Thursday Dec 29, 2011

Business Rules Editor for View Objects in JDeveloper

JDeveloper has a new tab in the View Objects Editor - Business Rules.
This easily tend to make people misunderstand that this Editor can be used for adding validation rules for the attributes in the View Object. However, it is not true.

Lets check out what this editor is all about. As the online help for this page states
Use to create and maintain business rules based on Groovy Language expressions and declarative validation rules for this view object including:

  • Validators for transient attributes
  • Bind variable default value expressions for SQL queries
  • Bind variable value mappings for view accessors
  • Transient attribute value expressions
  • Transient attribute value expression recalculation conditions
  • Attribute default value expressions

We'll see how we can use this editor to edit different types :

Transient Attributes : 

We can use this editor for a. adding validation rules, b. edit default value expression

a. As like the Entity Attributes, we can add many validation rules for the transient attributes in VO as well.


In the above image, EmpType is a transient attribute on Emp VO.We can see there are two rules added. First one is a validation rule (List Validator), restricting the user to enter either one of the value specified for the attribute. Second one is the default value expression for the attribute. Upon selecting the node, the default value groovy expression would become editable in the Script Expression field below, wherein we can modify it and test the syntax as well.

Note : We can add the validation rule only for the transient attributes which are Updatable. Also, we can edit only the default values which are script expressions only. Not the literal values.

Bind Variables :

Similar to the transient attributes, we can use this editor for modifying and testing the default value expression for the Bind Variables of the VO as well.

Ex :

In the above example image, we can see a Bind Variable (Bind_Hiredate) added to the Query, which has the default value expression as adf.currentDate.

Using this editor, we can modify this expression and test the syntax.

View Accessor :

If we have a bind variable to the VO and use it as List Data Source for any of the attributes in the VO, we can use this editor to change the value of the bind variable in the View Accessor.

Ex :

In the above example image, we have couple of Bind Variables in the View Accessors (they are used as Lists and Dependent Lists for this View Object). Using this editor, we can edit the values of those bind variables.

We can also use this editor for modifying and testing the default value expression on the VO attributes and the re-calculation conditions.

Monday Nov 28, 2011

Creating Custom validation rule and register it

What is Validation Rule?

A validation rule is a piece of code that performs some check ensuring that data meets given constraints.

In an enterprise application development environment, often it might require developers to have validation be performed based on some logic at several places across projects. Instead of redundant validation creation, a custom validation rule provides a library with a validation rules that can be registered and used across applications.
A custom Validation is encapsulated in a reusable component so that you do not have to write it every time when you need to do input validation.

Here is how we can easily implement a custom validation that checks for name of an employee to be "KING"

For creating a custom Validation ,

1.         Create Generic Application Workspace "CustomValidator" with the project "Model"

2.         Create an BC4J based on emp table.

3.         Create a custom validation rule.


In EmpNamerule class, update the validateValue(..) method as follows: 

public boolean validateValue(Object value) { 
        EntityImpl emp = (EntityImpl)value; 
            return false; 
        return true; 

Create ADF Library: Next step would be to create ADF library.

Create ADF library with name lets say testADFLibrary1.jar

Register ADF Library
Next step is to register the ADF library , so that its available across the applications.

Invoke the menu "Tools -> Preferences"
Select the option "Business Components -> Registered Rules" from left pane
Click on button "Pick Library". The dialog "Select Library" comes up with  the user library added
Add new library' that points to the above jar
Check the checkbox "Register" and set the name for the rule


Sample Usage

Here is how we can easily implement a validation rule that restrict the name of the employee not to be "KING".
Create new Application with BC4J based on EMP table.
Create new validation under Business rule tab for Ename & select the above custom validation rule.
Run the AppModule tester.



Tips and Tricks from Oracle's JDeveloper & ADF QA


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