title: Blazor get validation message for two properties
body: <p>I have a simple EditForm within a Blazor Server Side application. It has an bound property which changes another property which should also be validated by the form.</p>
  <p>The form contains the following section</p>
  <pre><code>&lt;div class=&quot;form-group col-md-6&quot;&gt;
      &lt;label for=&quot;inputRechnungsnummer&quot;&gt;Rechnungsnummer&lt;/label&gt;
      &lt;InputNumber @bind-Value=&quot;Input.Rechnungsnummer&quot; id=&quot;inputRechnungsnummer&quot; class=&quot;form-control&quot; /&gt;
      &lt;ValidationMessage For=&quot;() =&gt; Input.CustomerExists&quot; /&gt;
      &lt;ValidationMessage For=&quot;() =&gt; Input.Rechnungsnummer&quot; /&gt;
  &lt;/div&gt;
  </code></pre>
  <p>As you can see, I want to display two messages under this InputField.</p>
  <p>The bond field calls a method to find customer details.</p>
  <pre><code>public int Rechnungsnummer 
  { 
      get =&gt; _rechnungsnummer; 
      set
      {
          _rechnungsnummer = value;
          SearchKunde();
      }
  }
  </code></pre>
  <p>This method changed the value of my attribute</p>
  <pre><code>private void SearchKunde()
  {
  
      /* LOGIC */
      
      if(name != null)
      {
          Kundenname = name;
          CustomerExists = true;
      }
      else
      {
          Kundenname = &quot;&quot;;
          CustomerExists = false;
      }
  }
  </code></pre>
  <p>The second attribute is defined as:</p>
  <pre><code>[Required]
  [Range(typeof(bool), &quot;true&quot;, &quot;true&quot;, ErrorMessage = &quot;Bitte geben Sie eine gültige Rechnungsnummer ein&quot;)]
  public bool CustomerExists { get; set; }
  </code></pre>
  <p>However the validation message for CustomerExists won't be displayed. It is only shown once I try to submit my form.</p>
  <p>Does anybody know how I can achive to display the message after it's value has been changed?</p>