Friday, September 16, 2016

Understanding options for Html.ValidationSummary in ASP.NET MVC Views

If you are confused about how the @Html.ValidationSummary Razor Html Helper works, you are certainly not the only one!

You can read about the various options for the ValidationSummary control here:

There are 3 MAJOR uses of @Html.ValidationSummary as follows:

  • @Html.ValidationSummary()
  • @Html.ValidationSummary(true)
  • @Html.ValidationSummary(false)


No parameters for the ValidationSummary control is the equivalent of passing false as a parameter.  That is, the ValidationSummary control will display ALL Model errors including ModelState-level errors.


For the true parameter, you can see the definition directly from Visual Studio Intellisense:

This causes the ValidationSummary to ONLY display Model errors and exclude any ModelState-level errors.  Therefore, if you use some code in your MVC Controller such as ModelState.AddModelError("", "some error"); will not be added to the ValidationSummary control for display in your Razor view.


As with the no parameter version of the ValidationSummary Razor HTML Helper, the ValidationSummary control will display ALL Model errors including ModelState-level errors.

That is all there is to understanding how to use the ValidationSummary Html Helper in your ASP.NET MVC Web Applications!!

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