title: Retrieving IDataErrorInfo string result in viewmodel
body: <p>I am after how I could get the string from the IDataErrorInfo.this[string propertyName] method from my ViewModel. </p>
  
  <p>basically, I have created a new property inside the model so I could validate each row in the model collection, and on my vaildation check, I will say if its valid or not and if not, it will disable the command in my viewmodel </p>
  
  <p>Model</p>
  
  <pre><code>   string IDataErrorInfo.this[string propertyName]
      {
          get
          {
              // Vaildation logic
  
              if (result != string.Empty)
              {
                  IsValid = false;
              }
              else
              {
                  IsValid = true;
              }
  
              return result;
          }
  </code></pre>
  
  <p>ViewModel</p>
  
  <pre><code>    public bool CanSave
      {
          get
          {
              if (m_ProductVersion != null &amp;&amp; m_ProductVersion.ProductItems != null)
              {
                  foreach (ProductItem item in m_ProductVersion.ProductItems)
                  {
                      // I dont want to use isValid any more
                      if (!item.IsValid)
                          return false;
                  }
              }
  
              return true;
          }
      }
  </code></pre>
  
  <p>But I would like to get rid of the isValid Property if I can and use the result from the IDataErrorInfo inside the viewmodel.</p>
  
  <p>Can this be done?  </p>
  
  <p>Thanks   </p>