title: how to override default Django form validation error
body: <p>I try this but it doesn't work. default error message is shown only.please help............</p>
  
  <pre><code>from django import forms
  from SharedApps_Application.models import certificateDb
  from django.contrib.admin.widgets import AdminDateWidget
  from django.forms.fields import DateField
  
  my_default_errors = {
      'required': 'Application field is required',
  }
  
  class CertificateForm(forms.ModelForm):
  
      startdate = forms.DateField(widget = forms.SelectDateWidget(years=range(1995, 2100)))
      expiredate = forms.DateField(widget = forms.SelectDateWidget(years=range(1995, 2100)))
      application = forms.CharField(error_messages = my_default_errors)
      class Meta:
          model = certificateDb
          fields = ('application', 'startdate', 'expiredate', 'environment_type','File' )
  </code></pre>
  
  <blockquote>
    <p>screenshot</p>
  </blockquote>
  
  <p><a href="https://i.stack.imgur.com/6rXId.png" rel="nofollow noreferrer">[1]: https://i.stack.imgur.com/8zhM6.png</a></p>
  
  <blockquote>
    <p>update</p>
  </blockquote>
  
  <pre><code>from django import forms
  from SharedApps_Application.models import certificateDb
  from django.contrib.admin.widgets import AdminDateWidget
  from django.forms.fields import DateField
  class CertificateForm(forms.ModelForm):
  
      startdate = forms.DateField(widget = forms.SelectDateWidget(years=range(1995, 2100)))
      expiredate = forms.DateField(widget = forms.SelectDateWidget(years=range(1995, 2100)))
      application = forms.CharField()
      class Meta:
          model = certificateDb
          fields = ('application', 'startdate', 'expiredate', 'environment_type','File' )
  
          error_messages = {
              'application': {
                  'required': ("Application field is required"),
              },
              }
  </code></pre>