Updating the certificates model for automatic certificate generation

lms/djangoapps/certificates/models.py

-from django.conf import settings as settings
-
 from django.contrib.auth.models import User
 from django.db import models
 
@@ -14,131 +12,65 @@ we save these generated certificates (for later verification), we
 also record the UUID so that if we regenerate the certificate it
 will have the same UUID.
 
-If certificates are being generated on the fly, a GeneratedCertificate
-should be created with the user, certificate_id, and enabled set
-when a student requests a certificate. When the certificate has been
-generated, the download_url should be set.
+Certificates are generated in batches by a cron job, when a
+certificate is available for download the GeneratedCertificate
+table is updated with information that will be displayed
+on the course overview page.
 
-Certificates can also be pre-generated. In this case, the user,
-certificate_id, and download_url are all set before the user does
-anything. When the user requests the certificate, only enabled
-needs to be set to true.
 
 '''
 
 
 class GeneratedCertificate(models.Model):
-    user = models.ForeignKey(User, db_index=True)
-    # This is the name at the time of request
-    name = models.CharField(blank=True, max_length=255)
-
-    certificate_id = models.CharField(max_length=32, null=True, default=None)
-    graded_certificate_id = models.CharField(max_length=32, null=True, default=None)
-
-    download_url = models.CharField(max_length=128, null=True)
-    graded_download_url = models.CharField(max_length=128, null=True)
-
-    grade = models.CharField(max_length=5, null=True)
-
-    # enabled should only be true if the student has earned a grade in the course
-    # The student must have a grade and request a certificate for enabled to be True
-    enabled = models.BooleanField(default=False)
-
-
-class RevokedCertificate(models.Model):
-    """
-    This model is for when a GeneratedCertificate must be regenerated. This model
-    contains all the same fields, to store a record of what the GeneratedCertificate
-    was before it was revoked (at which time all of it's information can change when
-    it is regenerated).
-
-    GeneratedCertificate may be deleted once they are revoked, and then created again.
-    For this reason, the only link between a GeneratedCertificate and RevokedCertificate
-    is that they share the same user.
-    """
-    ####-------------------New Fields--------------------####
-    explanation = models.TextField(blank=True)
+    user = models.ForeignKey(User)
+    course_id = models.CharField(max_length=255)
+    certificate_id = models.CharField(max_length=32)
+    graded_certificate_id = models.CharField(max_length=32)
 
-    ####---------Fields from GeneratedCertificate---------####
-    user = models.ForeignKey(User, db_index=True)
-    # This is the name at the time of request
-    name = models.CharField(blank=True, max_length=255)
-
-    certificate_id = models.CharField(max_length=32, null=True, default=None)
-    graded_certificate_id = models.CharField(max_length=32, null=True, default=None)
-
-    download_url = models.CharField(max_length=128, null=True)
-    graded_download_url = models.CharField(max_length=128, null=True)
-
-    grade = models.CharField(max_length=5, null=True)
+    download_url = models.CharField(max_length=128)
+    graded_download_url = models.CharField(max_length=128)
+    grade = models.CharField(max_length=5)
 
+    # enabled should only be true if the student has earned a passing grade
+    # in the course.
     enabled = models.BooleanField(default=False)
 
 
-def revoke_certificate(certificate, explanation):
-    """
-    This method takes a GeneratedCertificate. It records its information from the certificate
-    into a RevokedCertificate, and then marks the certificate as needing regenerating.
-    When the new certificiate is regenerated it will have new IDs and download URLS.
-
-    Once this method has been called, it is safe to delete the certificate, or modify the
-    certificate's name or grade until it has been generated again.
-    """
-    revoked = RevokedCertificate(user=certificate.user,
-                                    name=certificate.name,
-                                    certificate_id=certificate.certificate_id,
-                                    graded_certificate_id=certificate.graded_certificate_id,
-                                    download_url=certificate.download_url,
-                                    graded_download_url=certificate.graded_download_url,
-                                    grade=certificate.grade,
-                                    enabled=certificate.enabled)
-
-    revoked.explanation = explanation
-
-    certificate.certificate_id = None
-    certificate.graded_certificate_id = None
-    certificate.download_url = None
-    certificate.graded_download_url = None
-
-    certificate.save()
-    revoked.save()
-
-
-def certificate_state_for_student(student, grade):
+def certificate_state_for_student(student):
     '''
-    This returns a dictionary with a key for state, and other information. The state is one of the
-    following:
+    This returns a dictionary with a key for state, and other information.
+    The state is one of the following:
 
-    unavailable - A student is not eligible for a certificate.
-    requestable - A student is eligible to request a certificate
-    generating - A student has requested a certificate, but it is not generated yet.
-    downloadable - The certificate has been requested and is available for download.
+    unavailable  - A student is not eligible for a certificate.
+    generating   - A student has requested a certificate,
+                   but it is not generated yet.
+    downloadable - The certificate has been requested and is
+                   available for download.
 
-    If the state is "downloadable", the dictionary also contains "download_url" and "graded_download_url".
+    If the state is "downloadable", the dictionary also contains
+    "download_url" and "graded_download_url".
 
     '''
 
-    if grade:
-        #TODO: Remove the following after debugging
-        if settings.DEBUG_SURVEY:
-            return {'state': 'requestable'}
-
-        try:
-            generated_certificate = GeneratedCertificate.objects.get(user=student)
-            if generated_certificate.enabled:
-                if generated_certificate.download_url:
-                    return {'state': 'downloadable',
-                             'download_url': generated_certificate.download_url,
-                             'graded_download_url': generated_certificate.graded_download_url}
-                else:
-                    return {'state': 'generating'}
+    try:
+        generated_certificate = GeneratedCertificate.objects.get(
+                user=student)
+        if generated_certificate.enabled:
+            if generated_certificate.download_url:
+                return {
+                      'state': 'downloadable',
+                      'download_url':
+                        generated_certificate.download_url,
+                      'graded_download_url':
+                        generated_certificate.graded_download_url
+                       }
             else:
-                # If enabled=False, it may have been pre-generated but not yet requested
-                # Our output will be the same as if the GeneratedCertificate did not exist
-                pass
-        except GeneratedCertificate.DoesNotExist:
+                return {'state': 'generating'}
+        else:
+            # If enabled=False, there is no certificate available
+            # Our output will be the same as if the
+            # GeneratedCertificate did not exist
             pass
-        return {'state': 'requestable'}
-    else:
-        # No grade, no certificate. No exceptions
-        return {'state': 'unavailable'}
+    except GeneratedCertificate.DoesNotExist:
+        pass
+    return {'state': 'unavailable'}