def invalidate_certificate(request, generated_certificate, certificate_invalidation_data):
 if (len(CertificateInvalidation.get_certificate_invalidations(generated_certificate.course_id, generated_certificate.user)) > 0):
  raise ValueError(_('Certificate of {user} has already been invalidated. Please check your spelling and retry.').format(user=generated_certificate.user.username))
 if (not generated_certificate.is_valid()):
  raise ValueError(_('Certificate for student {user} is already invalid, kindly verify that certificate was generated for this student and then proceed.').format(user=generated_certificate.user.username))
 (certificate_invalidation, __) = CertificateInvalidation.objects.update_or_create(generated_certificate=generated_certificate, defaults={'invalidated_by': request.user, 'notes': certificate_invalidation_data.get('notes', ''), 'active': True})
 generated_certificate.invalidate()
 return {'id': certificate_invalidation.id, 'user': certificate_invalidation.generated_certificate.user.username, 'invalidated_by': certificate_invalidation.invalidated_by.username, 'created': certificate_invalidation.created.strftime('%B %d, %Y'), 'notes': certificate_invalidation.notes}

def invalidate_certificate ( request , generated_certificate , certificate_invalidation_data ) : if ( len ( CertificateInvalidation . get_certificate_invalidations ( generated_certificate . course_id , generated_certificate . user ) ) > 0 ) : raise ValueError ( _ ( 'Certificate of {user} has already been invalidated. Please check your spelling and retry.' ) . format ( user = generated_certificate . user . username ) ) if ( not generated_certificate . is_valid ( ) ) : raise ValueError ( _ ( 'Certificate for student {user} is already invalid, kindly verify that certificate was generated for this student and then proceed.' ) . format ( user = generated_certificate . user . username ) ) ( certificate_invalidation , __ ) = CertificateInvalidation . objects . update_or_create ( generated_certificate = generated_certificate , defaults = { 'invalidated_by' : request . user , 'notes' : certificate_invalidation_data . get ( 'notes' , '' ) , 'active' : True } ) generated_certificate . invalidate ( ) return { 'id' : certificate_invalidation . id , 'user' : certificate_invalidation . generated_certificate . user . username , 'invalidated_by' : certificate_invalidation . invalidated_by . username , 'created' : certificate_invalidation . created . strftime ( '%B %d, %Y' ) , 'notes' : certificate_invalidation . notes }
invalidate given generatedcertificate and add certificateinvalidation record for future reference or re-validation .