How can I stop a broken webpart from killing the whole page?

Question

The title says it all, when there's a error in my webpart I can't load the whole page.

I'd like just to don't display the webpart and still see the rest of the page and not just get the error page. Can this be done without catching all errors?

Answer 1

You have two options:

1. Catch all errors in your web part and then log them to ULS, show in hidden div, ...
2. Develop you web part in a Sandboxed solution, then SharePoint will take care of protecting the rest of the page

To elaborate on the first. It can be implemented using this pattern:

• Add a string variable errorMessage

  string errorMessage;
  

• Write each overloaded "event" function to exit if previous error and catch any errors

  protected override void CreateChildControls()
  {
      try
      {
          if (errorMessage != null)
              return;
          // real code
      }
      catch (Exception ex)
      {
          // Log to ULS
          // ...
          // Set Error Message
          errorMessage = "Error in CreateChildControls";
      }
  }
  

• Override RenderContent to render error (and only error) if it occurred

  protected override void Render(HtmlTextWriter writer)
  {
      if (errorMessage == null)
      {
          try
          {
              var textWriter = new StringWriter();
              using (var tempWriter = new HtmlTextWriter(textWriter))
                  base.Render(tempWriter);
              writer.Write(textWriter.ToString());
          }
          catch (Exception ex)
          {
              // Log to ULS
              // ...
              // Set Error Message
              errorMessage = "Error in CreateChildControls";
          }
      }
      if (errorMessage != null)
      {
          writer.Write("<span class='error'>An unexpected Error occurred. Contact the fool who created this web part</span><div style='display:none;'>{0}</div>",
              HttpUtility.HtmlEncode(errorMessage));
      }
  }
  

Answer 2

If you want to just remove the Web Part (or disable them all) you can add

?contents=1

to your querystring, then you can manage your Web Parts