title: how to show a django ModelForm field as uneditable
body: <p>taking my initial lessons with <code>django ModelForm</code> ,I wanted to give the user ,ability to edit an entry in a blog.The <code>BlogEntry</code> has a <code>date,postedTime, title and content</code>.I want to show the user an editform which shows all these fields,but with only <code>title and content as editable</code>. The <code>date and postedTime should be shown as uneditable</code>.</p>
  
  <pre><code>class BlogEntry(models.Model):
     title = models.CharField(unique=True,max_length=50)
     description = models.TextField(blank=True)
     date = models.DateField(default=datetime.date.today)
     postedTime = models.TimeField(null=True)
  
  ...
  </code></pre>
  
  <p>For adding an entry ,I use a ModelForm in the normal way..</p>
  
  <pre><code>class BlogEntryAddForm(ModelForm):
      class Meta:
          model = BlogEntry
  ...
  </code></pre>
  
  <p>But how do I create the edit form?I want it to <code>show the date,postedTime as uneditable</code> (but still show them on the form) and let the user edit the <code>title and description</code>.</p>
  
  <p>if I use,<code>exclude in class Meta</code> for date and postedTime,that will cause them not to appear on the form.So,how can I show them as uneditable?</p>
  
  <pre><code>class BlogEntryEditForm(ModelForm):
      class Meta:
          model = BlogEntry
          ...?...
  </code></pre>