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Overview
This tutorial steps you through the development of a data
model for an order entry application.
You have been given the task of creating a data model to support
an Order Entry application. The data model must contain logic that supports
the rules of the business. Because the rules are enforced inside the data model,
all client applications that use the model will always follow the basic rules
of the business. You will build these rules using Orace ADF Business Components.
In this step you will create a new application workspace
and project to help organize your application. All of the work you do in JDeveloper
is organized into projects within an application workspace. After you have created
a workspace and project, you will create a default Business Components Model
for your business.
Create a new Application workspace to hold the business model components.
Select File | New, then select the Application workspace
node.
Click OK.
This will open a dialog where you can define location, templates, and
application package prefix
2.
Change the name of the application to OEApplication. Accept the other
defaults for the application and click OK.
3.
On completion you should have an application named OEApplication
and two projects named Model and ViewController. You will
only use the Model project for this exercise.
It is generally easier and more effective to start
with a set of default business components than to create each one individually.
Whichever technique you use will result in a set of components that you
can customize to fit your specific business needs.
To create a set of default business components, right-click the Model
project node in the System Navigator and select New.
2.
This opens the New Gallery wizard. From this gallery, select the Business
Components category and Business Components from Tables.
3.
Selecting Business Components from Tables opens the Business Components
wizard. The first step of this wizard is to establish a connection to
your database. Select the connection name that connects to the OE schema.
Note: If you have not established this connection to the OE schema, please
see the prerequisites section.
4.
In step 1 of the Business Component wizard, select the tables for which
you want to create entity objects. Select the Customers, Inventories,
Orders, OrderItems, ProductDescriptions, and ProductInformation
tables.
5.
In step 2 of the wizard, select which view objects you want to create
from the default entity objects just selected. Select all of the available
entity objects and click the shuttle button.
6.
In step 3 of the wizard, change the name of the Application Module to
OEAppModule. If the Application Module checkbox is checked, the
wizard will create a default application module for you.
If it is not checked, check it.
7.
The last step of the wizard confirms what Business Component objects
you are about to create.
8.
Your project should now include an application module with entity and
view objects.
JDeveloper includes a built-in Business Components
Browser that tests business components. The browser works without requiring
you to build any client code.
To invoke the tester, right-click the Application Module you just created
in the System Navigator and select Test from the context
menu.
2.
The first step of the Tester is to select a database connection to use
for this test. Select the database connection you used to create the default
objects and click Connect.
3.
The Business Components Browser shows all of the View objects defined
in your Application Module.
4.
Double-click a view object instance to display a single-record data viewer.
You can scroll through the rows in this View object using the controls
on the top of the window. You can double-click other View objects to run
multiple data viewers.
The Business Components Browser gives you a view of the application module
that you have just created.
The Business Component wizard creates a single View object
for each Entity object created. While this is useful in most cases, you will
probably need to create a View object that combines attributes from multiple
Entity objects. For example, the OrderItemsView contains information about the
Item within an Order but does not include information about the Item, such as
a description of the item. In this step, you will add some product information
to the OrderItemsView.
1.
In the System Navigator, right-click OrderItemsView
and select Edit from the context menu
2.
Use the View Object Editor to add the ProductInformation entity
to the list of selected entities for this View object.
3.
Now that you have selected the additional entity, you need to select
the attributes you want to add. Click the Attributes node and select
ProductName and ProductDescription from the available attributes
list and shuttle them to the selected list.
4.
Click the Query node to inspect the changes that JDeveloper made
to the query. Notice that the query now includes a join to the ProductInformation
table and that it includes the two new columns.
Click OK to accept the new query.
5.
Run the Tester again only this time double-click the OrderItemsView1
view object. Notice that it now shows all of the attributes it did before
plus the new attributes ProductName and ProductDescription.
If you need help running the Tester, see Testing Business Components
in Step 1 of this tutorial.
So far, you have created some default business logic and have
expanded a view to meet your requirements. Now you need to add some validation
to the business model. In ADF Business Components, validation is done in the
business logic tier, not in the client. To validate business rules, you modify
the objects responsible for persisting data, which are entity objects.
There are two different types of validation that you can add
to the business model: Attribute-level validation and Row-level
validation. Attribute-level validation is used to check values within
a single attribute. Row-level validation is used when a value must be
checked against other attributes or entities. In this step, you will add validation
of both types to your model.
In our business, we keep track of many orders. Each order
is assigned a status code that indicates the current status of the order. There
is a list of valid codes, but the numbers range from 0 to 10. In this step,
we will add a validator that will make sure that only values in that range are
entered.
In the System Navigator, right-click the Orders
entity and choose Edit Orders.
2.
In the Entity Object Editor, click the Validation node. The Editor
now shows the entity and all of the attributes.
3.
Select the OrderStatus attribute and click New. This will
launch the Validation Rule editor for the OrderStatus attribute.
4.
In the Validation Rule Editor, select the RangeValidator rule
and the Between operator. Enter a 0 (zero) in the Minimum Value
and a 10 (ten) in the Maximum Value. Enter a message in the Error Message
field that will help a user correct the error if they enter an invalid
status.
Click Ok to accept the new rule.
5.
After accepting the rule you that just created, you can continue to create
additional attribute-level rules.
When you are done with the attribute-level rules, click OK.
6.
Now that you have added a rule, it's time to test it. You test the rule
by running the Business Components Browser.
Right-click the application module and select Test
from the context menu, just as you did earlier.
7.
Double-click the OrdersView1 node to open the OrdersView window.
8.
Try to modify the OrderStatus to a value that is not in the valid
range (0-10). Notice that when you enter a value that is outside the range,
ADF Business Components raises an exception that includes the error message
you entered on the validation rule.
When you are finished testing the rule, close the Tester.
Adding Row-level Validation
The next business rule you will add to the model is a rather
simple rule. The rule is that customers cannot order items that we don't have
in stock. In other words, we don't allow backorders. Although the rule is simple
enough, it will take a little code to enforce the rule. ADF Business Components
provides hooks and accessor methods that make it easy to implement.
In this section, you will add some validation code and add
a new validation rule to the OrderItems entity. We provide the code for you
to make it a little easier for you.
Click the OrderItems entity in the System Navigator. The Structure
pane now displays all of the components that are part of the entity.
2.
OrderItemsImpl.java is
the java class that you will use to validate row level data.
Double-click OrderItemsImpl.java to edit the implementation class
for the OrderItems entity. This will open the java file in the editor
window.
3.
Add the following method to the end of the class. Take a look at the
previous image to see where it goes. You can copy and paste this code
directly into the code editor.
public boolean validateOnHandQuantity
(Number ordered)
{
/** Create a RowIterator
of all the Inventories for the Product you are
* ordering. We are traversing the association from OrderItems to
* ProductInformation to Inventories. These methods are created
* automatically when the association is created.
*/
RowIterator inventoryItems = getProductInformation().getInventories();
int quantityOnHand = 0;
/** Loop through all the Inventories and sum the QuantityOnHand
*/
while (inventoryItems.hasNext())
{
InventoriesImpl inventoryItem
= (InventoriesImpl)inventoryItems.next();
int quantity = inventoryItem.getQuantityOnHand().intValue();
quantityOnHand += quantity;
}
/** Check if the ordered quantity is less than or equal to the total
onHand
*/
if (ordered.doubleValue() <= quantityOnHand)
return true;
else
return false;
}
4.
After you have added the code, right-click anywhere in the code editor
window and select Make from the context menu. This compiles
the code and checks for errors. Notice that there is an error "class
RowIterator not found". This error is because we have not added the
proper import statement to this class yet.
Notice also that in the code editor, RowIterator
is underlined in blue. JDeveloper is giving you hints on what needs to
be fixed in this class. In the next step, we'll use a JDeveloper feature
to add the proper import for this class.
5.
Move the cursor over the RowIterator
statement in the code editor. JDeveloper shows a balloon-style message
that says "Import oracle.jbo.RowIterator ( Alt + Enter)".
If you hit Alt + Enter, JDeveloper will add the import statement
for you.
Hit Alt + Enter to add the import statement.
6.
Now that you have added the import statement, compile the class again.
Right-click anywhere in the code editor and select Make
from the context menu.
This time you get a message saying that the class compiled successfully.
Now that you have a method that will validate the number of items in
stock, you can add the validation rule that will use that method.
7.
Right-click the OrderItems entity object in the System Navigator
and select Edit OrderItems. You could also double-click
the OrderItems entity to open the editor.
8.
In the Entity Object Editor, click the Validation node. The Editor
now shows the entity and all of the attributes.
9.
Select the Quantity attribute and click New to open the
Validation rule dialog and create a new rule.
10.
Select MethodValidator from the Rules drop-down list. JDeveloper
will automatically look in the Implementation class for any custom methods
that you have added. Select the one that you want to use for this rule.
In this case, there is only one method available which is validateOnHandQuantity(oracle.jbo.domain.Number
ordered.
Select that method and add a reasonable error message in the error message
field.
Click OK to accept the new rule.
Click OK to accept the changes you have made to the OrderItems
entity.
11.
Now that you have added this rule, it's time to test it. You test the
rule by running the Business Components Browser.
Right-click the application module and select Test
from the context menu, just as you did earlier.
12.
Double-click the OrdersItemsView1 node to open the OrderItemsView
window.
13.
Try to modify the Quantity to a value that is probably not in
stock (try 800). Notice that when you enter a value that is over what
is in stock, ADF Business Components raises an exception that includes
the error message you entered on the validation rule.
When you are finished testing the rule, close the Tester.
Summary
In this tutorial you learned how to use ADF Business Components
to build a model that supports your business rules. You have learned how to
add simple, declarative validation rules and how to add custom methods to validate
more complex business needs.
You have also learned how to test your business model using
the built-in ADF Business Components Tester.
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