Blog: Posts from June, 2012

Blog

Posts from June, 2012

Wednesday, June 27, 2012Print Subscribe

Converting Field Values with C# and Visual Basic

The CustomerID field from the Customers controller should have all values formatted in uppercase.

Let’s create a business rule in C# or Visual Basic to convert all user input to uppercase.

Start the Project Designer. In the Project Explorer, switch to the Controllers tab and double-click on Customers controller node.

Change the Handler property:

Property	New Value
Handler	CustomersRule

Press OK to save the controller. 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

Exit the designer and generate the application.

Click on the project name, and press Design. Visual Studio will open the project.

In the Solution Explorer, double-click on ~\App_Code\Rules\CustomersRule.cs(vb) file.

Replace the sample code base with the following:

C#:

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

namespace MyCompany.Rules
{
    public partial class CustomersRule : MyCompany.Data.BusinessRules
    {
        [ControllerAction("Customers", "Insert", ActionPhase.Before)]
        [ControllerAction("Customers", "Update", ActionPhase.Before)]
        [ControllerAction("Customers", "Calculate", ActionPhase.Execute)]
        public void CalculateCustomerID(string customerID)
        {
            UpdateFieldValue("CustomerID", customerID.ToUpper());
        }
    }
}

Visual Basic:

Imports MyCompany.Data
Imports System
Imports System.Collections.Generic
Imports System.Data
Imports System.Linq
Namespace MyCompany.Rules
    Partial Public Class CustomersRule
        Inherits MyCompany.Data.BusinessRules
        <ControllerAction("Customers", "Insert", ActionPhase.Before)>
        <ControllerAction("Customers", "Update", ActionPhase.Before)>
        <ControllerAction("Customers", "Calculate", ActionPhase.Execute)>
        Public Sub CalculateCustomerID(ByVal customerID As String)
            UpdateFieldValue("CustomerID", customerID.ToUpper())
        End Sub
    End Class
End Namespace

Save the file, and switch to the web application. Navigate to the Customers page, and create a new record. Type in lowercase letters for Customer# field.

Press Tab or click on another area of the page. The text in Customer# will be converted to uppercase.

The same business logic can be implemented with the help of SQL Business Rules.

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

Wednesday, June 27, 2012Print Subscribe

Browsing Project Configuration Elements

The picture shows the Project Designer window of a Northwind web application.

The screen is split into two parts.

The flexible left side of the window holds the Project Configuration Browser. This window initially displays a list of pages, with other tabs that display Controllers, User Controls, All Commands, All Fields, All Views, and All Data Fields.

The resizable right side holds the Project Explorer. It displays a logical hierarchy of the application configuration elements.

The options on the Project Browser toolbar allows the developer to generate the app, develop in Visual Studio, open the folder, or exit the Project Designer.

The Generate button will generate and open the application in the Preview window. The Browse button will generate and open the application in the default web browser. The generated application is stored locally and executed by IIS Express.

The Develop button will open the solution in Visual Studio. If it is already open, the button will switch to Visual Studio.

The Exit button will close the Designer and return to the project settings.

The Project Browser displays lists of project configuration elements. The lists offer the same Quick Find, sorting, and filtering capabilities that are available in Code On Time web applications. Notice that the Project Browser runs locally and only displays the project configuration stored on the hard drive without interacting with any web server.

Clicking on a link in the first column will navigate to the properties form of the selected item.

There may be additional tabs at the top of the window that allow access to related project configuration elements. The next screenshot shows Containers, Data Views, and Controls associated with Customers page.

The context menu Sync command selects the relevant element in the Project Explorer window on the right side of the Designer.

Clicking on links in the breadcrumbs will navigate directly to the parent project configuration element. The Home link will lead to the Home page of the Project Configuration Browser. Pressing OK or Cancel on the main tab will navigate back up one level.

The Project Explorer, on the right side of the Designer, displays a full hierarchy of project configuration elements across three tabs: Pages, Controllers, and User Controls.

The toolbar at the top of the Project Explorer offers context-sensitive commands. The buttons Sync, Navigate To, and Home are always displayed.

The first button, Sync, will synchronize the Project Explorer hierarchy node with the project configuration element selected in the Project Browser window.

The second button, Navigate To, opens a search window that will help find a project configuration element by name or property value.

The third button will display a list of top-level items in the Project Browser. The list depends on the active tab in the Project Explorer. For example, if the button is pressed when Controllers tab is active, a list of controllers will be displayed in the Project Browser window.

The fourth button will allow creating a new data controller, user control, or top-level page.

Additional options may be displayed depending on the selected node.

Double-clicking on a node will open the properties form for that project configuration element in the Designer window.

If you select a project configuration element in Project Explorer and click OK button to save the changes, then the same element will remain selected in the form. If you Cancel changes, then the original properties will be displayed in the form.

Multiple elements of the same type can be selected in the hierarchy. Many elements in the Project Explorer have Cut, Copy, and Paste commands available in the context menu. Users can drag and drop project configuration elements to modify the project configuration hierarchy. Drag and drop commands will work on multiple nodes.

Labels: Designer, Web Application Generator

Monday, June 25, 2012Print Subscribe

SQL Upsert

Upsert is an insert operation with detection of duplicates. The application will update the existing record when a duplicate is detected instead of creating a new record instance. Modern database engines support a dedicated SQL command Merge that performs this function. Applications created with Code On Time offer an elegant mechanism of SQL Business Rules that allows creating flexible and configurable Merge operations.

Let’s implement upsert for the Products table of the Northwind sample. The picture below shows two duplicate records of the product “Chai”.

The upsert implementation will detect an attempt to insert a duplicated product, and will update the values of the existing one.

Delete the duplicate “Chai” record from the list of Products, and paste the following query into SQL Server Management Studio:

-- debug
declare @ProductID int
declare @ProductName nvarchar(40) = 'Chai'
declare @SupplierID int
declare @CategoryID int
declare @QuantityPerUnit nvarchar(20)
declare @UnitPrice money = 42
declare @UnitsInStock smallint
declare @UnitsOnOrder smallint
declare @ReorderLevel smallint
declare @Discontinued bit
declare @BusinessRules_PreventDefault int
-- end debug

select @ProductID = ProductID
from Products
where ProductName = @ProductName

if @ProductID is not null
begin 
    set @BusinessRules_PreventDefault = 1
    update Products
    set 
        SupplierID = IsNull(@SupplierID,SupplierID),
        CategoryID = IsNull(@CategoryID,CategoryID),
        QuantityPerUnit = IsNull(@QuantityPerUnit,QuantityPerUnit),
        UnitPrice = IsNull(@UnitPrice,UnitPrice),
        UnitsInStock = IsNull(@UnitsInStock,UnitsInStock),
        UnitsOnOrder = IsNull(@UnitsOnOrder,UnitsOnOrder),
        ReorderLevel = IsNull(@ReorderLevel,ReorderLevel),
        Discontinued = IsNull(@Discontinued,Discontinued)
    where ProductID = @ProductID
end

The sample debug parameters represent values of a new product where Product Name is “Chai”, and Unit Price is “42”. The script will try to find an existing product that matches the Product Name. If a match is found, then the application framework is instructed to prevent executing the default Insert command. This is accomplished by setting the value of @BusinessRules_PreventDefault parameter to true. Then the new record values will be used to update the existing product. If a new column value is null, then the current column value is preserved with the help of IsNull function.

Execute the query. A message will state that 1 row was affected. Go back to the application and refresh the view, and you will see that the query has only updated the existing “Chai” record.

Let’s integrate this script in a new business rule of Products controller.

Start the Project Designer. In the Project Explorer, switch to the Controllers tab. Right-click on Products / Business Rules node, and select New Business Rule option.

Use the following properties.

Property	Value
Command Name	Insert
Type	SQL
Phase	Before
Script	Copy and paste the script from above.

This business rule will execute before every Insert command.

The application framework will ignore the debug section. You can keep the debug section in the script or take it out – it will not make any difference.

Press OK to save the new business rule. On the toolbar, click Browse option.

Navigate to the Products page. Create a new product with the following field values:

Field	Value
Product Name	Chang
Category Name	Condiments
Unit Price	99

Instead of creating the new record, the application updated the existing product. It is automatically selected in the user interface.

This business rule will also work with the Import action. Create a spreadsheet, and paste in the following table:

Product Name	Supplier Company Name	Unit Price
Alice Mutton		120
Aniseed Syrup	Tokyo Traders	44
ABCDE		42

Save the spreadsheet as a CSV (Comma delimited) file type.

On the action bar of the web application, select Actions | Import from File option.

Make sure that the columns are matching, and press Import.

Confirm the operation. Sort by the Product Name field by clicking on the header text. Two of the records already existed, and Unit Price and Supplier Company Name for these records has been updated. The “ABCDE” Product Name was unique, so the row was added.

There are advantages of using SQL Business Rules over the standard Merge operation. If additional processing is required or duplicate records have to be staged in a separate table, then business rules provide more flexibility over the insert/update combination offered by Merge.

Labels: Business Rules/Logic, Web Application Generator