qr code c# source SaveViewState and LoadViewState preserves the default view state in C#.NET

Making QR Code ISO/IEC18004 in C#.NET SaveViewState and LoadViewState preserves the default view state

Listing 4.2 SaveViewState and LoadViewState preserves the default view state
Drawing QR-Code In C#
Using Barcode encoder for Visual Studio .NET Control to generate, create QR Code 2d barcode image in .NET framework applications.
www.OnBarcode.com
QR Scanner In C#.NET
Using Barcode reader for .NET Control to read, scan read, scan image in .NET framework applications.
www.OnBarcode.com
protected override object SaveViewState() { object state = new object[2]; object[0] = counter; object[1] = base.SaveViewState(); return state; } protected override void LoadViewState(object savedState) { if (savedState != null) { object[] state = (object[]) savedState; counter = (int)state[0]; base.LoadViewState(state[1]); } }
PDF-417 2d Barcode Generator In Visual C#.NET
Using Barcode generator for Visual Studio .NET Control to generate, create PDF 417 image in VS .NET applications.
www.OnBarcode.com
Draw 2D In Visual C#.NET
Using Barcode encoder for .NET Control to generate, create 2D Barcode image in .NET framework applications.
www.OnBarcode.com
The SaveViewState method creates an object array that stores the custom value and the default view state. The method then returns this array. The view state is loaded by LoadViewState, which casts the savedState argument into an object array. The first value of the array is cast to your custom variable, and the second value in the array is used as an argument to the base implementation of LoadViewState.
Paint UPC-A In C#.NET
Using Barcode encoder for Visual Studio .NET Control to generate, create GS1 - 12 image in .NET framework applications.
www.OnBarcode.com
Barcode Creation In C#.NET
Using Barcode maker for .NET framework Control to generate, create Barcode image in .NET framework applications.
www.OnBarcode.com
Using validators Validators are a part of the ASP.NET Framework. They re special controls that validate the input of other controls. The validation is performed both on the server side and
Draw Data Matrix ECC200 In Visual C#
Using Barcode encoder for .NET Control to generate, create Data Matrix 2d barcode image in .NET framework applications.
www.OnBarcode.com
Making Leitcode In C#
Using Barcode maker for VS .NET Control to generate, create Leitcode image in Visual Studio .NET applications.
www.OnBarcode.com
Building the user interface
QR Code Scanner In C#.NET
Using Barcode decoder for .NET Control to read, scan read, scan image in .NET applications.
www.OnBarcode.com
Draw QR Code ISO/IEC18004 In None
Using Barcode creator for Office Excel Control to generate, create QR-Code image in Microsoft Excel applications.
www.OnBarcode.com
Figure 4.5 The Designer view in Visual Studio shows a Visual Web Part with two validated text boxes, a button, and a result label.
Painting Barcode In .NET
Using Barcode creator for ASP.NET Control to generate, create Barcode image in ASP.NET applications.
www.OnBarcode.com
Universal Product Code Version A Encoder In .NET
Using Barcode generator for Reporting Service Control to generate, create GS1 - 12 image in Reporting Service applications.
www.OnBarcode.com
on the client side for the out-of-the-box validators. You should take advantage of these controls. The problem with validators in Web Parts is that the Web Parts can be added multiple times to a page and together with other Web Parts that use validators. This can result in validation collisions if you don t set it up correctly. To resolve this problem, use the ValidationGroup property of the controls and validators. Figure 4.5 shows you a Visual Web Part that has two text boxes, a button, and a label, as well as a validator for each text box. The validators validate that the text boxes contain only a number using regular expression validators like this:
Generating Data Matrix 2d Barcode In None
Using Barcode maker for Microsoft Word Control to generate, create DataMatrix image in Word applications.
www.OnBarcode.com
Generating Barcode In Java
Using Barcode generator for Android Control to generate, create Barcode image in Android applications.
www.OnBarcode.com
<asp:RegularExpressionValidator ID= RegularExpressionValidator1 runat= server ControlToValidate= TextBox1 ErrorMessage= Must be a number ValidationExpression= \d+ > </asp:RegularExpressionValidator>
Encode DataMatrix In Visual Studio .NET
Using Barcode generation for ASP.NET Control to generate, create DataMatrix image in ASP.NET applications.
www.OnBarcode.com
Denso QR Bar Code Generator In None
Using Barcode printer for Microsoft Word Control to generate, create Quick Response Code image in Office Word applications.
www.OnBarcode.com
If you add two or more of these validator Web Parts to a page and enter invalid values in one of them and, in one of the other Web Parts, click the button, the Web Part with invalid values will invalidate the click because it can t validate. This is because the validation is done on all controls with validators on the current page when you click the button, not only in the Web Part you re clicking on. To solve the problem, you need to use the validation groups. You can t use a declarative approach and enter a name of the validation group because this name will be the same for all your Web Parts. Instead, you need to set the validation group name programmatically to get a unique value. This is a Visual Web Part, and we need to set the validation group in the user control code-behind. The code is added into an overridden OnPreRender method, as in the following listing.
Printing Barcode In .NET
Using Barcode creator for .NET framework Control to generate, create Barcode image in .NET applications.
www.OnBarcode.com
GS1 - 12 Creation In Java
Using Barcode drawer for Android Control to generate, create UCC - 12 image in Android applications.
www.OnBarcode.com
Listing 4.3 Adding dynamic validation groups to a Visual Web Part
Generating Code-39 In Objective-C
Using Barcode generation for iPad Control to generate, create Code 39 Full ASCII image in iPad applications.
www.OnBarcode.com
Creating GS1 DataBar-14 In Java
Using Barcode generator for Java Control to generate, create GS1 DataBar Stacked image in Java applications.
www.OnBarcode.com
protected override void OnPreRender(EventArgs e) { TextBox1.ValidationGroup = ClientID; TextBox2.ValidationGroup = ClientID; RegularExpressionValidator1.ValidationGroup = ClientID;
ASP.NET and Web Parts
RegularExpressionValidator2.ValidationGroup = ClientID; Button1.ValidationGroup = ClientID; base.OnPreRender(e); }
The ValidationGroup property is set on all controls and validators to the ClientID of the Visual Web Part user control. This will guarantee that the validation group name is unique within the page. The ClientID property, which exists on all controls, is an identifier generated by the ASP.NET runtime, which is guaranteed to be unique for the page. In this case, the ClientID of the Web Part is used to ensure uniqueness for the validation group.
A good practice is to disable all or some validators while in Edit mode for the Web Part or page to prevent the validators from blocking the editing operations. Using validation groups can also avoid blocking the editing operations.
Custom controls and user controls Building the UI using a large amount of controls in the Web Part might not always be the best option. Instead, consider moving some of your controls to custom server controls or user controls. This arrangement will make your code easier to understand and follow. Creating custom user controls also makes the control reusable to other Web Parts or pages that you build. If you re creating a solution and targeting the sandbox, then you can t use user controls but, instead, have to rely on creating server controls. User controls are based on ASCX pages that are deployed into the {SharePoint Root} (which isn t allowed by the sandbox). To show you how to create a user control, let s go back to our earlier validation example and create a user control consisting of a text box that only accepts integers. Start by creating a Visual Web Part project. Once you ve set it up, select the project, right-click, and choose Add > New Item. In the resulting dialog box, select the SharePoint 2010 category in the left pane and add a user control. Give the control the name RequiredNumberField. Visual Studio will add a new SharePoint mapped folder called ControlTemplates, which corresponds to the {SharePoint Root} and TEMPLATE\CONTROLTEMPLATES folder. In this folder, Visual Studio also creates a subfolder with the name of your project and adds the user control to this subfolder. Your Solution Explorer should look like the one shown in figure 4.6.
Figure 4.6 The Visual Studio Solution Explorer can be used to add the SharePoint mapped folders in order to include the files that will be deployed to the SharePoint root.
Copyright © OnBarcode.com . All rights reserved.