title: How to change vue/vuetify text field color conditionally
body: <p>I'd like to conditionally apply a text color class in a text field.  The class I want is <code>red--text</code>, like this:</p>
  
  <pre><code>:class="{ red--text: myModel.someBool }"
  </code></pre>
  
  <p>...but that results in a parse error. The problem is related to the class name, I think, because this works:</p>
  
  <pre><code>&lt;v-text-field
    v-model="myModel" label="My Text"
    :class="{ red: myModel.someBool }"
  &gt;&lt;/v-text-field&gt;
  </code></pre>
  
  <p>...but I want to color the text, not the whole field.</p>
  
  <p>Enclosing the desired class name in quotes <code>'red--text'</code> prevents the parse error, but has no effect on the color.</p>
  
  <p>Is there a way to get what I want?</p>