Business Rules/Logic

Field samples, multi value filters, and search bar auto complete entries display up to 200 related lookup items.

Let’s change the maximum number of lookup items displayed for Supplier Company Name of Products controller.

Start the web application generator. Click on the project name, and select Develop option. Visual Studio will start.

In the Solution Explorer, right-click 0n ~\App_Code folder, and select Add New Item.

Select Class item from the list, and press Add.

Replace the entire sample content of the file with the following:

C#:

using System;
using System.Web;
namespace MyCompany.Data
{
    public partial class DistinctValueRequest
    {
        public override int MaximumValueCount
        {
            get
            {
                if (Controller == "Products")
                {
                    if (FieldName == "SupplierCompanyName")
                        return 10;
                    else
                        return 20;
                }
                return base.MaximumValueCount;
            }
            set
            {
                base.MaximumValueCount = value;
            }
        }
    }
}

Imports Microsoft.VisualBasic
Imports System
Imports System.Web

Namespace MyCompany.Data
    Partial Public Class DistinctValueRequest
        Public Overrides Property MaximumValueCount As Integer
            Get
                If Controller = "Products" Then
                    If FieldName = "SupplierCompanyName" Then
                        Return 10
                    Else
                        Return 20
                    End If
                End If
                Return MyBase.MaximumValueCount
            End Get
            Set(value As Integer)
                MyBase.MaximumValueCount = value
            End Set
        End Property
    End Class
End Namespace

This class will instruct the application framework to use 20 distinct value samples for all fields in the Products controller with the exception of Supplier Company Name. The limit for Supplier Company Name is 10. No other controllers will be affected.

Save the class. On the keyboard, press Ctrl+F5 to start the web application. Navigate to the Products page.

Activate the Supplier Company Name header dropdown. Only the first 10 items will be available for selection.

Open the advanced search bar, and activate the Auto Complete dropdown for Supplier Company Name. Only 10 items will be displayed at one time.

The Multi Value Filter window will only display 10 items.

Other fields in the Products controller will display 20 distinct value samples, such as the Quantity Per Unit header dropdown.

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.