Enabling LOVs for Dynamic ViewObject attributes

In one of my previous posts, I talked about the model driven approaches for building dynamic User Interfaces. This post is in continuation of the earlier post. This time, I'll discuss about building 'Dynamic Form' containing LOV(List of Values) enabled fields (built using dynamic ViewObject).

Defining Dynamic Entity Objects and View Objects

First step is to to build EntityObject and corresponding ViewObject dynamically, based on the meta-data supplied by the run time. Below given sample code illustrates the APIs used for building EntityObjects and corresponding ViewObject, on the fly.

EntityDefImpl newEntity = new EntityDefImpl(DYNAMIC_EO);
AttributeDefImpl newAttrDef1 =
    newEntity.addAttribute("DepartmentId", "DEPARTMENT_ID",
               Number.class, false, false, true);
//Other attribute defn goes here...
newEntity.resolveDefObject();
newEntity.registerDefObject();
ViewDefImpl newView = new ViewDefImpl(DYNAMIC_VO);
newView.addEntityUsage("e", DYNAMIC_EO, false, false);
newView.addAllEntityAttributes("e");
newView.setFetchSize((short)30);

newView.setSelectClauseFlags(ViewDefImpl.CLAUSE_GENERATE_RT);
newView.setWhereClauseFlags(ViewDefImpl.CLAUSE_GENERATE_RT);
newView.setFromClauseFlags(ViewDefImpl.CLAUSE_GENERATE_RT);
buildLOVForDepartmentId(newView);

Enabling LOVs for Dynamic ViewObject attributes

Cool...Next step is to define LOV for desired attributes programmatically. Apparently, you may need to have following two items defined on the ViewObject to enable LOV for specific attributes.

1. ViewAccessor definition - For accessing Data Source View Object(destination view object) for LOV.
2. ListBinding definition - This defines meta data used for the LOV, such as the columns displayed on the LOV component, return attribute mappings etc.

The following sample code illustrates programmatic definition of LOV for 'DepartmentId' attribute.

private void buildLOVForDepartmentId(ViewDefImpl newEmpViewDef) {
  String viewAccessorName = "DepartmentIdVA";
  String lovName = "LOV_DepartmentId";
  String listDataSourceViewDefName = "model.DepartmentsView";

  ViewAccessorDef vdef = new ViewAccessorDef();
  vdef.setName(viewAccessorName);
  vdef.setViewDefFullName(listDataSourceViewDefName);
  vdef.setRowLevelBinds(true);

  newEmpViewDef.addViewAccessorDef(vdef);

  ListBindingDef listBindingDef =
    buildListBindingDef(newEmpViewDef.getDefManager(),
    viewAccessorName, lovName,
    new String[] { "DepartmentId" },
    new String[] { "DepartmentId" },
    new String[] { "DepartmentName" });
  newEmpViewDef.addListBindingDef(listBindingDef);
  int clmnIndex = newEmpViewDef.getAttributeIndexOf("DepartmentId");
  AttributeDefImpl _voAttrDef =
  (AttributeDefImpl)newEmpViewDef.getAttributeDef(clmnIndex);
  _voAttrDef.setLOVName(lovName);
  _voAttrDef.setProperty(AttributeHints.ATTRIBUTE_CTL_TYPE,
       AttributeHints.CTL_COMBO_BOX_LOV);
       /**CTLTYPE_COMBO giving ClassCastException when used in af:query*/
  }

Build the User Interface

Our model is in place, now you may need to wire the model with <dynamic:form> as shown below.

You can download the sample workspace from here.
[Runs with Oracle JDeveloper 11g R1 PS2 + HR Schema]

How to run this sample?

Run the main.jspx. Main page display a drop down list. Select the 'Employee' item from the list, and then click on the action button displayed below. This action invokes 'dynamicEntityBased-tf' task flow. The default activity for this task flow is to set up the required ViewObjects used by the view. As the next step in the sequence, control moves to 'dynamicForm' page and data is being rendered using <dynamic:form> component. This UI is generated on the fly based on the item selected from the drop down. Please check out the 'dynamicEntityBases-tf' task flow to understand the underlying execution path.


Learn More ...

There are a lot more points like this. If  you are curious to learn the internals of the ADF Business Components and ADF Binding Layer,  the following book is for you - Oracle ADF Real World Developer’s Guide.
More details about this book can be found in this post- http://jobinesh.blogspot.in/2012/07/pre-order-your-copy-of-oracle-adf-real.html