Business Rules/Logic

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Business Rules/Logic
Saturday, September 29, 2012PrintSubscribe
“Select” Action

The application framework initiates a Select action when a data view needs to load data from the server.

Let’s create an example using a Northwind sample web app to see when the Select action is fired in the server code.

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

New Business Rule context menu option in the Project Explorer.

Give this rule the following properties:

Property Value
Type SQL
Command Name Select
Phase Before
Script
set @Result_ShowAlert = 'Before'

Press OK to save the business rule. Right-click Orders / Business Rules and press New Business Rule again.

New Business Rule context menu option in the Project Explorer.

Assign these properties:

Property Value
Type SQL
Command Name Select
Phase Execute
Script
set @Result_ShowAlert = @CustomerCompanyName

Press OK to save. Create one more business rule with this configuration:

Property Value
Type SQL
Command Name Select
Phase After
Script
set @Result_ShowAlert = 'After'

Press OK to save. The Business Rules node should look like the picture below.

image

Assigning a value to @Result_ShowAlert creates a JavaScript expression that is added to the server response. As a page of data is rendered, the “alert” expressions will be consequently appended to the ClientScript property of the Result.

The client library will evaluate the entire ClientScript property content using eval function of JavaScript language. This will result in the sequence of alerts displayed to the user.

On the toolbar, press Browse.

Navigate to the Orders page. The first popup for Before phase will appear.

Alert showing 'Before' appears before the select command occurs.

Press OK, and alert for Execute phase will appear, showing the Customer Company Name of the first record.

Alert displaying the Customer Company Name of the data being selected.

Keep pressing OK, as each alert will display the Customer Company Name of each record displayed in the grid. After alerts for each selected data row have been displayed, the After phase popup will appear.

Alert displaying 'After' when the select command has been completed.

Click on a Customer Company Name link. The three alerts will appear in succession as well.

Alert displaying 'Before' when user navigates to the form view of an order.

When you press Edit in the form, no alerts will be shown – this is because Edit command only renders the form on the client without making a round trip to the server. The data has already been retrieved from the server when select command was fired.

No alert is displayed when the form enters edit mode - Edit command does not travel to the server.

Saturday, September 29, 2012PrintSubscribe
Passing Values to Custom Report Action

Many action require additional information that must be requested from the user. The Implementing a Custom Action tutorial in Getting Started series shows an example of such action.

The built-in Report action allows implementing custom report output created on the server. Developers can use external software or write code to produce the output.

Let’s consider requesting custom parameters and processing them when producing the output. The example assumes that there is an external URL that can accept ReportHeader. The action handler will redirect user to that URL.

The action handler will obtain several parameters from the following sources

  1. Confirmation data controller
  2. Selected row of the data view
  3. URL in the address bar of the browser

Confirmation Controller Configuration

Make sure that Reporting is enabled for your Northwind sample project.

Start the Project Designer. In the Project Explorer, switch to the Controllers tab and press New Controller icon on the toolbar.

New Controller context menu option in the Project Explorer.

Assign a name to the controller.

Property Value
Name ReportProperties

Press OK to save the controller. Right-click on ReportProperties / Fields node, and press New Field.

New Field context menu option for Fields node of ReportProperties confirmation controller.

Give this field the following settings.

Property Value
Name ReportHeader
Type String
Length 40
Allow null values True
Label Report Header

Press OK to save the field.

Adding Custom Report Action

Right-click on Orders / Actions / ag3 – New action group node, and press New Action.

New Action context menu option on an action group for Orders controller.

Give this action the following settings.

Property Value
Command Name Report
Command Argument _blank
Confirmation _controller=ReportProperties
_title=Configure properties for the report.
_width=500

Press OK to save the action.

Handling the Action

Create a controller business rule to handle the report action.

Right-click on Orders / Business Rules node.

New Business Rule context menu option in the Project Explorer.

Assign the following properties.

Property Value
Type C# / Visual Basic
Command Name Report
Command Argument _blank
Phase Execute

Press OK to save. On the toolbar, press Generate to create the business rule file.

When finished, right-click on Orders / Business Rules / Report, _blank (Code / Execute) - r100 controller node, and press Edit Rule in Visual Studio.

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

Visual Studio will load the project and display the source code file of the business rule. Replace the code with the following:

C#:

using System;
using MyCompany.Data;

namespace MyCompany.Rules
{
    public partial class OrdersBusinessRules : MyCompany.Data.BusinessRules
    {
        
        /// <summary>
        /// This method will execute in any view for an action
        /// with a command name that matches "Report" and argument that matches "_blank".
        /// </summary>
        [Rule("r100")]
        public void r100Implementation(
                    int? orderID, 
                    string customerID, 
                    string customerCompanyName, 
                    int? employeeID, 
                    string employeeLastName, 
                    DateTime? orderDate, 
                    DateTime? requiredDate, 
                    DateTime? shippedDate, 
                    int? shipVia, 
                    string shipViaCompanyName, 
                    decimal? freight, 
                    string shipName, 
                    string shipAddress, 
                    string shipCity, 
                    string shipRegion, 
                    string shipPostalCode, 
                    string shipCountry,
                    // custom arguments
                    string parameters_ReportHeader, // comes from confirmation
                    string xyz                      // comes from URL
                    )
        {
            // This is the placeholder for method implementation.
            Result.NavigateUrl =
                String.Format("~/Pages/OrdersReport.aspx?ReportHeader={0}&OrderID={1}&xyz={2}",
                    parameters_ReportHeader, orderID, xyz);

        }
    }
}

Visual Basic:

Imports MyCompany.Data
Imports System

Namespace MyCompany.Rules

    Partial Public Class OrdersBusinessRules
        Inherits MyCompany.Data.BusinessRules

        ''' <summary>
        ''' This method will execute in any view for an action
        ''' with a command name that matches "Report" and argument that matches "_blank".
        ''' </summary>
        <Rule("r100")>
        Public Sub r100Implementation( _
                    ByVal orderID As Nullable(Of Integer),
                    ByVal customerID As String,
                    ByVal customerCompanyName As String,
                    ByVal employeeID As Nullable(Of Integer),
                    ByVal employeeLastName As String,
                    ByVal orderDate As Nullable(Of DateTime),
                    ByVal requiredDate As Nullable(Of DateTime),
                    ByVal shippedDate As Nullable(Of DateTime),
                    ByVal shipVia As Nullable(Of Integer),
                    ByVal shipViaCompanyName As String,
                    ByVal freight As Nullable(Of Decimal),
                    ByVal shipName As String,
                    ByVal shipAddress As String,
                    ByVal shipCity As String,
                    ByVal shipRegion As String,
                    ByVal shipPostalCode As String,
                    ByVal shipCountry As String,
                    ByVal parameters_ReportHeader As String,
                    ByVal xyz As String
                    )
            'This is the placeholder for method implementation.            
            Result.NavigateUrl =
            String.Format("~/Pages/OrdersReport.aspx?ReportHeader={0}&orderId={1}&xyz={2}",
                          parameters_ReportHeader, orderID, xyz)

        End Sub
    End Class
End Namespace

Save the file.

Testing the Report Action

Switch back to the Project Designer. On the toolbar, press Browse.

Navigate to the Orders page. Append the URL parameter “?xyz=Value” to the current page.

Entering an 'xyz' URL parameter into the URL bar of the browser.

Press Enter to navigate to the URL. On the list of orders, highlight an order and activate the Report action on the action bar.

A row selected in the list of Orders. The Report action on the action bar is highlighted.

The confirmation controller will open. Enter a Report Header and press OK.

Confirmation controller with Report Header populated with the value 'Header1'.

The next page will display a server error – no page was created to handle the request. However, if you look at the URL, you will see that the values of fields specified in the business rule have been passed.

Values from the confirmation controller, data view, and previous URL parameters have been passed.

The values available for passing include already present URL parameters (xyz), a field value from the selected row (orderId), and the value specified by the user in a confirmation controller (reportHeader).

If no row was selected, the value from the first row in the grid will be passed.

If you do have a real application behind the URL, then one can expect the correct output to be produced.

Saturday, September 29, 2012PrintSubscribe
Extending Web Apps with REST and jQuery

Code On Time creates web apps with sophisticated pages composed of data views that allow searching, filtering, sorting, and browsing large data sets. The data views are driven by data controllers constructed by application generator for each database table and view included in a project. Developers customize their apps by changing properties of data controller configuration elements.

One can think of application data controllers as blocks of a LEGO kit that are custom-maid for a database project. Sometimes the built-in functionality of a data controller may not meet your presentation requirements. You want to build a LEGO model of a medieval castle  but the rooftops don’t look the right way!

This is where the REST APIs of data controllers come handy. Developers can create a custom presentation with jQuery or any other popular JavaScript client library while taking advantage of a REST-enabled application server built in a generated web app.

Application pages can be extended with custom user controls hosting any HTML content and server-side ASP.NET components. Let’s implement a custom user control that will provide an alternative method of browsing the product catalog in Northwind sample.

Enabling REST for “Products” Data Controller

Begin with enabling REST for the data controller Products. Programmatic access to data controllers via REST is disabled by default. A developer can configure a data controller in Designer to allow REST. Developers can also write code to allow REST for data controllers based on arbitrary conditions.

Start Project Designer, select Products node on the Controllers tab of Project Explorer.

Activating properties of a data controller in Project Designer of Code On Time web application generator

Configure the data controller:

Property Value
Representational State Transfer (REST) Configuration Uri: .
Users: *

Click OK button to save the changes.

The built-in application server will allow access to any URI that targets the Products data controller if a user is authenticated. The “URI” parameter is a regular expression that matches any URI as defined. The “Users” parameter allows only authenticated users to access Products data controller via the application server.

For example, the following URI of MyProducts data controller will require a valid application user name and password to return a list of products sorted in descending order of UnitPrice. Click on the link and enter admin/admin123% or user/user123% when a login prompt is displayed.

http://demo.codeontime.com/northwind/appservices/MyProducts?_sortExpression=UnitPrice%20desc

Creating a User Control

Activate Pages tab of Project Explorer and choose “New Page” option on the toolbar.

Creating a new page in Project Designer of Code On Time web application generator

Enter the following properties and click OK to save the page.

Property Value
Name DemoPage
Index 1005
Roles ?

The page is configured to be accessible to all users including those visiting the site anonymously.

Select User Controls tab at the bottom of Project Explorer and choose New User Control button on the toolbar.

Creating a new user control in a Code On Time web application

Enter “ProductBrowserControl” in the name and save. Right-click the new user control node in Project Explorer and select Copy.

Copying a user control to Clipboard in Code On Time Project Designer

Activate Pages tab of Project Explorer, right-click Demo Page node and choose Paste.

Adding an existing custom user control to a page in web app created with Code On Time application generator

Click Browse button on the Project Designer toolbar. The application generator will produce the user control files and launch a default web browser. Switch back to the generator window.

Right-click the Demo Page / c101/ control1 – ProductBrowserControl node and choose Edit in Visual Studio option.

Activating Visual Studio to modify the markup of a user control instance placed in a page container

The definition of the user control will be displayed in Visual Studio. If you do not have Visual Studio installed, then open the file ~/Controls/ProductBrowserControl.ascx in Notepad.


Implementing Product Catalog Browser with jQuery and REST

Replace the markup of the user control with the following definition and save the file.

<%@ Control Language="C#" AutoEventWireup="true" %>
<!-- this tag is needed to enable jQuery IntelliSense only -->
<script src="../Scripts/_System.js" type="text/javascript"></script>
<!-- the user interface of the control -->
<input id="Query" type="text" />
<button id="FindButton">
    Find</button>
<div id="ProductListPanel">
    <select id="ProductList" size="15">
    </select>
</div>
<!-- the implementation of the product catalog -->
<script type="text/javascript">
    $(document).ready(function () {
        $('#ProductListPanel').hide();
        setTimeout(function () {
            $('#Query').focus();
        }, 10);
        $('#FindButton').click(function (e) {
            e.preventDefault();
            var query = '?_sortExpression=ProductName&_q=' +
                    encodeURIComponent($('#Query').val());
            $.ajax({
                url: '../appservices/Products' + query,
                cache: false,
                dataType: 'json',
                success: function (data) {
                    $('#ProductList option').remove();
                    $.each(data.Products, function (index, product) {
                        $('<option>')
                                .text(
                                    product.ProductName + ' / ' +
                                    product.CategoryCategoryName + ' / ' +
                                    product.SupplierCompanyName + ' / ' +
                                    product.UnitPrice)
                                .attr('value', product.ProductID)
                                .appendTo($('#ProductList'));
                    });
                    $('#ProductListPanel').show();
                }
            });
        });
    });
</script>

The first script tag in the user control is optional. It is provided only to enable IntelliSense for jQuery in Visual Studio.

Element ProductList will be populated with the matching products when a user initiates a search operation.

The second script tag defines a script that will execute as soon as a page with the user control has been loaded in a web browser. The script registers an event handler attached to a button. The handler will create an AJAX request to the highlighted application URL. Also note the highlighted data type “json” in the ajax method arguments. Successful response will have matching products displayed in the list box by success method.

Right-click the Demo Page node on the Pages tab of Project Explorer and choose View in Browser option in the context menu.

Browsing a specific page in a project created with Code On Time web application generator

The page will be displayed in a default web browser window. The identity of a user is not know. The login link is displayed in the right top corner of the membership bar.

An instance of 'ProductCatalogBrowser' control displayed on a page in a web browser displayed to an anonymous user

If a user clicks on Find button then a standard browser window requesting user credentials will be displayed. The application server has found out that a user must be authenticated to initiate execution of a service request involving Products data controller. That explains the browser login prompt.

A standard browser login window displayed when a data controller REST resource requires authentication

If a user enters a valid user and password (for example  admin/admin123% or user/user123% ), then a list of matching products is displayed. Note that the user is still not authenticated to access the pages of the web app.

Product Catalog Browser displays a list of products to a user with a known identity

If a user click on the “Login” link of the membership bar and successfully signs in, then an attempt to search for products will not cause additional requests for authentication. The application server detects the user identity and allows access to the requested URI.

Authenticated web app user can interact with custom controls that take advantage of REST APIs of the built-in application server without the need to login