Code On Time: Business Rules/Logic

Monday, June 4, 2012Print Subscribe

Some applications require protected input of sensitive field values. Examples include a user password, social security number, or national id.

Let’s configure a Social Security Number field on the Employees table. Start SQL Server Management Studio. In the Object Explorer, right-click on Databases / Northwind / Tables / dbo.Employees node. Select Design option.

Add the following column:

Column Name	Data Type	Allow Nulls
SocialSecurityNumber	nvarchar(50)	True

Save your changes and refresh the Employees data controller.

Generate the project. Navigate to the Employees page and edit a record. Change the Social Security Number field value and save. The field value is visible and unprotected.

Start the Project Designer. In the Project Explorer, double-click on Employees / container1 / view1 / editForm1 / c1 – Employees / SocialSecurityNumber data field node.

Change the properties of the data field:

Property	New Value
Columns	10
Text Mode	Password

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

When the web app opens in the browser, navigate to Employees and select a record. The field value will be presented to the user as a series of asterisks (*).

Edit the record. The field value will be displayed as dots, and cannot be copied or otherwise extracted.

This solution is effective in preserving the confidentiality of the information.

A common practice is to reveal a part of the protected information. It may be necessary to reveal the last four digits of the Social Security Number.

Switch back to the Project Designer. In the Project Explorer, switch to the Controllers tab. Right-click on Employees / Fields node and select New Field.

Configure the field using the following values:

Property	Value
Name	SocialSecurity4Digit
Type	String
Length	50
Allow null values.	True
The value of this field is computed at run-time by SQL expression	True
SQL Formula	'*--' + SUBSTRING(Employees.SocialSecurityNumber, (LEN(Employees.SocialSecurityNumber)-3), LEN(Employees.SocialSecurityNumber))
Label	Social Security Number
Values of this field cannot be edited	True

Press OK to save the new field.

The SocialSecurity4Digit field should be visible when the form is in read mode while the SocialSecurityNumber field should not be displayed. In edit mode, the visibility of the fields will be reversed.

In the Project Explorer, right-click on Employees / Views / editForm1 / c1 – Employees category node, and select New Data Field option.

Use the following configuration:

Property	Value
Field Name	SocialSecurity4Digit
Visible When	this.get_isEditing() == false

Press OK to save the data field.

In the Project Explorer, double-click on Employees / Views / editForm1 / c1 – Employees / SocialSecurityNumber data field node.

Add the following Visible When expression:

Property	Value
Visible When	this.get_isEditing() == true

Press OK to save the data field.

On the toolbar, press Browse. Navigate to the Employees page and select a record.

The field SocialSecurity4Digit is displayed when the form is in read mode.

The field SocialSecurityNumber is displayed when the form enters edit mode.

Labels: Business Rules/Logic, Security, User Interface, Web Application Generator

Sunday, June 3, 2012Print Subscribe

Static Text with SQL Business Rules

The “Static” text mode property example copies the Unit Price from the selected product into the order detail, such as in the form below.

Use SQL Business Rules if you need to perform calculations when copying the data.

Let’s apply a 15% premium on the Unit Price for every order detail.

First, we need to clear the Copy instructions. Start the Project Designer. In the Project Explorer, switch to the Controllers tab. Double-click on OrderDetails / Fields / ProductID field node.

Clear the following property:

Property	New Value
Copy	N/A

Press OK to save the field. In the Project Explorer, double-click on OrderDetails / Fields / UnitPrice field node.

Change the following properties:

Property	New Value
The value of this field is calculated by a business rule expression.	True
Context Fields	ProductID

Press OK to save the field.

Next, let’s create the business rule to calculate the Unit Price. Right-click on OrderDetails / Business Rules node, and click on New Business Rule.

Use the following properties:

Property	Value
Command Name	Calculate
Type	SQL
Phase	Execute
Script	select @UnitPrice = UnitPrice * 1.15 from Products where ProductID = @ProductID

Press OK to save the business rule. On the tool bar, press Browse to generate the application.

Navigate to the Order Details page, and create a new record. Select a product, and you will notice that the Unit Price has been marked up by 15%.

Labels: Business Rules/Logic, User Interface, Web Application Generator

Friday, June 1, 2012Print Subscribe

Configure a Static Text Box

In some situations, it may not be wise to allow the user to change certain fields, even though they are updatable. For example, when creating an order detail in a Northwind web application, the Unit Price should be copied from the selected Product. Users should not be allowed to alter the Unit Price.

If you mark the field as read-only, then it will not be written to the database when the record is saved. Change the Text Mode property of the field to “Static” if you don’t want the users to edit the value but still want the field value saved to the database.

Start the Project Designer. Double-click on Customers / Order Details / container1 / view1 / createForm1 / c1 – New Order Details / UnitPrice data field node.

Change the following property:

Property	New Value
Text Mode	Static

Press OK to save the data field. Next, we’ll need to copy the Unit Price from Products to Order Details.

In the Project Explorer, double-click on Customers / Order Details / container1 / view1 / createForm1 / c1 – New Order Details / ProductID / ProductID field node.

Make the following change:

Property	New Value
Copy	UnitPrice=UnitPrice

Press OK to save the field. On the tool bar, press Browse.

When the web application opens in the browser, navigate to Order Details page and create a new record. The Unit Price data field is no longer editable by the end user.

Select a Product using the Product Name lookup. The Unit Price will be copied over into the order detail.

Labels: Business Rules/Logic, User Interface, Web Application Generator