Blog: Posts from March, 2012

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Posts from March, 2012

Saturday, March 31, 2012Print Subscribe

Suppose that you want to change a field that renders as a textbox into a static drop down list of items, such as the Reorder Level field in the Products controller of the Northwind sample. By default, users can enter any numeric value in the field.

Let’s change this by offering a drop down list of predefined items, and have the item values displayed as words.

You can do this at design time, as explained in Creating Static Lookup Items. However, there may be other situations when you don’t want to change the physical properties of the application. For example, the static items maybe displayed only to users in specific roles. For this purpose, you can use virtualization node sets.

First, you will need to enable shared business rules.

Next, switch to the web application generator, select the project name, and press Develop. This will open the project in Visual Studio.

In the Solution Explorer, navigate to ~/App_Code/Rules/SharedBusinessRules.cs(vb). The code will need to enable virtualization if the controller name is “Products”. The virtualized Products controller will have a modified ReorderLevel field. The Items Style will be changed to “Drop Down List”, and it will have the following static items:

Value	Text
0	Zero
5	Five
10	Ten
15	Fifteen
20	Twenty
25	Twenty-five
30	Thirty

Place the code into your SharedBusinessRules.cs(vb) file:

C#:

using System;
using System.Data;
using System.Collections.Generic;
using System.Linq;
using MyCompany.Data;

namespace MyCompany.Rules
{
    public partial class SharedBusinessRules : MyCompany.Data.BusinessRules
    {
        public override bool SupportsVirtualization(string controllerName)
        {
            if (controllerName == "Products")
                return true;
            return false;
        }

        protected override void VirtualizeController(string controllerName)
        {
            if (controllerName == "Products")
            {
                NodeSet().SelectField("ReorderLevel")
                    .SetItemsStyle("DropDownList")
                    .CreateItem(0, "Zero")
                    .CreateItem(5, "Five")
                    .CreateItem(10, "Ten")
                    .CreateItem(15, "Fifteen")
                    .CreateItem(20, "Twenty")
                    .CreateItem(25, "Twenty-five")
                    .CreateItem(30, "Thirty");
            }
        }
    }
}

Visual Basic:

Imports MyCompany.Data
Imports System
Imports System.Collections.Generic
Imports System.Data
Imports System.Linq

Namespace MyCompany.Rules

    Partial Public Class SharedBusinessRules
        Inherits MyCompany.Data.BusinessRules

        Public Overrides Function SupportsVirtualization(controllerName As String) As Boolean
            If (controllerName = "Products") Then
                Return True
            Else  
                Return False
            End If
        End Function

        Protected Overrides Sub VirtualizeController(controllerName As String)
            If (controllerName = "Products") Then
                NodeSet().SelectField("ReorderLevel") _
                    .SetItemsStyle("DropDownList") _
                    .CreateItem(0, "Zero") _
                    .CreateItem(5, "Five") _
                    .CreateItem(10, "Ten") _
                    .CreateItem(15, "Fifteen") _
                    .CreateItem(20, "Twenty") _
                    .CreateItem(25, "Twenty-five") _
                    .CreateItem(30, "Thirty")
            End If
        End Sub
    End Class
End Namespace

Save this file and run the web application. You will see that the Products controller now displays Reorder Level filter options as words, and the field is rendered as a drop down list.

Labels: Database Lookups, Web Application Generator, Workflow

Saturday, March 31, 2012Print Subscribe

Creating Static Lookup Items

In the Products table of Northwind sample database, there is a Reorder Level field. It is rendered as a textbox where users can type in any number to trigger the product reorder. If you look at the available filtering options of the Reorder Level field, you can see that there is a limited number of values stored in the database (0, 5, 10, 15, 20, 25, and 30).

Let’s change this field into a static dropdown list, and have the values displayed as words instead of numbers. For example, “0” will be Zero, “5” will be Five, and so on.

Open the web application generator, select the project name, and select Design. Switch to the Controllers tab in the Project Explorer, and double-click on Products / Fields / Reorder Level node. Change Items Style of Reorder Level field to “Drop Down List”, and press OK to save the field.

Scroll to the top of the Designer, and click on the Items tab. On the action bar, select New | New Item.

Each item represents an option available in the dropdown list. The Value is stored in the database, while the Text is displayed to the user.

Enter the following values:

Value	Text
0	Zero

Press OK to save the item. Using the same method, create more items with the following values:

Value	Text
5	Five
10	Ten
15	Fifteen
20	Twenty
25	Twenty-five
30	Thirty

In the top left corner, press Generate to generate the web app. A Preview window will open. Navigate to Products page, and you will see that the Reorder Level is now displayed with words. Edit a record, and the Reorder Level is now a static dropdown lookup.

The adaptive filter in the Reorder Level column also reflects the static values.

On the action bar, select Report | PDF Document. You will see that Reorder Level displays the Text, and not the Value of the field.

Labels: Database Lookups, User Interface, Web Application Generator

Saturday, March 31, 2012Print Subscribe

“Soft” Filtering With Business Rules

Code On Time web applications offer impressive adaptive filtering and search capabilities that require zero programming. Consider the following screen shot from the Northwind sample.

Application user has selected specific categories,

specific suppliers,

a range of prices,

and specific values of product units on order.

A user can remove the filter at will by either clicking on individual filter elements or dismissing the entire filter.

An application developer can also configure a filter based on arbitrary conditions at runtime. The filter can be constructed just before the data is retrieved from the database. Users will see the filter as if they have selected all options on their own. End users can always cancel or adjust the “soft” filter to reveal more data rows.

This may be useful when a specific data row has to be brought to the application user’s attention. “Soft” filtering will work even better when combined with the auto highlight first row or auto select first row features.

Enable shared business rules in your web application and enter the following code.

C#:

using System;
using System.Data;
using System.Collections.Generic;
using System.Linq;
using MyCompany.Data;

namespace MyCompany.Rules
{
    public partial class SharedBusinessRules : MyCompany.Data.BusinessRules
    {
        [ControllerAction("Orders", "grid1", "Select", ActionPhase.Before)]
        public void AssignOrdersFilter()
        {
            if (!IsTagged("Filtered"))
            {
                AddTag("Filtered");
                DateTime startDate = new DateTime(1998, 1, 1, 0, 0, 0, DateTimeKind.Utc);
                DateTime endDate = new DateTime(1998, 6, 1, 23, 59, 59, DateTimeKind.Utc);
                AssignFilter(
                    new FilterValue("OrderDate",
                        RowFilterOperation.Between, startDate, endDate),
                    new FilterValue("EmployeeLastName",
                        RowFilterOperation.Equal, "Callahan"),
                    new FilterValue("ShipViaCompanyName",
                        RowFilterOperation.Includes, "Speedy Express", "United Package"),
                    new FilterValue("Freight", 
                        RowFilterOperation.Between, 10, 30)
                );
                Result.ShowViewMessage("A \"soft\" filter has been applied to this list.");
            }
        }
    }
}

Visual Basic:

Imports MyCompany.Data
Imports System
Imports System.Collections.Generic
Imports System.Data
Imports System.Linq

Namespace MyCompany.Rules
    Partial Public Class SharedBusinessRules
        Inherits MyCompany.Data.BusinessRules

        <ControllerAction("Orders", "grid1", "Select", ActionPhase.Before)> _
        Public Sub AssignOrdersFilter()
            If Not IsTagged("Filtered") Then
                AddTag("Filtered")
                Dim startDate As DateTime = New DateTime(1998, 1, 1, 0, 0, 0, DateTimeKind.Utc)
                Dim endDate As DateTime = New DateTime(1998, 6, 1, 23, 59, 59, 
                    DateTimeKind.Utc)
                AssignFilter(
                    New FilterValue("OrderDate",
                        RowFilterOperation.Between, startDate, endDate),
                    New FilterValue("EmployeeLastName",
                        RowFilterOperation.Equal, "Callahan"),
                    New FilterValue("ShipViaCompanyName",
                        RowFilterOperation.Includes, "Speedy Express", "United Package"),
                    New FilterValue("Freight",
                        RowFilterOperation.Between, 10, 30)
                )
                Result.ShowViewMessage("A ""soft"" filter has been applied to this list.")
            End If
        End Sub
    End Class
End Namespace

Save the code file and navigate to the page Orders. The method AssignOrdersFilter will be invoked when the data is about to be retrieved. The method will apply a filter one time only in the lifecycle of the page instance displayed in the web browser to prevent interference with application user actions.

Notice that we are filtering by UTC dates to ensure that Microsoft.NET will not try to compensate for the time difference between the server and the web browser.

In the end, the method will display a view-level message rendered just above the grid view informing the app user about the “soft”- filter.

Select data view Customers/ Orders / container1 / view in the Project Explorer.

If you enable Search On Start in the data view properties then the Orders page will open up with the search bar pre-filled with filter values and no data will be displayed. Users will have to click Search to initiate the retrieval of data.

If you have enabled automatic selection or highlighting of the first row in the properties of the page data view then the view will perform the first action in the context menu of the first data row or simulate a click in the first row. This sort of behavior will happen even if you do not “soft” filter the data.

You can also coincide the selection or highlighting of the first row with the assignment of a “soft” filter in business rules by calling Result.SelectFirstRow or Result.HightlightFirstRow right after the call of ShowViewMessage method.

For example, this is the effect of Result.HighlightFirstRow method call.

Developers should use access control rules or filter expressions when the application business logic does not permit cancellation of data filters at will by the application users.

Labels: Business Rules/Logic, Web Application Generator