Wrox Professional Web Parts and Custom Controls with ASP.NET 2.0 phần 2 pot

❑ Listing books: One control might provide a single column with limited options for sorting the list, another control could support complex sorting options, another control might format the user into a rigid grid format with a single line for each book, and yet another control might allow the list to “snake” through multiple columns, allowing more books to be listed on a page. ❑ Displaying book information: Different controls might vary in the amount of information displayed about a book or which information stands out. One control might be formatted so that information about book size and weight stands out for retail buyers concerned about reducing shipping costs — information that the typical reader isn’t interested in. With those controls created, you could add a page to your application that consists of two areas: ❑ One area at the top of the page to place one of the search criteria controls ❑ An area below that to put one of the controls for listing books Users could draw from your toolkit of Web Parts to build the search page that they want. Users would be able to put the search criteria Web Part that most meets their needs at the top of the page and put the listing Web Part they want below that. To work with the listing control, they could add the book infor- mation Web Part that supports them best. This is a solution aimed purely at giving users the opportunity to create the application they need. Providing for Personalization In order to implement customization, you also need personalization. Your users won’t be happy if they have to recreate their application each time that they return to your site, or if, when they return, they get some other user’s customization. Customization is of no use unless the application remembers what changes a user has made and associates those changes with the user that made them. Fortunately, ASP.NET 2.0 comes with a personalization framework. The ASP.NET 2.0 personalization framework allows you to implement an application that tracks users and the choices they make so that when the users return to your application, they find their own customizations waiting for them. Each user is connected to his customized application after he logs on with little effort on your part. This description makes personalization sound like a “nice-to-have” feature. In fact, personalization is really just the extension of identity-based security, which is essential in building an application. When users access your Web site, they are automatically logged on to your Web site’s server. The logging in process assigns the user an identity, even if it’s only the default “anonymous user” assigned by IIS. If you’ve turned off the capability to log on as the anonymous user, then the user may be silently logged on using whatever credentials are currently available (for instance, the user ID and password that the user logged on to his workstation with). If no valid credentials are available, the user may be asked to enter a user ID and password. After the user has logged on to your site’s server, your application may have an additional level of security that requires the user to enter a user ID and password into your application’s login page. 18 Chapter 1 05_57860x ch01.qxd 10/4/05 9:26 PM Page 18 All of this work, both in the infrastructure that supports your Web application and in the application code behind your login page, has just one purpose: to establish who the user is (the user ID) and to authenticate that claim (the password). Once a user is authenticated, she is then authorized to perform specific activities. Whatever mechanism is used to authenticate the user, when the process is completed successfully, the user has been assigned an identity. From this point of view, security is just the base level of personalization; security assigns an identity that is authorized to perform some activities (and forbidden to perform others). Personalization extends this security feature up from the ASP.NET infrastructure and into the application domain. Personalization allows you to manage your application on the basis of who the user is. The identity you are assigned when you log onto the Web server is used just within the application. When your code accesses other services (for example, reading or writing a database), those accesses are normally performed by an identity that represents ASP.NET. (On Windows 2003, this identity is called NETWORK SERVICE; on other versions of Windows the identity is called ASPNET.) In your applica- tion’s Web.Config file you can turn on impersonation, which causes the ASP.NET application to adopt the identity used to log on to the server: the anonymous user if anonymous access is enabled, the user’s identity if anonymous access is not enabled. Understanding the Personalization Framework The good news is that the personalization framework will take care of itself—by and large you can just build on the personalization framework and count on it to work. However, there are some decisions that you will need to make as part of setting up a Web site (for example, selecting the correct provider for your site). In order to make those decisions you need to understand the components of the personalization framework. The personalization framework has three main components: ❑ Login controls ❑ Membership providers ❑ Profile services and providers The first components of the personalization framework that a user encounters are ASP.NET 2.0’s new login and user controls. Rather than write all the code necessary to log in a user, you can simply drag and drop the new login controls to a Web page. These controls handle all the typical tasks associated with the log on process (including sending forgotten passwords to users). For personalization, these controls allow a user to be assigned an identity. Separate from this process, the site administrator has to register with the personalization datastore the identities that users can be assigned. Figure 1-6 illustrates the three elements of the personalization framework: login controls, membership providers, and profile services. 19 Creating Your Own Controls 05_57860x ch01.qxd 10/4/05 9:26 PM Page 19 Figure 1-6 Within the area of user management, some other features of SharePoint have also migrated into ASP.NET 2.0. Within SharePoint, it’s possible for authorized users to create new SharePoint sites, new users, new pages, and perform other administrative tasks. In ASP.NET 2.0, as part of the personalization framework, it’s possible to implement user management functions within the site itself (although you still can’t create a whole new Web site from within an application). ASP.NET even comes with a set of pre-defined user administration pages that you can incorporate into your site. Logging in is more than just assigning identities. For sites that have a small number of users, implement- ing personalization on an identity-by-identity basis is a viable choice. However, as the number of identities increases, the costs of maintaining personalized information increases. While costs increase with the number of identities, the benefits of personalization don’t increase. In all likelihood, the cus- tomizations made for one identity will be applicable to other identities. In any user community, you can probably break your user community up into several groups. This can be handled by assigning individual users to roles and implementing customizations on a role-by-role (group) basis. As a result, you need a mechanism that not only assigns identities to users but also assigns users to roles. The next component of the personalization framework, the membership provider, handles this. The membership provider is the glue that binds the site to the users that access the site and binds the site’s functionality to the various user roles. Membership providers also handle all the tasks around storing user and role information. Two membership providers come with ASP.NET 2.0: one for storing informa- tion in Microsoft SQL Server and one for storing information in a Jet database. If you want, you can even build your own membership provider to connect to other data stores. A provider is a component that extends or replaces some existing ASP.NET function. Any part of ASP.NET that is implemented through a provider model can be enhanced or replaced with a provider written by you (or some third party, such as IBM’s Tivoli for transaction management). Once you have built a new provider, you plug it in to the list of available providers and select it when you build your application (which is why providers are said to be “pluggable”). The main requirement of a provider is that it has to reproduce the interface (methods, properties, events) for the provider that it extends or replaces. However, what happens behind that interface is up to the developer that creates the provider. 20 Chapter 1 05_57860x ch01.qxd 10/4/05 9:26 PM Page 20 The final component of the personalization framework is the profile service. A profile is all the data associated with a specific identity. The profile service allows you to store and retrieve data for a particu- lar identity or role. To access the profile service, you need a profile provider that handles all the data access for you. The profile service is very flexible: you can store any data from simple datatypes (for example, strings) right up to an object (provided that the object can be serialized). In addition, saving and restoring data from the profile is handled for you automatically. Summary In this chapter you’ve learned about the two types of controls that you can use in ASP.NET: ❑ User controls: A combination of content, static HTML, ASP.NET tags, and code, built using the same tools that you use to create Web pages. ❑ Custom controls/WebParts: A code-only solution, very similar to ASP.NET custom controls. Unlike custom controls, you cannot inherit from other controls when building a Web Part. These controls are the focus of this book. By the end of this book you’ll have learned how to build the more powerful and flexible custom con- trols. I also show you how to use these controls as Web Parts and how to extend custom controls to let users customize your site. Along the way, you’ll also see how easy it is to build user controls—and both how to add custom control features to user controls and use them as Web Parts. While it’s good to know about controls, what’s important to you is what you do with those controls. You’ve seen how these ASP.NET tools support two different scenarios: ❑ Reusability: Controls support reusability in the user interface (or presentation) layer rather than in the business rules layer. Like other reusability tools, controls enable you to provide a standardized set of services and improve your own productivity. ❑ Customization: Web Parts allow you to support customization to a degree that simply wasn’t possible in earlier versions of ASP and ASP.NET. With Web Parts, you can allow your users to create customized versions of existing pages, or to create pages that were not intended to be included in the application. While this empowers your users, it also opens up a whole new set of challenges for the developer, both in determining what Web Parts the user community will need and ensuring that those Web Parts will work in all the different ways that users want. Finally, in order to support customization, you also need personalization: the ability to keep track of a user’s choices, remember those changes from one session to another, and connect the user to his cus- tomized pages. Personalization is the extension of identity-based security into application development. Over the rest of this book, you’ll see how to build custom controls, user controls, and Web Parts. The personalization framework allows you to store, as part of a profile, the Web Part customizations associated with some identity. The membership provider allows you to keep track of which identities are being used. The login controls assign identities to users. 21 Creating Your Own Controls 05_57860x ch01.qxd 10/4/05 9:26 PM Page 21 05_57860x ch01.qxd 10/4/05 9:26 PM Page 22 Creating Customizable Pages The capability to add customization to your Web application using Web Parts is completely new in ASP.NET 2.0. Before plunging in to the details of creating controls, it’s worthwhile to take the time to understand what customization means to you and your users. Consider these four questions: ❑ How much work is required to enable customization? How do you turn it on? ❑ How do I take advantage of customization in my applications? ❑ Do I need to write a lot of specialized code to create customizable pages? ❑ What customization can the user expect to be able to do with a Web page? This chapter shows you the detailed answers to all four of these questions, but here are the short answers: To turn on customization you just need to drag a single control onto our page. You can implement customization in your application just by dragging and dropping other standard ASP.NET controls to a page. And you don’t have to write much code at all — two or three lines of code will allow your users to add and remove controls from the page, configure the appearance of the controls, and move controls from one part of your page to another. From the more detailed answers in this chapter, you’ll learn how to ❑ Create a customizable ASP.NET page ❑ Use the Web Part framework controls that come with ASP.NET ❑ Determine which parts of the page are available for customization ❑ Add standard ASP.NET server-side controls to let your users customize the page ❑ Customize a Web Part–enabled page 06_57860x ch02.qxd 10/4/05 9:24 PM Page 23 Chapter 2 In this chapter, you use the standard server-side controls that come with ASP.NET 2.0 on a customizable page so that you can see that you don’t need to create specialized Web Part controls to take advantage of customization. This is critical for your work as a developer creating controls: to create controls that support customization, you need to understand how the various tools that make up the Web Parts framework work together. These tools form the environment that your code will integrate with when you start creating your own controls. Finally, you also get a glimpse of the kind of customizations that become available when you do add Web Part features to your own controls. The Web Part Framework Controls New to the Visual Studio 2005 Toolbox is a tab called WebParts. In this tab you find the dozen Web Part infrastructure controls that make up the Web Part framework. I refer to these as the Web Part framework controls (or just the framework controls) to distinguish them from the controls that you’ll create or the standard ASP.NET controls that come with .NET. These framework controls include: ❑ WebPartManager: The control that enables a page for customization. ❑ Zones: These controls define the sections of a page that users can customize. Different kinds of WebPartZones support different kinds of Web Part controls, as follows: ❑ WebPartZone: For holding controls (either standard ASP.NET controls or controls that you create). ❑ CatalogZone: For holding Web Part framework controls that list the controls that you can add to WebPartZones. ❑ EditorZone: For holding editors that allow you to modify controls on the page. ❑ Editors: The tools that allow the user to set properties on a control or otherwise modify a control. ❑ AppearanceEditorPart: Allows the user to set the values of specific properties related to the way that a control is displayed. ❑ BehaviorEditorPart: Allows the user to set the values of specific properties on a control in shared mode, which causes the changes to be made for all users instead of just for the user making the change. ❑ LayoutEditorPart: Allows the user to move controls from one location on the page to another. ❑ PropertyGridEditorPart: Allows the user to set any custom properties on a control (that is, those properties on a custom control that are not inherited from a base control). ❑ Catalogs: The tools that list the controls that can be added to the page, including: ❑ DeclarativeCatalogPart: Lists controls that are declared in the HTML in the page but haven’t yet been added to the page. ❑ PageCatalogPart: Lists controls that are already added to the page but aren’t visible to the user (controls that are closed). ❑ ImportCatalogPart: Lists controls that can be added to the page by importing from files on your server. 24 06_57860x ch02.qxd 10/4/05 9:24 PM Page 24 ❑ ConnectionsZone: Holds connection objects that represent connections between controls in a Web Part Zone. Creating a Customizable Page In Visual Studio 2005, you begin creating a customizable page for your application by dragging a WebPartManager from the toolbox and onto the page that you want to enable for customization. A WebPartManager control has no visible user interface at run time (at design time the WebPartManager appears as a plain gray box); the control is just there to support customization. If you get the message “The operation could not be completed. Unspecified error” when dragging and dropping the WebPartManager, or if you’re not working with Visual Studio .NET, you can add a WebPartManager to a page by putting this tag in your page right after the open <form> tag: <asp:webpartmanager id=”WebPartManager1” runat=”server” /> Adding a WebPartManager not only supports customization on the page but also activates the necessary personalization support for your ASP.NET application, including creating a SQL Server (or SQL Server Express) database to hold your application’s personalization information when you first debug your application. The next time you start Visual Studio 2005, you’ll see that the App_Data folder in Solution Explorer will have an entry for the ASPNETDB.MDF file. If the database doesn’t appear in Solution Explorer, or you don’t want to wait until you restart Visual Studio 2005, you can add the database to Solution Explorer manually: 1. Right-click on the App_Data entry in Solution Explorer. 2. Select Add Existing Item. The Add Existing Item dialog box opens. 3. Open the App_Data subdirectory. You should find the ASPNETDB.MDF directory there. Depending on the speed of your computer, it’s possible that your Web application will time out before your personalization database is created the first time you test the page. If so, just restart your Web application and your database will be created by the time that you restart. You should add the WebPartManager control to any page where you want to use the other framework components first, before adding any other Web Part control. Attempting to use the other Web Part framework controls on a page without a WebPartManager just generates a run time error when you attempt to view the page in a browser. If you add a WebPartManager to a page after adding other Web Part framework controls, you must make sure that the WebPartManager is at the top of the page, before any of the other framework controls. 25 Creating Customizable Pages 06_57860x ch02.qxd 10/4/05 9:24 PM Page 25 Chapter 2 4. Click the ASPNETDB.MDF file to select it. 5. Click the Add button to add the file to Solution Explorer. Clicking the plus sign beside the MDF file entry will let you explore the tables that hold personalization data as you would with any other database that you attach to your project. Because the personalization data is held in a database on the server (rather than, for instance, cookies that are sent to the browser) a user’s customizations are maintained even if the user accesses the site from different browsers or different computers. While this is all that you need to get started with personalization and customization, in Chapter 10 you learn more about what you can with ASP.NET’s personalization infrastructure (including how to specify which database management system will store your site’s personalization data). With the WebPartManager on the page, you must next set up the zones on the page where customization will be allowed. Because customization happens only within these zones, to protect parts of your page from customization simply make sure those parts of the page aren’t in a zone. In order to create a zone in Visual Studio 2005, you just drag a WebPartZone control onto your Web page. The samples used in this chapter are added to a page called CustomizablePage.ASPX. After the WebPartZone is on the page, you can control the position of the zone by selecting Layout ➪ Position ➪ Absolute from the Visual Studio menus and dragging the WebPartZone to where you want it. You can resize the WebPartZone by dragging its sides as you would with any other control. You can place as many WebPartZones onto a page as you want. Figure 2-1 shows a page with three WebPartZones. Figure 2-1 If you’re working outside of Visual Studio 2005, you can add WebPartZones to your page using the asp:WebPartZone element. The following code shows the tags for the page shown in Figure 2-1: 26 06_57860x ch02.qxd 10/4/05 9:24 PM Page 26 <body> <form id=”form1” runat=”server”> <div> <asp:WebPartZone ID=”WebPartZone1” Style=”z-index: 57; left: 10px; position: absolute; top: 15px” Runat=”server” Width=”342px” Height=”81px”> </asp:WebPartZone> <asp:WebPartZone ID=”WebPartZone2” Style=”z-index: 56; left: 10px; position: absolute; top: 96px” Runat=”server” Width=”126px” Height=”318px”> </asp:WebPartZone> <asp:WebPartZone ID=”WebPartZone3” Style=”z-index: 55; left: 136px; position: absolute; top: 96px” Runat=”server” Width=”216px” Height=”320px”> </asp:WebPartZone> </div> </form> </body> Each WebPartZone consists of a header area and an area where controls can be added. The contents of the header can be set using the HeaderText property of the WebPartZone. In Figure 2-1, the HeaderText properties of the three zones have been set to Search, Detail, and List. In the figure, none of these con- trols has had any custom controls added, so the WebPartZone displays an empty area for you to drag your control to. You can modify the WebPartZone to display text in this area when no control is present (for example, “Drag a WebPart here”) through the EmptyZoneText property of the WebPartZone. You can control the appearance of this “empty” area through the EmptyZoneTextStyle property. A zone’s HeaderText and EmptyPartText aren’t displayed just at design time. As you’ll see later in this chapter, the EmptyPartText can be visible to your users when they are customizing a page. So getting the EmptyPartText/EmptyZoneTextStyle and HeaderText/HeaderStyle correct can be an important design decision. Adding Controls to a Zone After you’ve added a WebPartZone to a page, in Visual Studio .NET you can add controls into the lower part of the zone by dragging them from the toolbox. Figure 2-2 shows a WebPartZone that has had a text box and a button dragged into it. The bad news is that after you drag a control into a zone, you can’t position the control within the zone—controls are inserted either beside or underneath each other (this is controlled by the zone’s LayoutOrganization property). You can’t use absolute positioning within a zone. In this chapter, only standard ASP.NET controls are used in a zone. However, you can put just about anything in a zone: HTML controls, plain text, custom controls, and (as you’ll see) user controls. 27 Creating Customizable Pages 06_57860x ch02.qxd 10/4/05 9:24 PM Page 27 [...]... Creating Customizable Pages Figure 2- 19 This chapter showed how to use standard ASP.NET controls as Web Parts To take advantage of the capability to connect Web Parts or to export and import Web Parts, you must use full-fledged Web Part controls The framework controls that support importing and exporting are covered in Chapter 11, as is how to create Web Parts that can work with the framework controls. .. number of customizations are available Like Web Parts, the customization parts must be put inside zone controls In addition, zones and parts are matched sets: Zone controls are customized to support a specific set of parts; parts can be added only to the zones that support those parts For instance, the various editing parts (parts that allow users to customize the properties and appearance of controls) ... see how to create Web Parts that support more customizations than are possible with the standard ASP.NET controls Customization Tool Controls In order to support more than just dragging controls between zones, you need to add additional controls to the page Controls that are used to customize other controls are referred to as parts Because this chapter uses just the standard ASP.NET controls, only a... still minimized ASP.NET has kept track of your customization This is a very simple customization application Before you can take full advantage of the customization facilities in ASP.NET, you’ll need to drill a little deeper into zones and controls and how Web Parts interact with them 31 Chapter 2 Figure 2- 4 Configuring a Zone WebPartZones support the standard properties for all WebForm controls (such... catalog to display a WebPartsTemplate (see Figure 2- 18) You can now drag controls out of the toolbox and into the WebPartsTemplate Figure 2- 17 You do not need to add the user control to the page with the DeclarativeCatalogPart You can also add controls to a DeclarativeCatalogPart by setting its WebPartsListUserControlPath to the name of a user control that has Web Parts on it (the Web Parts must be sitting... inside the GenericWebPart So, in this chapter, the controls in the zone are treated as if they were Web Parts rather than ASP.NET controls wrapped inside a Web Part Once you start creating your own Web Parts, you’ll be able to create Web Parts that contain multiple ASP.NET controls You’ll also see how to access the methods and properties of Web Part objects even at design time Accessing Controls in a Zone... Support the various customization options using additional Web Part zones and parts Creating a basic Web Part is covered in Chapter 5 Programming with WebPartZones and the other Web Part controls that ship with Visual Studio NET is covered in more depth in Chapters 9, 10, and 11 However, this chapter has described the basic environment for the Web Parts and given you a better idea of what customization is... Me.znDataEntry.WebParts(“txtTopic”).Title = “Search” In C#: this.znDataEntry.WebParts[“txtTopic”].Title = “Search”; 29 Chapter 2 Figure 2- 3 When a control is accessed through the WebParts collection, a WebPart object is returned You can use this object to set properties relevant to a Web Part, as this Visual Basic 20 05 code does by setting the Title property: Dim wp As WebPart wp = Me.znSearch.WebParts(“TextBox1”)... page ❑ Add new controls to the page from a catalog of controls Figure 2- 10 Not all of the customizable options that are available can be used with ASP.NET controls (for instance, you can update a property only at run time if the property has been set up to support that customization) The following section introduces the basics of customization and what can be done with the standard ASP.NET controls In... catalog tools include a list of available controls, for instance, and so the CatalogZone’s properties include a CatalogItemStyle that controls the style applied to each item in the list 50 Creating Customizable Pages Summar y In this chapter you learned how to create a customizable page in ASP.NET 2. 0, using the Web Part framework controls distributed with ASP.NET 2. 0 You’ve seen how you can enable users . used. The login controls assign identities to users. 21 Creating Your Own Controls 05 _57860x ch01.qxd 10/ 4 /05 9 :26 PM Page 21 05 _57860x ch01.qxd 10/ 4 /05 9 :26 PM Page 22 Creating Customizable Pages The. users customize the page ❑ Customize a Web Part–enabled page 06 _57860x ch 02 . qxd 10/ 4 /05 9 :24 PM Page 23 Chapter 2 In this chapter, you use the standard server-side controls that come with ASP. NET. 20 05, you can add WebPartZones to your page using the asp: WebPartZone element. The following code shows the tags for the page shown in Figure 2- 1: 26 06 _57860x ch 02 . qxd 10/ 4 /05 9 :24 PM Page 26 <body> <form