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Using radCaptcha Via DotNetNuke Wrappers

23 Jun

When putting a form that is public facing we often need to add a captcha to help prevent bots from submitting our forms.  Historically there has been a control available within DotNetNuke that worked for this, but admittedly it didn't have the best customization nor was it the most "pretty" of them out there.  Ever since DotNetNuke has had the Telerik Controls a new option has been available yet its usage isn't the most widely documented.  In this post I'll show you how to use RadCaptcha in your own custom modules.

Why RadCaptcha?

Before I get too far into this I wanted to explain a bit about why you would use RadCaptcha over the existing DotNetNuke Captcha or another solution.  First for me is the ability to customize the output of the captcha.  If you look at the documentation from Telerik you will find options for audio, regeneration, and other items that help with the accessibility and usability of the captcha.  Additionally since this control has been wrapped with a DotNetNuke API it is easy for us to quickly integrate without needing to modify web.config files or distribute additional assemblies.

Implementing RadCaptcha

Implementation is actually quite simple for the basic steps.  First at the top of your control add the following Register Tag:

   1:  <%@ Register TagPrefix="dnn" Assembly="DotNetNuke.Web" 
   2:      Namespace="DotNetNuke.Web.UI.WebControls" %>

You might need to manually add a reference to DotNetNuke.Web.dll to your project if you get an error about the assembly not being found. From here you can add the Captcha to your form with basic configuration it might look like this:

   1:  <div class="dnnFormItem" >
   2:      <dnn:DnnCaptcha ID="ctlCaptcha" 
   3:           CaptchaWidth="300" EnableRefreshImage="True" 
   4:           CaptchaTextBoxLabel="Please type the characters you see 
   5:                 in the image into the text box above."
   6:           runat="server" 
   7:           ErrorMessage="The typed code must match the image, 
   8:                 please try again"/>
   9:  </div>

Now that you have this done you can simply check ctlCaptcha.IsValid in the code-behind and you are done!

But Wait There's More

That was quick and easy to do, but there is one piece of implementation that is still missing. And that is controlling the styles. Although I dropped this into a form styled with the default Form Pattern styles it doesn't look correct. The default rendering with the above options looks similar to the below.

bad captcha setup

As you can see the display is all jumbled, the inputs are on the left the label is on the right and things are going everywhere. Thankfully I've found a little snippet of CSS that will help. Add the following to your module.css.

   1:  .dnnForm .dnnFormItem .RadCaptcha 
   2:  { margin-left:32%; }
   3:   
   4:  .dnnForm .dnnFormItem .RadCaptcha LABEL 
   5:  { width: inherit; float: left; }

Conclusion

After including the above listed CSS you will see that the captcha now appears like the following:

Although my image is a bit distorted above you can see that they all line up neatly. I hope this helps some of you, as i know this was a "process" for me.

This article has been cross-posted to my blog at DotNetNuke.com.

tags: DNN, DNN Development, .NET 4.0, Quick Tips, .NET 4.5
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