title: 'CountryPDF' object has no attribute 'data'
body: <p>Please help!What I am doing wrong?
  I have views.py to generate PDF.
  It is generate PDF success if context: 'Sometext'.It open me PDF link. But When I take django models.It output me : 'CountryPDF' object has no attribute 'data'</p>
  <pre><code>my views.py
  
  class CountryPDF(core.PDFView):
      template_name = 'application_pdf.html'
  
  
      def get_context_data(self, **kwargs):
          return {'data': self.data}
  
      def get_file_name(self, context):
          return 'test1.pdf'
  </code></pre>
  <p>So HTML file:
  application_pdf.html</p>
  <pre><code>{% for item in data %}
            &lt;td&gt;{{ item.name }}&lt;/td&gt;
            &lt;td&gt;{{ item.address }}&lt;/td&gt;
    {% endfor %}
  </code></pre>
  <p>url:</p>
  <pre><code>path('cabinet/&lt;int:pk&gt;/download-pdf/',
           views.CountryPDF.as_view(),
           name='country-download_pdf'),
  </code></pre>
  <p>What is the problem with context data? What I am doing wrong?</p>
  <pre><code>class PDFView(TemplateView):
      changed_fonts = False
  
      def get_context(self, **kwargs):
          raise NotImplementedError
  
      def get_file_name(self, context):
          raise NotImplementedError
  
      def get_context_data(self, **kwargs):
          ctx = super().get_context_data()
          ctx.update(self.get_context(**kwargs))
          return ctx
  </code></pre>