView.

12) For clarity when testing later, ensure both the OrgId and Name are included in the Display Attributes.

13) With the model.ParentOrgView node selected in the Tree Level Rules, select the green plus (+) button and select LeafOrgView:


14) With the LeafOrgView node selected in the Tree Level Rules, ensure both the OrgId and Name are included in the Display Attributes.

15) Again with the LeafOrgView node selected in the Tree Level Rules, again select the green plus (+) button, and select LeafOrgView__2:

Note how the Tree Level Rules only has 2 nodes, but to the right of each node is the child of the current node. Of specific interest in the hierarchical relationship between LeafOrgView and LeafOrgView__2.

16) For reference the JSF af:tree code is as follows:

var="node"
selectionListener="#{bindings.ParentOrgView1.treeModel.makeCurrent}"
rowSelection="single"
id="t1">

...the bindings look as follows:

..and the page def XML file as follows:

Package="view.pageDefs">

Testing

On running our web page we see the following:

Note that the tree is happily showing the hierarchical data based on our tree bindings.

Adding drag n drop to the tree

The next set of functionality we wish to add is the ability to drag and drop nodes, or in our case organisations, in the tree. This involves adding support for drag n drop to the tree, as well as behind the scenes updating the dropped organisation's parent_org_id to that of the org_id of the organisation the original was dropped on.

The inspiration of this section comes from Luc Bors blog post, with slight difference in mine some of the supporting code is further spelt out:

1) As a reminder at the moment our af:tree code looks as follows:

var="node"
selectionListener="#{bindings.ParentOrgView1.treeModel.makeCurrent}"
rowSelection="single"
id="t1">

2) We then introduce a collectionDragSource and a collectionDropTarget to support the drag and drop within the tree:

var="node"
selectionListener="#{bindings.ParentOrgView1.treeModel.makeCurrent}"
rowSelection="single"
id="t1">

modelName="DnDOrganisations"/>

modelName="DnDOrganisations"
dropListener="#{treeBean.dragAndDrop}"/>

Note both support the MOVE action, they both specify a matching modelName DnDOrganisations, and finally the dropListener maps to a backing bean method we'll define in a moment. It's essential the modelName's match including the case of the name, and we'll be referring to this in the dragAndDrop backing bean treeBean method in a moment.

3) In your adfc-config.xml file declare a bean treeBean of class view.TreeBean:


4) And create a Java class TreeBean in your view package within the ViewController project.

package view;

public class TreeBean {

}

The real work for drag and drop is done in the backing bean method. However in order for the code to work there are a couple of items we need to configure in the Model project:

5) Create an AppModuleImpl for the AM

6) Create a LeafOrgViewImpl for the VO

7) Create a LeafOrgViewRowImpl for the VO and ensure to include the accessors

8) In the AM expose the LeafOrgView VO one more time as its own node (not a child), and call the usage LeafOrgViewAll as follows:


9) Finally the dragAndDrop code is as follows. Note the code includes inline documentation comments that explains what is occurring:

package view;

import model.AppModuleImpl;
import model.LeafOrgViewImpl;
import model.LeafOrgViewRowImpl;
import model.ParentOrgViewRowImpl;
import oracle.adf.model.BindingContext;
import oracle.adf.view.rich.component.rich.data.RichTree;
import oracle.adf.view.rich.datatransfer.DataFlavor;
import oracle.adf.view.rich.datatransfer.Transferable;
import oracle.adf.view.rich.dnd.DnDAction;
import oracle.adf.view.rich.event.DropEvent;
import oracle.adfinternal.view.faces.model.binding.FacesCtrlHierNodeBinding;
import oracle.jbo.Key;
import oracle.jbo.uicli.binding.JUCtrlHierNodeBinding;
import org.apache.myfaces.trinidad.model.CollectionModel;
import org.apache.myfaces.trinidad.model.RowKeySet;

public class TreeBean {

public DnDAction dragAndDrop(DropEvent dropEvent) {
// The default action - do nothing
DnDAction result = DnDAction.NONE;

// Represents the object that was dropped
Transferable draggedTransferObject = dropEvent.getTransferable();

// The data in the draggedTransferObject "Transferrable" object is the row key for the dragged component.
// Note how the DnDOrganisations value in the call to getDataFlavor() matches the collectionDragSource
// and collectionDropTarget tags model attributes in our page. It's essential the strings exactly match.
DataFlavor draggedRowKeySetFlavor = DataFlavor.getDataFlavor(RowKeySet.class, "DnDOrganisations");
RowKeySet draggedRowKeySet = draggedTransferObject.getData(draggedRowKeySetFlavor);

if (draggedRowKeySet != null) {
// We grab the tree's data model, essentially the CollectionModel that stores the complete tree of nodes
CollectionModel treeModel = draggedTransferObject.getData(CollectionModel.class);

// Ask the collection model to set the current row/node to that of the transferrable object that was dropped
Object draggedKey = draggedRowKeySet.iterator().next();
treeModel.setRowKey(draggedKey);

// Grab that current row (thanks to the last statements work) and get the row's OrgId. It's essential the
// OrgId is one of the displayed attributes in the tree binding.
FacesCtrlHierNodeBinding draggedTreeNode = (FacesCtrlHierNodeBinding)treeModel.getRowData();
oracle.jbo.domain.Number draggedTreeNodeId = (oracle.jbo.domain.Number)draggedTreeNode.getAttribute("OrgId");

// The dropEvent carries the target/location's row key where the dropped organisations was dropped
Object serverRowKey = dropEvent.getDropSite();
RichTree richTree = (RichTree)dropEvent.getDropComponent();
// This time we use the tree itself to make it's current row that of the server row key (ie. the destination)
richTree.setRowKey(serverRowKey);
// And we retrieve that row's index
int rowIndex = richTree.getRowIndex();

// The rich tree based on the index allows us to retrieve that current row/organisation's OrgId
oracle.jbo.domain.Number targetNodeId = (oracle.jbo.domain.Number)((JUCtrlHierNodeBinding)richTree.getRowData(rowIndex)).getAttribute("OrgId");

// At this point we now have the OrgId of the dropped organisation (draggedTreeNodeId) and the OrgId of the
// organisation that is the target. From here we simply want to update the dropped organisations' ParentOrgId
// to the OrgId of the target. This is best done through the model layer.
//
// Normally this would be best done by fetching the appropriate iterator bindings and making the changes through
// the bindings. However in this case the tree doesn't expose any iterator for the leaf nodes, so we need to
// resort to retrieve the Model project's objects and do the work ourself.

// Retrieve the AM and then a handle on the LeafOrgViewAll - this gives us access to all rows regardless of
// where they exist in the hierarchy
AppModuleImpl am = (AppModuleImpl)BindingContext.getCurrent().getDefaultDataControl().getApplicationModule();
LeafOrgViewImpl leafOrgView = (LeafOrgViewImpl)am.getLeafOrgViewAll();

// Given the dragged organisation's OrgId, construct a key object, and then retrieve that row from the VO using
// the key
Object[] nodeObjectKey = new Object[] {draggedTreeNodeId};
Key nodeKey = new Key(nodeObjectKey);
LeafOrgViewRowImpl nodeRow = (LeafOrgViewRowImpl)leafOrgView.getRow(nodeKey);

// See below
boolean parentNode = nodeRow.getParentOrgId() == null;

// Finally update that organisaiton's ParentOrgId to that of the target organisation's OrgId
nodeRow.setParentOrgId(targetNodeId);

// And commit the changes – obviously this has side effects on any other uncommitted data, be careful
am.getDBTransaction().commit();

// If we've moved a parent node to become a leaf, we need to force the parent VO to requery itself to correctly
// reflect the data change. This is destructive on the current expand/collapsed state of the tree.
// I'm not overly sure of a solution for this; maybe a reader can suggest one.
if (parentNode) {
am.getParentOrgView1().clearCache();
am.getParentOrgView1().executeQuery();
}

// Indicate to the dragEvent that the operation was succesful and visually the move should occur in the tree
result = DnDAction.MOVE;
}
return result;
}
}

You'll note in the code I take pains to mention it's essential the OrgId is one of the displayed attributes for the tree. If you fail to supply this the routine has no OrgId attribute to fetch the OrgId value from.

This does pose a problem, because while during testing it's fine to show the OrgId and Name of the organisations in the tree, for production we might not want to show these meaningless internal ID numbers to the user. The simple fix for this is to return to the af:tree and update the af:outputText component who is responsible for what values to show for each node in the tree, changing the EL expression from #{code} to #{code.Name}:

var="node"
selectionListener="#{bindings.ParentOrgView1.treeModel.makeCurrent}"
rowSelection="single"
id="t1">

modelName="DnDOrganisations"/>

modelName="DnDOrganisations"
dropListener="#{treeBean.dragAndDrop}"/>

This ensures only the name attribute is displayed:

Read the original blog entry...