title: Django: Does not raise error if CharField and TextField are not provided
body: <p>In Django model fields by default <code>blank=False</code> and <code>null=False</code></p>
  
  <pre><code>class Test(models.Model):
      name = models.CharField()
  </code></pre>
  
  <p>Now i try to save Test without supplying name</p>
  
  <pre><code>Test.objects.create(pk=1)
  </code></pre>
  
  <p>Now i am expecting it should raise an exception <code>"null value in column "name" violates not-null constraint"</code> saying that name is required. Whereas for other fields it will raise an exception that we have to provide the value</p>
  
  <p>So is it some default behaviour for CharField and TextField that will allow to store empty string irrespective of blank and null, if we try to save a model directly without any forms.</p>