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Business Rules/Logic
Tuesday, November 27, 2012PrintSubscribe
Advanced User Manager for Custom Membership and Role Provider: Implementing the Business Rules

Instead of allowing the application framework to handle the CRUD operations, let’s prevent the default behavior and implement several business rules. These business rules with use the ASP.NET Membership API to insert, update, and delete users.

Insert

In the Project Explorer, right-click on Users / Business Rules node, and press New Business Rule.

Creating a new business rule for Users data controller.

Assign the following properties:

Property Value
Type C# / Visual Basic
Command Name Insert
Phase Before

Press OK to save the business rule. On the toolbar, press Browse to regenerate the web app and create the business rule file. When finished, right-click on Users / Business Rules / Insert (Code / Before) – r101 node and press Edit Rule in Visual Studio.

'Edit Rule in Visual Studio' context menu option for a code business rule.

Replace the content of the file with the following:

C#:

using System;
using System.Web;
using System.Web.Security;
using MyCompany.Data;
using MyCompany.Security;

namespace MyCompany.Rules
{
    public partial class UsersBusinessRules : MyCompany.Data.BusinessRules
    {

        /// <summary>
        /// This method will execute in any view before an action
        /// with a command name that matches "Insert".
        /// </summary>
        [Rule("r101")]
        public void r101Implementation(
                    FieldValue userID,
                    string userName,
                    string password,
                    string email,
                    string comment,
                    string passwordQuestion,
                    string passwordAnswer,
                    bool isApproved,
                    DateTime? lastActivityDate,
                    DateTime? lastLoginDate,
                    DateTime? lastPasswordChangedDate,
                    DateTime? creationDate,
                    bool? isLockedOut,
                    DateTime? lastLockedOutDate,
                    int? failedPasswordAttemptCount,
                    DateTime? failedPasswordAttemptWindowStart,
                    int? failedPasswordAnswerAttemptCount,
                    DateTime? failedPasswordAnswerAttemptWindowStart,
                    string roles,
                    string confirmPassword,
                    int? roleID)
        {
            // prevent execution of CRUD operations by the application framework
            PreventDefault();
            // ensure that "Password" and "ConfirmPassword" match
            if (password != confirmPassword)
                throw new Exception(Localize("PasswordAndConfirmationDoNotMatch",
                    "Password and confirmation do not match"));
            // create a user with the Membership API
            MembershipCreateStatus status;
            MembershipUser newUser = Membership.CreateUser(userName, password, email, 
                passwordQuestion, passwordAnswer, isApproved, out status);
            // analyze and report any errors
            if (status != MembershipCreateStatus.Success)
            {
                string error = null;
                switch (status)
                {
                    case MembershipCreateStatus.DuplicateEmail:
                        error = "Duplicate email address.";
                        break;
                    case MembershipCreateStatus.DuplicateProviderUserKey:
                        error = "Duplicate provider key";
                        break;
                    case MembershipCreateStatus.DuplicateUserName:
                        error = "Duplicate user name.";
                        break;
                    case MembershipCreateStatus.InvalidAnswer:
                        error = "Invalid password recovery answer.";
                        break;
                    case MembershipCreateStatus.InvalidEmail:
                        error = "Invalid email address.";
                        break;
                    case MembershipCreateStatus.InvalidPassword:
                        error = string.Format("Invalid password. Requires at least {0} " +
                            "characters and {1} non-alphanumeric characters.",
                            Membership.Provider.MinRequiredPasswordLength,
                            Membership.Provider.MinRequiredNonAlphanumericCharacters);
                        break;
                    case MembershipCreateStatus.InvalidProviderUserKey:
                        error = "Invalid provider user key.";
                        break;
                    case MembershipCreateStatus.InvalidQuestion:
                        error = "Invalid password recovery question.";
                        break;
                    case MembershipCreateStatus.InvalidUserName:
                        error = "Invalid user name.";
                        break;
                    case MembershipCreateStatus.ProviderError:
                        error = "Provider error.";
                        break;
                    case MembershipCreateStatus.UserRejected:
                        error = "User has been rejected.";
                        break;
                }
                throw new Exception(error);
            }
            // assign "Comment" to the new user
            if (!(String.IsNullOrEmpty(comment)))
            {
                newUser.Comment = comment;
                Membership.UpdateUser(newUser);
            }
            // assign "Roles" to the new user
            if (!(String.IsNullOrEmpty(roles)))
            {
                string[] newRoles = Convert.ToString(roles).Split(',');
                foreach (string role in newRoles)
                    if (!(String.IsNullOrEmpty(role)))
                        System.Web.Security.Roles.AddUserToRole(
                            userName, role);
            }
        }
    }
}

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 UsersBusinessRules
        Inherits MyCompany.Data.BusinessRules

        ''' <summary>
        ''' This method will execute in any view before an action
        ''' with a command name that matches "Insert".
        ''' </summary>
        <Rule("r101")> _
        Public Sub r101Implementation( _
                    ByVal userID As FieldValue, _
                    ByVal userName As String, _
                    ByVal password As String, _
                    ByVal email As String, _
                    ByVal comment As String, _
                    ByVal passwordQuestion As String, _
                    ByVal passwordAnswer As String, _
                    ByVal isApproved As Nullable(Of Boolean),
                    ByVal isLockedOut As Nullable(Of Boolean), _
                    ByVal roles As String, _
                    ByVal confirmPassword As String)
            ' prevent execution of CRUD operations by the application framework
            PreventDefault()
            ' ensure that "Password" and "ConfirmPassword" match
            If (password <> confirmPassword) Then
                Throw New Exception(Localize("PasswordAndConfirmationDoNotMatch",
                                             "Password and confirmation do not match"))
            End If
            Dim status As MembershipCreateStatus
            ' create a user with the Membership API
            Dim newUser As MembershipUser = Membership.CreateUser(userName,
                                  password,
                                  email,
                                  passwordQuestion,
                                  passwordAnswer,
                                  isApproved,
                                  status)
            ' analyze and report any errors
            If (status <> MembershipCreateStatus.Success) Then
                Dim [error] As String = ""
                Select Case status
                    Case MembershipCreateStatus.DuplicateEmail
                        [error] = "Duplicate email address."
                    Case MembershipCreateStatus.DuplicateProviderUserKey
                        [error] = "Duplicate provider key"
                    Case MembershipCreateStatus.DuplicateUserName
                        [error] = "Duplicate user name."
                    Case MembershipCreateStatus.InvalidAnswer
                        [error] = "Invalid password recovery answer."
                    Case MembershipCreateStatus.InvalidEmail
                        [error] = "Invalid email address."
                    Case MembershipCreateStatus.InvalidPassword
                        [error] = String.Format("Invalid password. Requires at least {0} " +
                            "characters and {1} non-alphanumeric characters.",
                            Membership.Provider.MinRequiredPasswordLength,
                            Membership.Provider.MinRequiredNonAlphanumericCharacters)
                    Case MembershipCreateStatus.InvalidProviderUserKey
                        [error] = "Invalid provider user key."
                    Case MembershipCreateStatus.InvalidQuestion
                        [error] = "Invalid password recovery question."
                    Case MembershipCreateStatus.InvalidUserName
                        [error] = "Invalid user name."
                    Case MembershipCreateStatus.ProviderError
                        [error] = "Provider error."
                    Case MembershipCreateStatus.UserRejected
                        [error] = "User has been rejected."
                End Select
                Throw New Exception([error])
            End If
            ' assign "Comment" to the new user
            If (Not (String.IsNullOrEmpty(comment))) Then
                newUser.Comment = comment
                Membership.UpdateUser(newUser)
            End If
            ' assign "Roles" to the new user
            If (Not String.IsNullOrEmpty(roles)) Then
                Dim newRoles() As String = Convert.ToString(roles).Split(",")
                For Each role As String In newRoles
                    If (Not String.IsNullOrEmpty(role)) Then
                        System.Web.Security.Roles.AddUserToRole(userName, role)
                    End If
                Next

            End If
        End Sub
    End Class
End Namespace

Save the file.

Update

Create another business rule with the following properties:

Property Value
Type C# / Visual Basic
Command Name Update
Phase Before

Save the business rule, and generate the web app. Edit the rule in Visual Studio. You may need to press Refresh in the Solution Explorer toolbar of Visual Studio for the rule to appear.

Refresh button on the Solution Explorer may need to be pressed in order for the rule to appear.

Replace the code base with the following.

C#:

using System;
using System.Web.Security;
using MyCompany.Data;
using MyCompany.Security;

namespace MyCompany.Rules
{
    public partial class UsersBusinessRules : MyCompany.Data.BusinessRules
    {

        /// <summary>
        /// This method will execute in any view before an action
        /// with a command name that matches "Update".
        /// </summary>
        [Rule("r102")]
        public void r102Implementation(
                    FieldValue userID,
                    string userName,
                    FieldValue password,
                    FieldValue email,
                    FieldValue comment,
                    FieldValue passwordQuestion,
                    FieldValue passwordAnswer,
                    FieldValue isApproved,
                    DateTime? lastActivityDate,
                    DateTime? lastLoginDate,
                    DateTime? lastPasswordChangedDate,
                    DateTime? creationDate,
                    FieldValue isLockedOut,
                    DateTime? lastLockedOutDate,
                    int? failedPasswordAttemptCount,
                    DateTime? failedPasswordAttemptWindowStart,
                    int? failedPasswordAnswerAttemptCount,
                    DateTime? failedPasswordAnswerAttemptWindowStart,
                    FieldValue roles)
        {
            // prevent execution of CRUD operations by the application framework
            PreventDefault();
            // get user object by name
            MembershipUser user = Membership.GetUser(userName);
            if (user != null)
            {
                // update "Email" if changed
                if (email.Modified)
                {
                    user.Email = Convert.ToString(email.Value);
                    Membership.UpdateUser(user);
                }
                // update "Is Approved" if changed
                if (isApproved.Modified)
                {
                    user.IsApproved = Convert.ToBoolean(isApproved.Value);
                    Membership.UpdateUser(user);
                }
                // unlock user account if necessary
                if (isLockedOut.Modified)
                {
                    if (Convert.ToBoolean(isLockedOut.Value))
                    {
                        Result.Focus("IsLockedOut", Localize("UserCannotBeLockedOut",
                            "User cannot be locked out. If you want to prevent this " +
                            "user from being able to login then simply mark user as" +
                            " \'Not Approved\'."));
                        throw new Exception(Localize("ErrorSavingUser",
                            "Error saving user account."));
                    }
                    user.UnlockUser();
                }
                // update "Comment" if changed
                if (comment.Modified)
                {
                    user.Comment = Convert.ToString(comment.Value);
                    Membership.UpdateUser(user);
                }
                // update "Roles" if changed
                if (roles.Modified)
                {
                    string[] newRoles = Convert.ToString(roles.Value).Split(',');
                    string[] oldRoles = System.Web.Security.Roles.GetRolesForUser(
                        user.UserName);
                    foreach (string role in oldRoles)
                        if (!(String.IsNullOrEmpty(role)) && (Array.IndexOf(
                            newRoles, role) == -1))
                            System.Web.Security.Roles.RemoveUserFromRole(
                                user.UserName, role);
                    foreach (string role in newRoles)
                        if (!(String.IsNullOrEmpty(role)) &&
                            (Array.IndexOf(oldRoles, role) == -1))
                            System.Web.Security.Roles.AddUserToRole(
                                user.UserName, role);
                }
            }
        }
    }
}

Visual Basic:

Imports MyCompany.Data
Imports System
Imports System.Web.Security

Namespace MyCompany.Rules

    Partial Public Class UsersBusinessRules
        Inherits MyCompany.Data.BusinessRules

        ''' <summary>
        ''' This method will execute in any view before an action
        ''' with a command name that matches "Update".
        ''' </summary>
        <Rule("r102")> _
        Public Sub r102Implementation( _
                    ByVal userID As FieldValue, _
                    ByVal userName As String, _
                    ByVal password As FieldValue, _
                    ByVal email As FieldValue, _
                    ByVal comment As FieldValue, _
                    ByVal passwordQuestion As FieldValue, _
                    ByVal passwordAnswer As FieldValue, _
                    ByVal isApproved As FieldValue, _
                    ByVal lastActivityDate As Nullable(Of DateTime), _
                    ByVal lastLoginDate As Nullable(Of DateTime), _
                    ByVal lastPasswordChangedDate As Nullable(Of DateTime), _
                    ByVal creationDate As Nullable(Of DateTime), _
                    ByVal isLockedOut As FieldValue, _
                    ByVal lastLockedOutDate As Nullable(Of DateTime), _
                    ByVal failedPasswordAttemptCount As Nullable(Of Integer), _
                    ByVal failedPasswordAttemptWindowStart As Nullable(Of DateTime), _
                    ByVal failedPasswordAnswerAttemptCount As Nullable(Of Integer), _
                    ByVal failedPasswordAnswerAttemptWindowStart As Nullable(Of DateTime), _
                    ByVal roles As FieldValue, _
                    ByVal confirmPassword As String, _
                    ByVal roleID As Nullable(Of Integer))
            ' prevent execution of CRUD operations by the application framework
            PreventDefault()
            ' get user object by name
            Dim user As MembershipUser = Membership.GetUser(userName)
            If Not (user Is Nothing) Then
                ' update "Email" if changed
                If email.Modified Then
                    user.Email = Convert.ToString(email.Value)
                    Membership.UpdateUser(user)
                End If
                ' update "Is Approved" if changed
                If isApproved.Modified Then
                    user.IsApproved = Convert.ToBoolean(isApproved.Value)
                    Membership.UpdateUser(user)
                End If
                ' unlock user account if necessary
                If isLockedOut.Modified Then
                    If (Convert.ToBoolean(isLockedOut.Value)) Then
                        Result.Focus("IsLockedOut", Localize("UserCannotBeLockedOut",
                            "User cannot be locked out. If you want to prevent this " +
                            "user from being able to login then simply mark user as " +
                            "'Not Approved'."))
                        Throw New Exception(Localize("ErrorSavingUser",
                                "Error saving user account."))
                    End If
                    user.UnlockUser()
                End If
                ' update "Comment" if changed
                If comment.Modified Then
                    user.Comment = Convert.ToString(comment.Value)
                    Membership.UpdateUser(user)
                End If
                ' update "Roles" if changed
                If roles.Modified Then
                    Dim newRoles() As String = Convert.ToString(roles.Value).Split(",")
                    Dim oldRoles() As String = System.Web.Security.Roles.GetRolesForUser(
                        user.UserName)
                    For Each role As String In oldRoles
                        If Not (String.IsNullOrEmpty(role) And (Array.IndexOf(
                                                                newRoles, role) = -1)) Then
                            System.Web.Security.Roles.RemoveUserFromRole(user.UserName, role)
                        End If
                    Next
                    For Each role As String In newRoles
                        If Not (String.IsNullOrEmpty(role) And (Array.IndexOf(
                                                                oldRoles, role) = -1)) Then
                            System.Web.Security.Roles.AddUserToRole(user.UserName, role)
                        End If
                    Next
                End If
            End If
        End Sub
    End Class
End Namespace

Save the file.

Delete

Create another business rule:

Property Value
Type C# / Visual Basic
Command Name Delete
Phase Before

Save, regenerate the web app, and open the business rule file in Visual Studio. Replace the code:

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;
using MyCompany.Security;

namespace MyCompany.Rules
{
    public partial class UsersBusinessRules : MyCompany.Data.BusinessRules
    {

        /// <summary>
        /// This method will execute in any view before an action
        /// with a command name that matches "Delete".
        /// </summary>
        [Rule("r103")]
        public void r103Implementation(
                    FieldValue userID,
                    string userName,
                    string password,
                    string email,
                    string comment,
                    string passwordQuestion,
                    string passwordAnswer,
                    bool? isApproved,
                    DateTime? lastActivityDate,
                    DateTime? lastLoginDate,
                    DateTime? lastPasswordChangedDate,
                    DateTime? creationDate,
                    bool? isLockedOut,
                    DateTime? lastLockedOutDate,
                    int? failedPasswordAttemptCount,
                    DateTime? failedPasswordAttemptWindowStart,
                    int? failedPasswordAnswerAttemptCount,
                    DateTime? failedPasswordAnswerAttemptWindowStart)
        {
            // prevent execution of CRUD operations by the application framework
            PreventDefault();
            // delete the user account
            MembershipUser user = Membership.GetUser(userName);
            Membership.DeleteUser(user.UserName);
            // instruct the client library to display the previous view
            Result.ShowLastView();
            // instruct the client library to show a confirmation message
            Result.ShowMessage(String.Format(Localize("UserHasBeenDeleted",
                "User \'{0}\' has been deleted."), user.UserName));
        }
    }
}

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 UsersBusinessRules
        Inherits MyCompany.Data.BusinessRules
        
        ''' <summary>
        ''' This method will execute in any view before an action
        ''' with a command name that matches "Delete".
        ''' </summary>
        <Rule("r103")> _
        Public Sub r103Implementation( _
                    ByVal userID As FieldValue, _
                    ByVal userName As String, _
                    ByVal password As String, _
                    ByVal email As String, _
                    ByVal comment As String, _
                    ByVal passwordQuestion As String, _
                    ByVal passwordAnswer As String, _
                    ByVal isApproved As Nullable(Of Boolean), _
                    ByVal lastActivityDate As Nullable(Of DateTime), _
                    ByVal lastLoginDate As Nullable(Of DateTime), _
                    ByVal lastPasswordChangedDate As Nullable(Of DateTime), _
                    ByVal creationDate As Nullable(Of DateTime), _
                    ByVal isLockedOut As Nullable(Of Boolean), _
                    ByVal lastLockedOutDate As Nullable(Of DateTime), _
                    ByVal failedPasswordAttemptCount As Nullable(Of Integer), _
                    ByVal failedPasswordAttemptWindowStart As Nullable(Of DateTime), _
                    ByVal failedPasswordAnswerAttemptCount As Nullable(Of Integer), _
                    ByVal failedPasswordAnswerAttemptWindowStart As Nullable(Of DateTime), _
                    ByVal roles As String, _
                    ByVal confirmPassword As String, _
                    ByVal roleID As Nullable(Of Integer))
            ' prevent execution of CRUD operations by the application framework
            PreventDefault()
            ' delete the user account
            Dim user As MembershipUser = Membership.GetUser(userName)
            Membership.DeleteUser(user.UserName)
            ' instruct the client library to display the previous view
            Result.ShowLastView()
            ' instruct the client library to show a confirmation message
            Result.ShowMessage(String.Format(Localize("UserHasBeenDeleted",
                "User {0} has been deleted."), user.UserName))
        End Sub
    End Class
End Namespace

Save the code.

Monday, November 26, 2012PrintSubscribe
SQL Business Rules for Oracle Databases

SQL business rules are implemented in the programing language supported by application database engine.

If an Oracle database is the foundation of your data tier, then the programming language of SQL business rules is PL/SQL.

Consider Employees page displaying createForm1 in a project created straight from HR sample database.

Page 'Employees' displaying 'createForm1' view in a project created from the sample HR database available with Oracle database engines

None of the fields has a default value. Let’s assign default values to First Name, Last Name, Hire Date, and Salary.

Start Project Designer, activate Controllers tab, locate EMPLOYEES data controller and start creating a new SQL business rule.

Creating a new SQL business rule in Code On Time application generator

Configure the rule as follows:

Property Value
Command Name New
Type SQL
Phase Execute
Script

begin
    :FIRST_NAME := 'John';
    :LAST_NAME := 'Doe';
    :HIRE_DATE := sysdate;
    select avg(SALARY) into :SALARY from EMPLOYEES;
end;

Save the rule.

The script is written in PL/SQL. The highlighted field names are referenced as parameters in the script text.

image

When executed, the script will assign static values to First Name and Last Name fields.

The current system date will be assigned to Hire Date field.

An average of all employee salaries will be assigned to Salary field.

SQL business rule writtent in PL/SQL assigns default values to the field when a user starts creating a new record

The full power of PL/SQL is available to application developers when creating applications with Code On Time.

Saturday, November 10, 2012PrintSubscribe
RESTful Client-Side Validation

Data integrity can be ensured on different tiers of a web application. Code On Time web apps take advantage of the business rules engine that allows creating JavaScript Business Rules (Client Tier), Code Business Rules (Application Tier), and SQL Business Rules (Data Tier).

About Business Rules

Business rules are abstracted from the presentation of data. Developers manipulate field values directly as if the field values are local variables. The client library and application framework pass collections of values to the business rules making unnecessary a complex task of inspecting user interface elements. A business rule can access “old” value, “new” value, and “current” value of any field. It is also known if a field is “read-only” or “modified”. Business rules are executed in response to actions that have “before”, “execute”, and “after” phase. Changes to the values of the fields may affect the data that ends up in the database. Calculated field values are presented to the user on the client device.

This approach to business rule implementation allows continues improvement to the user interface client library.  It guarantees that business rules will remain unchanged even for the future supported client devices.

Selecting an Application Tier

The major challenge is to select an application tier for a business rule implementation.

The client tier is most commonly used to correct user spelling or for basic data integrity enforcement. For example, formatting of a phone number most definitely lends itself to a client side business rule. Client business rules allow avoiding a server-side round trip.

If a business rule requires a database lookup then the data tier works best in most situation. A script written in SQL dialect of the application database engine can select data from a table, call a stored procedure, and perform complex data manipulations.

Some business rules may require access to operating system resources, file system, or web services. Application tier business rules are written in C# or Visual Basic. The full power of Microsoft.NET is at disposal of a developer. “Code” business rules supersede SQL business rules at a cost of using special classes when a database access is required.

Hybrid Business Rules

If a server-side data is required for a client-side JavaScript business rule, then the business rule is a hybrid. This type of rules is difficult to implement.

The server-code implemented on the application or data tier cannot have a “conversation” with a user. Conditional execution with a user confirmation can be performed on the client only. The client business rule must have a way to request information from the server before confronting a user with requests for additional information.

RESTFul Application Server

Code On Time web applications may include application server components that enable interaction with clients supporting Representational State Transfer protocol know as REST. When enable, the application server components can respond to HTTP requests for information or commands to execute an action.

The  responses to such HTTP request are encoded in XML or JSON. The latter is a great match to JavaScript Business Rules since a response is essentially a JavaScript object.

Example of a RESTful Business Rule

Consider entering of new products in the Northwind sample.

Entering a new product in 'createForm1' in a web app created with Code OnTime application generator

There is product with the name “Chai” with a different price. The existing product is supplied by another vendor.

A list of products in 'Northwind' web app sample created with Code On Time

There may be a business requirement to warn a user about a potential duplicate.

A business rule written in JavaScript may contact the app to verify if a matching product exists. The URL of a web request may look as follow:

http://demo.codeontime.com/northwind/appservices/Products?ProductName=Chai

or

http://demo.codeontime.com/northwind/appservices/Products?ProductName_Filter_Equals=Chai

Here is the response encoded in XML.

<?xml version="1.0" encoding="utf-8"?>
<Products totalRowCount="1" pageSize="100" pageIndex="0" rowCount="1">
  <items>
    <item ProductName="Chai" SupplierID="1" CategoryID="1" QuantityPerUnit="10 boxes x 20 bags" 
          UnitPrice="$18.00" UnitsInStock="39" UnitsOnOrder="0" ReorderLevel="10" 
          Discontinued="False" ProductID="1" 
          SupplierCompanyName="Exotic Liquids" CategoryCategoryName="Beverages" />
  </items>
</Products>

The business rule can display a warning to a user about a potential duplicate. If a user does not confirm creation of a duplicate product, then a new record is not created.

First, may sure to enable REST requests to the data controller products. Select the data controller in Project Explorer and change it as follows.

Property Value
Representational State Transfer (REST) Configuration

Uri: .
Users: *

This will ensure that only authenticated users can send requests to application server components.

Enter a new JavaScript business rule in Products data controller configured as follows:

Property Value
Type JavaScript
Command Name Insert
Phase Before

Enter this code in the Script property of the rule and click OK button.

var duplicateProduct = null;
$.ajax({
    url: '../appservices/Products?ProductName=' + [ProductName],
    cache: false,
    async: false,
    dataType: 'json',
    success: function (result) {
        if (result.Products.length > 0)
            duplicateProduct = result.Products[0];
    }
});
if (duplicateProduct)
    if (confirm('This product is a duplicate. Continue?') == false) {
        this.preventDefault();
        this.result.focus('ProductName',
            'Product with this name and price of {0} is supplied by "{1}".',
            duplicateProduct.UnitPrice, duplicateProduct.SupplierCompanyName);
    }

This is how the rule will be displayed in Project Explorer.

A 'hybrid' validation business rule in Project Explorer

Click Browse and navigate to Products page. Enter a new product with the name “Chai” and click OK to save the new record.

A standard browser confirmation will be displayed.

JavaScript business rule dispalys a confirmation if a duplicate product is detected

Click Cancel button to prevent creation of the product. The focus will be on Product Name field. The information about the duplicate product will be displayed next to the field.

JavaScript business rule cancels 'Insert' action and displayes duplicate product info next to 'ProductName' field if a user clicks 'Cancel' button in confirmation window.

The script makes a web request to the application server to locate a potential duplicate product. The request is executed synchronously making both user and web browser wait for its completion.

The scripts analyzes the response and displays a confirmation if there is a duplicate product. The supplier name and unit price of the existing product are displayed next to the product name field. A call to the method preventDefault will not allow the Insert action to proceed.

The screenshot displays a JSON response to a request for a product by name as presented in Visual Studio 2012.

JSON response to a request for a product in Debug mode as presented by Visual Studio 2012