Business Rules/Logic

The Code Value property is a calculation performed every time the record is inserted or updated. The calculation expression is written in the programming language of your project – Visual Basic or C#.

For example, let’s keep track of the last time an order detail was modified.

Start SQL Server Management Studio. In the Object Explorer, right-click on Databases / Northwind / Tables / dbo.OrderDetails node and select Design.

Add a column to the table:

Save the table. Switch back to the application generator and refresh the Order Details controller.

Activate the Project Designer. In the Project Explorer, switch to the Controllers tab. Double-click on OrderDetails / Views / editForm1 / c1 – Order Details / ModifiedOn data field node.

Change the following properties:

Press OK to save the data field. Double-click on OrderDetails / Fields / ModifiedOn node.

Change the following properties:

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

Navigate to the Order Details page, and edit a record. The Modified On field has no value.

Change any field value in the record, and save. Open the detail view for the same record – the Modified On field value has been updated.

The field will update on every insert or update.

The web application generator has placed the Code Value formula in an automatically generated business rule associated with the data controller.

C#:

using System;
using System.Data;
using System.Collections.Generic;
using System.Linq;
using System.Text.RegularExpressions;
using System.Web;
using System.Web.Security;
using MyCompany.Data;

namespace MyCompany.Rules
{
    public partial class OrderDetailsBusinessRules : MyCompany.Data.BusinessRules
    {
        
        [ControllerAction("OrderDetails", "Insert", ActionPhase.Before)]
        [ControllerAction("OrderDetails", "Update", ActionPhase.Before)]
        public void AssignFieldValuesToOrderDetails(int? orderID, 
            string orderCustomerID, string orderCustomerCompanyName, 
            string orderEmployeeLastName, string orderShipViaCompanyName, 
            int? productID, string productProductName, 
            string productCategoryCategoryName, string productSupplierCompanyName, 
            decimal? unitPrice, short? quantity, float? discount, DateTime? modifiedOn)
        {
            FieldValue ModifiedOnFieldValue = SelectFieldValueObject("ModifiedOn");
            object ModifiedOnCodeValue = DateTime.Now;
            if (ModifiedOnFieldValue == null)
                AddFieldValue("ModifiedOn", ModifiedOnCodeValue);
            else
            {
                ModifiedOnFieldValue.NewValue = ModifiedOnCodeValue;
                ModifiedOnFieldValue.Modified = true;
                ModifiedOnFieldValue.ReadOnly = false;
            }
        }
    }
}

Visual Basic:

Imports MyCompany.Data
Imports System
Imports System.Collections.Generic
Imports System.Data
Imports System.Linq
Imports System.Text.RegularExpressions
Imports System.Web
Imports System.Web.Security

Namespace MyCompany.Rules
    
    Partial Public Class OrderDetailsBusinessRules
        Inherits MyCompany.Data.BusinessRules
        
        <ControllerAction("OrderDetails", "Insert", ActionPhase.Before), _
         ControllerAction("OrderDetails", "Update", ActionPhase.Before)> _
        Public Sub AssignFieldValuesToOrderDetails(ByVal orderID As Nullable(Of Integer),
                                                   ByVal orderCustomerID As String,
                                                   ByVal orderCustomerCompanyName As String,
                                                   ByVal orderEmployeeLastName As String,
                                                   ByVal orderShipViaCompanyName As String,
                                                   ByVal productID As Nullable(Of Integer),
                                                   ByVal productProductName As String,
                                                   ByVal productCategoryCategoryName As String,
                                                   ByVal productSupplierCompanyName As String,
                                                   ByVal unitPrice As Nullable(Of Decimal),
                                                   ByVal quantity As Nullable(Of Short),
                                                   ByVal discount As Nullable(Of Single),
                                                   ByVal modifiedOn As Nullable(Of DateTime))
            Dim ModifiedOnFieldValue As FieldValue = SelectFieldValueObject("ModifiedOn")
            Dim ModifiedOnCodeValue As Object = DateTime.Now
            If (ModifiedOnFieldValue Is Nothing) Then
                AddFieldValue("ModifiedOn", ModifiedOnCodeValue)
            Else
                ModifiedOnFieldValue.NewValue = ModifiedOnCodeValue
                ModifiedOnFieldValue.Modified = True
                ModifiedOnFieldValue.ReadOnly = False
            End If
        End Sub
    End Class
End Namespace

This can also be done with SQL Business Rules.

The application framework of each project is generated in C# or Visual Basic. The business rules engine of the framework takes care of executing SQL, Email, and JavaScript business rules in response to actions defined in the data controller. Naturally, developers can create business rules written in the programming language of the project to tap in the power of the business rules engine and vast Microsoft.NET library.

For example, the “Code” business rule defined in the project configuration will result in the code file generated in the project output folders.

The business rule file provides a method template linked to the data controller business rule with Rule attribute. The file will not be re-created during subsequent code generation sessions. Any modifications to the file will become a permanent extension of the application framework.

Let’s implement a validation business logic.  Note that the highlighted text indicates the conditional expression inserted in the automatically generated business rule method template.

C#:

using System;
using MyCompany.Data;

namespace MyCompany.Rules
{
    public partial class CustomersBusinessRules : MyCompany.Data.BusinessRules
    {
        /// <summary>
        /// This method will execute in any view before an action
        /// with a command name that matches "Insert|Update|Delete".
        /// </summary>
        [Rule("r100")]
        public void r100Implementation(string customerID, string companyName,
            string contactName, string contactTitle, string address, string city,
            string region, string postalCode, string country, string phone, string fax)
        {
            // This is the placeholder for method implementation.
            if (country == "USA")
            {
                // tell the application framework to skip the execution of update, insert, or delete
                PreventDefault();
                // set the focus to the field "Country" and display an error message
                Result.Focus("Country",
                    "You are not authorized to {0}, " +
                    "if the Country is equal to \"USA\".",
                    Arguments.CommandName.ToLower());
                // show an additional information in the message bar at the top of the page
                Result.ShowMessage("Error trying to execute {0} command",
                    Arguments.CommandName);
            }
        }
    }
}

Visual Basic:

Imports MyCompany.Data
Imports System

Namespace MyCompany.Rules
    Partial Public Class CustomersBusinessRules
        Inherits MyCompany.Data.BusinessRules
        ''' <summary>
        ''' This method will execute in any view before an action
        ''' with a command name that matches "Insert|Update|Delete".
        ''' </summary>
        <Rule("r100")> _
        Public Sub r100Implementation(ByVal customerID As String, ByVal companyName As String,
            ByVal contactName As String, ByVal contactTitle As String, ByVal address As String,
            ByVal city As String, ByVal region As String, ByVal postalCode As String,
            ByVal country As String, ByVal phone As String, ByVal fax As String)
            ' This is the placeholder for method implementation.
            If (country = "USA") Then
                ' tell the application framework to skip the execution of update, insert, or delete
                PreventDefault()
                ' set the focus to the field "Country" and display an error message
                Result.Focus("Country",
                    "You are not authorized to {0}, " &
                    "if the Country is equal to ""USA"".",
                    Arguments.CommandName.ToLower())
                ' show an additional information in the message bar at the top of the page
                Result.ShowMessage("Error trying to execute {0} command",
                    Arguments.CommandName)
            End If
        End Sub
    End Class
End Namespace

The pattern of implementation is following closely the pattern of SQL and JavaScript business rules. Both of these alternatives are actually built on top of the same infrastructure demonstrated in this example.

The screenshot shows the “code” business rule in action.