Button download pdf sur django

Bonjour,
je tente de creer sur mon app django un bouton download pdf
mais j obtiens ceci comme error

AttributeError at /views.download_my_pdf
'str' object has no attribute 'read'


html

<a class="btn btn-primary" href="{% url 'download_pdf' %}" role="button">Download pdf</a>

views.py

def download_pdf(request):
    filename = 'faults.pdf'
    content = FileWrapper(filename)
    response = HttpResponse(content, content_type='application/pdf')
    response['Content-Length'] = os.path.getsize(filename)
    response['Content-Disposition'] = 'attachment; filename=%s' % 'faults.pdf'

    return response

qui peut m aider ? merci