Asp net validating a checkboxlist control

Let us see how we can now perform validation directly on the client side, without a postback. As you observe, we override the On Pre Render method and use the Register Expando Attribute to assign the function name ‘Check If List Checked’ an attribute called ‘evaluationfunction’. This is done to make sure that if the users have turned off javascript on their browsers, then this call passes the control back to the page and allows the rendering to continue by calling base. If Java Script is enabled on your browsers, the validation errors are displayed before the form is posted back to the server.To perform client side validation, you would need to override On Pre Render and create the javascript function using a String Builder object and output it using Page. The javascript function(Check If List Checked) takes one parameter, the validator object and returns ‘true’ if Valid (item in both Radiobuttonlist or Check Box List is checked) and ‘false’ if Invalid (Item in either Radiobuttonlist or Check Box List is not selected). The entire source code of the application can be downloaded from here.However, there are a few shortcomings in these controls. NET provides the framework to create new validation controls.If you would like to create your own validation control, you can do so by deriving a new control from the Base Validator abstract class.Step 3: Our next step would be to create the custom validation control.But before that, let us quickly take an overview of what we are trying to achieve.As you will observe, the two controls are being validated by the same custom validation control that we are building.

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The Label is needed since the Check Box is hidden, and by associating the Label to the Check Box, the text will be clickable as well. (Found in the upper right corner of the letter you received) The "tabs" design pattern is just toggling on and off of areas, perfect for the checkbox hack.

Abstract: The Base Validator class defines the basic implementation needed for all Validation controls.

There are 6 Validation Controls included in the ASP. NET 3.5 framework, however with a few shortcomings.

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