Evjen c04.tex V2 - 01/28/2008 12:45pm Page 224 Chapter 4: Validation Server Controls end user clicks a button on the page. Listing 4-25 shows an example of separating the validation controls on a user group page into different buckets. Listing 4-25: Using the ValidationGroup property < %@ Page Language="VB" % > < html xmlns="http://www.w3.org/1999/xhtml" > < head runat="server" > < title > Validation Groups < /title > < /head > < body > < form id="form1" runat="server" > < div > < h1 > St. Louis .NET User Group < /h1 > < p > Username: < asp:TextBox ID="TextBox1" Runat="server" >< /asp:TextBox > &nbsp; Password: < asp:TextBox ID="TextBox2" Runat="server" TextMode="Password" >< /asp:TextBox > &nbsp; < asp:Button ID="Button1" Runat="server" Text="Login" ValidationGroup="Login" / > < br / > < asp:RequiredFieldValidator ID="RequiredFieldValidator1" Runat="server" Text="* You must submit a username!" ControlToValidate="TextBox1" ValidationGroup="Login" > < /asp:RequiredFieldValidator > < br / > < asp:RequiredFieldValidator ID="RequiredFieldValidator2" Runat="server" Text="* You must submit a password!" ControlToValidate="TextBox2" ValidationGroup="Login" > < /asp:RequiredFieldValidator > < p > Our main meeting is almost always held on the last Monday of the month. Sometimes due to holidays or other extreme circumstances, we move it to another night but that is very rare. Check the home page of the web site for details. The special interest groups meet at other times during the month. Check the SIG page and visit their individual sites for more information. You can also check our calendar page for a summary of events. < br / > < /p > < h2 > Sign-up for the newsletter! < /h2 > < p > Email: < asp:TextBox ID="TextBox3" Runat="server" >< /asp:TextBox > &nbsp; < asp:Button ID="Button2" Runat="server" Text="Sign-up" ValidationGroup="Newsletter" / > &nbsp; < br / > < asp:RegularExpressionValidator ID="RegularExpressionValidator1" Runat="server" Text="* You must submit a correctly formatted email address!" ControlToValidate="TextBox3" ValidationGroup="Newsletter" ValidationExpression=" \ w+([-+.] \ w+)*@ \ w+([ ] \ w+)* \ . \ w+([ ] \ w+)*" > < /asp:RegularExpressionValidator > < br / > 224 Evjen c04.tex V2 - 01/28/2008 12:45pm Page 225 Chapter 4: Validation Server Controls < asp:RequiredFieldValidator ID="RequiredFieldValidator3" Runat="server" Text="* You forgot your email address!" ControlToValidate="TextBox3" ValidationGroup="Newsletter" > < /asp:RequiredFieldValidator > < /p > < /div > < /form > < /body > < /html > The ValidationGroup property on this page is shown in bold. You can see that this property takes a String value. Also note that not only validation controls have this new property. The core server controls also have the ValidationGroup property because things like button clicks must be associated with specific validation groups. In this example, each of the buttons has a distinct validation group assignment. The first button on the form uses Login as a value, and the second button on the form uses Newsletter as a value. Then each of the validation controls is associated with one of these validation groups. Because of this, when the end user clicks the Login button on the page, ASP.NET recognizes that it should work only with the validation server controls that have the same validation group name. ASP.NET ignores the validation controls assigned to other validation groups. Using this enhancement, you can now have multiple sets of validation rules that fire only when you want them to fire (see Figure 4-13). Figure 4-13 225 Evjen c04.tex V2 - 01/28/2008 12:45pm Page 226 Chapter 4: Validation Server Controls Another great feature that has been added to validation controls is a property called SetFocusOnError . This property takes a Boolean value and, if a validation error is thrown when the form is submitted, the property places the page focus on the form element that receives the error. The SetFocusOnError property is used in the following example: < asp:RequiredFieldValidator ID="RequiredFieldValidator1" Runat="server" Text="* You must submit a username!" ControlToValidate="TextBox1" ValidationGroup="Login" SetFocusOnError="True" > < /asp:RequiredFieldValidator > If RequiredFieldValidator1 throws an error because the end user didn’t place a value in TextBox1 ,the page is redrawn with the focus on TextBox1 , as shown in Figure 4-14. Figure 4-14 Note that if you have multiple validation controls on your page with the SetFocusOnError property set to True , and more than one validation error occurs, the uppermost form element that has a validation error gets the focus. In the previous example, if both the username text box ( TextBox1 ) and the password text box ( TextBox2 ) have validation errors associated with them, the page focus is assigned to the username text box because it is the first control on the form with an error. 226 Evjen c04.tex V2 - 01/28/2008 12:45pm Page 227 Chapter 4: Validation Server Controls Summary Validation controls are a welcome addition for those developers moving from Active Server Pages to ASP.NET. They bring a lot of functionality in a simple-to-use package and, like most things in the .NET world, you can easily get them to look and behave exactly as you want them to. Remember that the purpose of having forms in your applications is to collect data, but this data collection has no meaning if the data is not valid. This means that you must establish validation rules that can be implemented in your forms through a series of different controls — the validation server controls. This chapter covered various validation controls in detail, including ❑ RequiredFieldValidator ❑ CompareValidator ❑ RangeValidator ❑ RegularExpressionValidator ❑ CustomValidator ❑ ValidationSummary In addition to looking at the base validation controls, this chapter also discussed how to apply client-side and server-side validations. 227 Evjen c05.tex V2 - 01/28/2008 12:47pm Page 229 Working with Master Pages Visual inheritance is a great new enhancement to your Web pages provided by ASP.NET 3.5. This feature was introduced to ASP.NET in version 2.0. In effect, you can create a single template page that can be used as a foundation for any number of ASP.NET content pages in your application. These templates, called master pages, increase your productivity by making your applications easier to build and easier to manage after they are built. Visual Studio 2008 includes full designer support for master pages, making the developer experience richer than ever before. This chapter takes a close look at how to utilize master pages to the fullest extent in your applications and begins by explaining the advantages of master pages. Why Do You Need Master Pages? Most Web sites today have common elements used throughout the entire application or on a major- ity of the pages within the application. For instance, if you look at the main page o f the Reuters News Web site (found at www.reuters.com ), you see common elements that are used throughout the entire Web site. T hese common areas are labeled in Figure 5-1. In this screen shot, notice the header section, the navigation section, and the footer section on the page. In fact, nearly every page within the entire application uses these same elements. Even before master pages, you had ways to put these elements into every page through a variety of means; but in most cases, doing so posed difficulties. Some developers simply copy and paste the code for these common sections to each and every page that requires them. This works, but it’s rather labor intensive. However, if you use the copy-and-paste method, whenever a change is required to one of these common sections of the application, you have to go into each and every page and duplicate the change. That’s not much fun and an ineffective use of your time! In the days of Classic Active Server Pages, one popular o ption was to put all the common sections into what was called an include file. You could then place this file within your page like this: < ! #include virtual="/myIncludes/header.asp" > Evjen c05.tex V2 - 01/28/2008 12:47pm Page 230 Chapter 5: Working with Master Pages Figure 5-1 The problem with using include files was that you had to take into account the newly opened HTML tags in the header include file. These tags had to be closed in the main document or in the footer include file. It was usually difficult to keep all the HTML tags in order, especially if multiple people worked on a project. Web pages sometimes displayed strange results because of inappropriate or nonexistent tag closings or openings. It was also difficult to work with include files in a visual designer. Using include files didn’t allow the developer to see the entire page as it would appear in a browser. The developer ended up developing the page in sections and hoping that the pieces would come together as planned. Many hours were wasted ‘‘chasing tables’’ opened in an include file and possibly closed later! 230 Evjen c05.tex V2 - 01/28/2008 12:47pm Page 231 Chapter 5: Working with Master Pages With the introduction of ASP.NET 1.0 in 2000, developers started using user controls to encapsulate common sections of their Web pages. For instance, you could build a Web page that included header, navigation, and footer sections by simply dragging and dropping these sections of code onto each page that required them. This technique worked, but it also raised some issues. Before Visual Studio 2005 and ASP.NET 2.0, user controls caused problems similar to those related to include files. When you worked in the design view of your Web page, the common areas of the page displayed only as gray boxes in Visual Studio .NET 2002 and 2003. This made it harder to build a page. You could not visualize what the page you were building actually looked like until you compiled and ran the completed page in a browser. User controls also suffered from the same problem as include files — you had to match up the opening and closing of your HTML tags in two separate files. Personally, we prefer user controls over include files, but user controls aren’t perfect template pieces for use throughout an application. You will find t hat Visual Studio corrects some of the problems by rendering user-control content in the design view. User controls are ideal if you are including only small sections on a Web page; they are still rather cumbersome, however, when working with larger page templates. In light of the issue s with include files and user controls, the ASP.NET team developed the idea of master pages — an outstanding new way of applying templates to your applications. They inverted the way the developer attacks the problem. Master pages live outside the pages you develop, while user controls live within your pages and are doomed to duplication. These master pages draw a more distinct line between the common areas that you carry over from page to page and the content areas that are unique on each page. You will find that working with master pages is easy and fun. The next section of this chapter looks at some of the basics of master pages in ASP.NET. The Basics of Master Pages Master pages are an easy way to provide a template that can be used by any number of ASP.NET pages in your application. In working with master pages, you create a master file that is the template referenced by a subpage or content page. Master pages use a .master file extension, whereas content pages use the .aspx file extension you’re used to; but content pages are declared as such within the file’s Page directive. You can place anything you want to be included as part of the template in the .master file. This can include the header, navigation, and footer sections used across the Web application. The content page then contains all the page content except for the master page’s elements. At runtime, the ASP.NET engine combines these elements into a single page for the end user. Figure 5-2 shows a diagram of how this process works. One of the nice things about working with master pages is that you can visually see the template in the IDE when you are creating the content pages. Because you can see the entire page while you are working on it, it is much easier to develop content pages that use a template. While you are working on the content page, all the templated items are shaded gray and are not editable. The only items that are alterable are clearly shown in the template. These workable areas, called content areas, originally are defined in the master page itself. Within the master page, you specify the areas of the page that the content pages can use. You can have more than one content area in your master page if you want. Figure 5-3 shows the master page with a couple of content areas shown. 231 Evjen c05.tex V2 - 01/28/2008 12:47pm Page 232 Chapter 5: Working with Master Pages Figure 5-2 Figure 5-3 232 Evjen c05.tex V2 - 01/28/2008 12:47pm Page 233 Chapter 5: Working with Master Pages If you look at the screenshot from Figure 5-3, you can sort of see two defined areas on the page — these are content areas. The content area is represented in the design view of the page by a light dotted box that represents the ContentPlaceHolder control. Also, if you hover your mouse over the content area, you will see the name of the control appear above the control (although lightly). This hovering is also shown in action in Figure 5-3. Companies and organizations will find using master pages ideal, as the technology closely models their typical business requirements. Many companies have a common look and feel that they apply across their intranet. They can now provide the divisions of their company with a .master file to use when creating a department’s section of the intranet. This process makes it quite easy for the company to keep a consistent look and feel across its entire intranet. Coding a Master Page Now look at building the master page shown previously in Figure 5-3. You can create one in any text-based editor, such as Notepad or Visual Web Developer Express Edition, or you can use the new Visual Studio 2008. In this chapter, you see how it is done with Visual Studio 2008. Master pages are added to your projects in the same way as regular .aspx pages — choose the Master Page option when you add a new file to your application, as shown in Figure 5-4. Figure 5-4 Because it’s quite similar to any other .aspx page, the Add New Item dialog enables you to choose from a master page using the inline coding model or a master page that places its code in a separate file. Not placing your server code in a separate file means that you use the inline code model for the page you are creating. This option creates a single .master page. Choosing the option to place your code in a separate file means that you use the new code-behind model with the page you are creating. Selecting the check box ‘‘Place code in separate file’’ creates a single .master page, along with an associated .master.vb or 233 Evjen c05.tex V2 - 01/28/2008 12:47pm Page 234 Chapter 5: Working with Master Pages .master.cs file. You also have the option of nesting your master page within another master page by selecting the Select master page option, but this is covered later in this chapter. A sample master page that uses the inline-coding model is shown in Listing 5-1. Listing 5-1: A sample master page < %@ Master Language="VB" % > < script runat="server" > < /script > < html xmlns="http://www.w3.org/1999/xhtml" > < head runat="server" > < title > My Company Master Page < /title > < asp:ContentPlaceHolder id="head" runat="server" > < /asp:ContentPlaceHolder > < /head > < body > < form id="form1" runat="server" > < table cellpadding="3" border="1" > < tr bgcolor="silver" > < td colspan="2" > < h1 > My Company Home Page < /h1 > < /td > < /tr > < tr > < td > < asp:ContentPlaceHolder ID="ContentPlaceHolder1" runat="server" > < /asp:ContentPlaceHolder > < /td > < td > < asp:ContentPlaceHolder ID="ContentPlaceHolder2" runat="server" > < /asp:ContentPlaceHolder > < /td > < /tr > < tr > < td colspan="2" > Copyright 2008 - My Company < /td > < /tr > < /table > < /form > < /body > < /html > This is a simple master page. The great thing about creating master pages in Visual Studio 2008 is that you can work with the master page in code view, but you can also switch over to design view to create your master pages just as any other ASP.NET page. 234 . Figure 5 -3 shows the master page with a couple of content areas shown. 231 Evjen c 05. tex V2 - 01 /28/ 2008 12:47pm Page 232 Chapter 5: Working with Master Pages Figure 5- 2 Figure 5 -3 232 Evjen c 05. tex. file within your page like this: < ! #include virtual="/myIncludes/header .asp& quot; > Evjen c 05. tex V2 - 01 /28/ 2008 12:47pm Page 230 Chapter 5: Working with Master Pages Figure 5- 1 The. ASP. NET 3. 5. This feature was introduced to ASP. NET in version 2.0. In effect, you can create a single template page that can be used as a foundation for any number of ASP. NET content pages in your