Blog: Posts from June, 2012

Many applications require that the name and identity of the user be captured when a record is modified. Let’s create a ModifiedByID and ModifiedByName field in the Orders table that will be updated by an SQL Business Rule whenever an order is modified.

First, let’s add the columns to the table. Start SQL Server Management Studio. In the Object Explorer, right-click on Databases / Northwind / Tables / dbo.Orders table node, and select Design.

Configure two new columns:

Save the table modifications. Switch to the web application generator, and refresh the Orders controller.

Regenerate the web application. Next, let’s remove the ModifiedBy fields from the presentation, and create a business rule to update these fields.

Start the Project Designer. In the Project Explorer, switch to the Controllers tab. Right-click on Orders / Views / editForm1 / c1 – Orders / ModifiedByUserID data field node, and select Delete option.

Confirm the operation. Right-click on Orders / Views / editForm1 / c1 – Orders / ModifiedByUserName data field node, and delete this data field as well.

Right-click on Orders / Business Rules node, and select New Business Rule.

Assign this business rule the following properties:

update Orders 
set ModifiedByUserID = @BusinessRules_UserId, 
    ModifiedByUserName = @BusinessRules_UserName
where OrderID = @OrderID

Press OK to save the business rule.

Make sure to spell the business rule properties correctly – for example, if the “@BusinessRules_UserId” function was capitalized as “@BusinessRules_UserID”, the function will not be found and an exception will be thrown.

On the toolbar, press Browse to regenerate the web application.

Navigate to the Orders page, edit a record, and save.

View the record in SQL Server Management Studio. The relevant UserId and Name have been saved.

Project requirements may dictate that conversion should be performed on field values.

For example, the Customer# field of the Customers table in the Northwind database may need to be converted to uppercase.

However, there is no mechanism preventing users from saving lowercase letters in the field.

Let’s create an SQL Business Rule to perform field value conversion.

Validate on Insert or Update

Start the Project Designer. In the Project Explorer, switch to the Controllers tab. Right-click on Customers / Business Rules node, and select New Business Rule.

Use the following properties:

set @CustomerID = UPPER(@CustomerID)

Press OK to save the business rule. On the toolbar, press Browse.

Navigate to the Customers page, and edit a record. Insert some mixed-case letters in the Customer# field.

Save the record. The field value will be converted to uppercase.

Validate on Calculate

You can also perform just-in-time value conversion, when the user moves focus away from the field.

Switch back to the Project Designer. In the Project Explorer, double-click on Customers / Business Rule / Insert|Update node.

Change the Command Name property:

Press OK to save the business rule. In order for the calculation to be performed, the field needs to cause a server request.

In the Project Explorer, double-click on Customers / Fields / CustomerID field node.

Make the following changes:

Press OK to save the field. On the toolbar, press Browse.

On the Customers page, edit a record. Insert mixed-case characters into the Customer# field.

Press Tab on your keyboard or click on another field. The client library will convert the value in Customer# field into uppercase.

Expanding the Business Rule

The user may still click on the OK button and save the lowercase characters in the field. Therefore, you may need to combine both Insert|Update and Calculate command handling. The following Command Name will cover all possible methods of changing the field.

The same business logic can be implemented with the help of C#/Visual Basic Business Rules.