Code On Time: business rules/logic

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business rules/logic

Monday, June 25, 2012Print Subscribe

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;
            }
        }
    }
}

Visual Basic:

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.

Labels: Business Rules/Logic, User Interface, Web Application Generator

Tuesday, June 19, 2012Print Subscribe

Capturing Current User Identity

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:

Column Name	Data Type	Allow Nulls
ModifiedByID	uniqueidentifier	True
ModifiedByName	nvarchar(50)	True

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:

Property	Value
Command Name	Insert\|Update
Name	UpdatingModifiedBy
Type	SQL
Phase	After
Script	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.

Labels: Business Rules/Logic, Security, Web Application Generator

Tuesday, June 19, 2012Print Subscribe

Value Conversion

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:

Property	Value
Command Name	Insert\|Update
Type	SQL
Phase	Before
Script	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:

Property	New Value
Command Name	Calculate

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:

Property	New Value
The value of this field is calculated by a business rule expression.	True
Context Fields	CustomerID

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.

Property	New Value
Command Name	Calculate\|Insert\|Update

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

Labels: Business Rules/Logic, Web Application Generator