The user interface is built upon Field Templates, user control files that ensure the user interface conforms to your business logic. Each Field Template handles a specific data type and there can be several setup for a single data type to handle the nuances of your application. These files are fully editable and you can add new ones, so you can customize the user interface as needed. They are shared by all web forms, providing a consistent user interface.

Here’s a look inside of Currency_Edit.ascx, the Field Template for editing Currency data types:

<%@ Control Language="C#" Inherits="PeterBlum.DES.BLD.CurrencyEditFieldTemplate" %>
<script runat="server">

  protected void Page_Init(object sender, EventArgs e)
  {
    SetUpEditableDataControl(CurrencyTextBox1);
    SetUpBLDDataFieldValidators(BLDDataFieldValidators1);
  }
</script>

<des:CurrencyTextBox id="CurrencyTextBox1" runat="server" />
<des:BLDDataFieldValidators id="BLDDataFieldValidators1" runat="server" />

It has two web controls. CurrencyTextBox comes with Peter’s Data Entry Suite to provide input for currency values. A Field Template can support any kind of input control, including those from a third party. In fact, BLD includes Field Templates for Telerik’s RadControls for ASP.NET AJAX and the AJAX Controls Toolkit. BLDDataFieldValidators installs the validator web controls based on the business logic, so you don’t have to worry about the UI matching the business requirements.

You use the BLDDataField control whereever you want a Field Template to be inserted into your Web Form. Specify the DataField in its DataField property. (Remember that a DataField is the property name in the Entity class.) It will choose a Field Template based on the DataTypeAttribute or field's actual type and from the data entry mode (readonly, edit, insert). You can override that by specifying the Field Template's name in the UIHint property (omitting the extension.)

<des:BLDDataField id="ProductName" runat="server" DataField="ProductName" />
<des:BLDDataField id="SupplierURL" runat="server" DataField="Supplier.HomePage" UIHint="Url" />

When you want to change how a Field Template works, it may seem obvious to just go an edit its file. Before you do that, evaluate the many ways Field Templates let the Web Form developer customize it.

• Each Field Template User Control class defines public properties that can you can assign using the BLDDataField's TemplateProperties collection. More
• The Named Styles lets you override default styles on controls inside of the Field Template and Pattern Templates. More
• Error messages come from the business logic’s ValidatorAttributes. You can override them with the ErrorMessages property on various controls. There are also numerous settings to format validation error messages and draw the users attention to them. More
• Field Template Behaviors can expand the features of some or all Field Templates without you modifying the Field Template’s code. BLD installs several Behaviors which you can modify to determine the ideal interface. More
• Modify any aspect of the controls contained in the Field Template using several event handlers on the BLDPageManager control. More
• Modify the business logic settings passed to your Field Template using the BLDPageManager.CustomizeDataField event handler.

<des:BLDDataField id="ProductName" runat="Server" DataField="ProductName">
   <NamedStyles>
     <des:NamedStyle Style="font-size:larger; font-weight:bold;"  />
   </NamedStyles>
</des:BLDDataField>
<des:BLDDataField id="SupplierHomePage" runat="server" DataField="Supplier.HomePage">
   <TemplateProperties>
     <des:UrlReadOnlyFieldTemplateProperties UrlText="{DATAFIELD:Supplier.CompanyName}" /> 
   </TemplateProperties>
   <Behaviors>
     <des:HintFieldTemplateBehavior Hint="Located in {DATAFIELD:CompanyLocation}"
       ApplyHintInReadOnlyMode="True" SharedHintFormatterName="AliceBlue-Small"
       ButtonLocation="AfterDataControl" UseOnlyButton="true"
       ButtonImageURL="~/Images/Info.gif" ButtonImageAlign="Bottom" />
   </Behaviors>
</des:BLDDataField>

BLD includes the following Field Templates, many of which utilize data entry controls from the Peter's TextBoxes and Peter's Date and Time modules of Peter's Data Entry suite.

If you use Telerik RadControls for ASP.NET AJAX, it also provides Field Templates that merge the RadControls data entry controls with the DES Validation Framework as shown here:

If you use Ajax Control Toolkit, it provides these Field Templates: