title: How to pass field attribute value to Django form field error message
body: <p>I want to change form validation error message <em>"This field is required"</em> to include field's label, e.g. <em>"Name field is required"</em>. Does Django provide a simple way to refer to field attributes in error messages?</p>
  
  <pre><code>errors = {
      'required': _('{label} field is required')
  }
  
  class MyForm(forms.Form):
      name = forms.CharField(label=_('Name'), error_messages=errors, max_length=80)
      age = forms.IntegerField(label=_('Age'), error_messages=errors)
  </code></pre>
  
  <p>I know I can override form's <code>__init__</code> method to construct error messages as I want, but I would like a cleaner way.</p>