Blog: Posts from February, 2013

The “When View” property allows controlling the visibility of an action based on the current view.

For example, let’s create a custom action that will display the extended price of an order detail. This action will be available on editForm1 and grid1 by default. Let’s prevent the action from being displayed on grid1 by using When View property.

Creating the Action and Business Rule

Start the Project Designer. In the Project Explorer, switch to the Controllers tab. Right-click on OrderDetails / Actions / ag3 (ActionBar) – New node, and press New Action.

Assign the following values.

Press OK to save. Right-click on OrderDetails / Business Rules node, and press New Business Rule.

Use the following configuration:

var extendedPrice = [UnitPrice] * (1 - [Discount]) * [Quantity];
alert(String.localeFormat('{0:c}', extendedPrice));

Press OK to save.

On the toolbar, press Browse. Navigate to the Order Details page. The Extended Price button will be present on the action bar. When you select a row and activate the button, the extended price will be displayed in an alert.

Select a record – the action will also be available on editForm1.

Note that the action is not available on createForm1. This is because the When Last Command Name property of the action is blank (which is equivalent to “Select”). View createForm1 is activated by triggering the “New” action, resulting in the Extended Price action being hidden.

Specifying “When View”

Let’s restrict display of the Extended Price action to editForm1 using the When View property.

In the Project Explorer, double-click on OrderDetails / Actions / ag3 (ActionBar) – New / a100 – Custom, ShowExtendedPrice | Extended Price action node.

Change the When View property:

Press OK to save.

Viewing the Results

On the toolbar, press Browse. Navigate to the Order Details page. Note that the action is no longer displayed in grid1.

Select a record. The action will be available in editForm1.

SQL business rules allow server-side code to be executed in response to certain conditions. In addition to executing anonymous SQL code blocks, business rules can also be used in order to trigger a stored procedure.

Let’s create a stored procedure in the Northwind database that will calculate the average value of Freight for a specified customer. Then, a business rule will be added that will be triggered before every Update and Insert command in the Orders controller, and will use the stored procedure to verify that the Freight does not exceed the average freight. If it does, a message will be displayed and the command will be canceled.

Creating a Stored Procedure

Start SQL Server Management Studio. In the Object Explorer, right-click on Databases / Northwind node, and press New Query.

Insert the following query:

create procedure sp_ValidateFreight
    -- inputted customer
    @CustomerID nvarchar(5),
    -- returned average freight
    @AverageFreight money output
as
begin
   select @AverageFreight = AVG(Freight) 
   from Orders
   where CustomerID = @CustomerID
end
go

On the toolbar, press Execute to create the stored procedure.

Adding the Business Rule

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

Assign the following values:

declare @AvgFreightOfOrders money
-- execute stored procedure
exec sp_ValidateFreight @CustomerID,
    @AverageFreight = @AvgFreightOfOrders output
-- check the freight
if @AvgFreightOfOrders is not null 
    and @AvgFreightOfOrders < @Freight 
begin
    -- prevent actual Update or Insert from happening
    set @BusinessRules_PreventDefault = 1 
    -- show an alert next to the Freight field
    set @Result_Focus = 'Freight,The freight exceeds the average' 
    + ' of $' + CONVERT(varchar(12), @AvgFreightOfOrders, 1) 
    + ' of previous orders.'
end

Press OK to save the business rule.

Viewing the Results

On the toolbar, press Browse. When generation is complete, navigate to the Customers page, select a customer, and create a new order. Enter a very high value for Freight, and save the record. The save will be canceled and a message will be displayed next to Freight.

Enter a value below the displayed average and press OK. The order will be saved.