title: How to make validation summary list all errors at once?
body: <p>In our .cshtml file we use:</p>
  <pre><code>@Html.ValidationSummary(false, &quot;&quot;, new { @class = &quot;text-danger&quot; })
  </code></pre>
  <p>In the class in which we define the rows that can be edited, we have a custom method:</p>
  <pre><code>public IEnumerable&lt;ValidationResult&gt; Validate(ValidationContext validationContext)
  {
      if (a &lt; b)
      {
          yield return new ValidationResult(&quot;a must be greater than b.&quot;);
      }
  }
  </code></pre>
  <p>Now when we run this and make several mistakes, first only the errors are displayed that involve some non-entering of values into required fields. Only after fixing these errors will the errors issued by our Validate method be displayed. We would however like to display all errors at once. How can we do that?</p>