# -*- coding: utf-8 -*-
"""
Certificates are created for a student and an offering of a course.
When a certificate is generated, a unique ID is generated so that
the certificate can be verified later. The ID is a UUID4, so that
it can't be easily guessed and so that it is unique.
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.
State diagram:
[deleted,error,unavailable] [error,downloadable]
+ + +
| | |
| | |
add_cert regen_cert del_cert
| | |
v v v
[generating] [regenerating] [deleting]
+ + +
| | |
certificate certificate certificate
created removed,created deleted
+----------------+-------------+------->[error]
| | |
| | |
v v v
[downloadable] [downloadable] [deleted]
Eligibility:
Students are eligible for a certificate if they pass the course
with the following exceptions:
If the student has allow_certificate set to False in the student profile
he will never be issued a certificate.
If the user and course is present in the certificate whitelist table
then the student will be issued a certificate regardless of his grade,
unless he has allow_certificate set to False.
"""
from datetime import datetime
import json
import logging
import uuid
import os
from django.contrib.auth.models import User
from django.core.exceptions import ValidationError
from django.db import models, transaction
from django.db.models.signals import post_save
from django.dispatch import receiver
from django.conf import settings
from django.utils.translation import ugettext_lazy as _
from django_extensions.db.fields.json import JSONField
from model_utils import Choices
from model_utils.models import TimeStampedModel
from xmodule.modulestore.django import modulestore
from config_models.models import ConfigurationModel
from xmodule_django.models import CourseKeyField, NoneToEmptyManager
from util.milestones_helpers import fulfill_course_milestone
from course_modes.models import CourseMode
LOGGER = logging.getLogger(__name__)
class CertificateStatuses(object):
deleted = 'deleted'
deleting = 'deleting'
downloadable = 'downloadable'
error = 'error'
generating = 'generating'
notpassing = 'notpassing'
regenerating = 'regenerating'
restricted = 'restricted'
unavailable = 'unavailable'
class CertificateSocialNetworks(object):
"""
Enum for certificate social networks
"""
linkedin = 'LinkedIn'
facebook = 'Facebook'
twitter = 'Twitter'
class CertificateWhitelist(models.Model):
"""
Tracks students who are whitelisted, all users
in this table will always qualify for a certificate
regardless of their grade unless they are on the
embargoed country restriction list
(allow_certificate set to False in userprofile).
"""
objects = NoneToEmptyManager()
user = models.ForeignKey(User)
course_id = CourseKeyField(max_length=255, blank=True, default=None)
whitelist = models.BooleanField(default=0)
class GeneratedCertificate(models.Model):
MODES = Choices('verified', 'honor', 'audit')
VERIFIED_CERTS_MODES = [CourseMode.VERIFIED, CourseMode.CREDIT_MODE]
user = models.ForeignKey(User)
course_id = CourseKeyField(max_length=255, blank=True, default=None)
verify_uuid = models.CharField(max_length=32, blank=True, default='')
download_uuid = models.CharField(max_length=32, blank=True, default='')
download_url = models.CharField(max_length=128, blank=True, default='')
grade = models.CharField(max_length=5, blank=True, default='')
key = models.CharField(max_length=32, blank=True, default='')
distinction = models.BooleanField(default=False)
status = models.CharField(max_length=32, default='unavailable')
mode = models.CharField(max_length=32, choices=MODES, default=MODES.honor)
name = models.CharField(blank=True, max_length=255)
created_date = models.DateTimeField(
auto_now_add=True, default=datetime.now)
modified_date = models.DateTimeField(
auto_now=True, default=datetime.now)
error_reason = models.CharField(max_length=512, blank=True, default='')
class Meta(object): # pylint: disable=missing-docstring
unique_together = (('user', 'course_id'),)
@classmethod
def certificate_for_student(cls, student, course_id):
"""
This returns the certificate for a student for a particular course
or None if no such certificate exits.
"""
try:
return cls.objects.get(user=student, course_id=course_id)
except cls.DoesNotExist:
pass
return None
@receiver(post_save, sender=GeneratedCertificate)
def handle_post_cert_generated(sender, instance, **kwargs): # pylint: disable=no-self-argument, unused-argument
"""
Handles post_save signal of GeneratedCertificate, and mark user collected
course milestone entry if user has passed the course.
User is assumed to have passed the course if certificate status is either 'generating' or 'downloadable'.
"""
allowed_cert_states = [CertificateStatuses.generating, CertificateStatuses.downloadable]
if settings.FEATURES.get('ENABLE_PREREQUISITE_COURSES') and instance.status in allowed_cert_states:
fulfill_course_milestone(instance.course_id, instance.user)
def certificate_status_for_student(student, course_id):
'''
This returns a dictionary with a key for status, and other information.
The status is one of the following:
unavailable - No entry for this student--if they are actually in
the course, they probably have not been graded for
certificate generation yet.
generating - A request has been made to generate a certificate,
but it has not been generated yet.
regenerating - A request has been made to regenerate a certificate,
but it has not been generated yet.
deleting - A request has been made to delete a certificate.
deleted - The certificate has been deleted.
downloadable - The certificate is available for download.
notpassing - The student was graded but is not passing
restricted - The student is on the restricted embargo list and
should not be issued a certificate. This will
be set if allow_certificate is set to False in
the userprofile table
If the status is "downloadable", the dictionary also contains
"download_url".
If the student has been graded, the dictionary also contains their
grade for the course with the key "grade".
'''
try:
generated_certificate = GeneratedCertificate.objects.get(
user=student, course_id=course_id)
d = {'status': generated_certificate.status,
'mode': generated_certificate.mode}
if generated_certificate.grade:
d['grade'] = generated_certificate.grade
if generated_certificate.status == CertificateStatuses.downloadable:
d['download_url'] = generated_certificate.download_url
return d
except GeneratedCertificate.DoesNotExist:
pass
return {'status': CertificateStatuses.unavailable, 'mode': GeneratedCertificate.MODES.honor}
def certificate_info_for_user(user, course_id, grade, user_is_whitelisted=None):
"""
Returns the certificate info for a user for grade report.
"""
if user_is_whitelisted is None:
user_is_whitelisted = CertificateWhitelist.objects.filter(
user=user, course_id=course_id, whitelist=True
).exists()
eligible_for_certificate = (user_is_whitelisted or grade is not None) and user.profile.allow_certificate
if eligible_for_certificate:
user_is_eligible = 'Y'
certificate_status = certificate_status_for_student(user, course_id)
certificate_generated = certificate_status['status'] == CertificateStatuses.downloadable
certificate_is_delivered = 'Y' if certificate_generated else 'N'
certificate_type = certificate_status['mode'] if certificate_generated else 'N/A'
else:
user_is_eligible = 'N'
certificate_is_delivered = 'N'
certificate_type = 'N/A'
return [user_is_eligible, certificate_is_delivered, certificate_type]
class ExampleCertificateSet(TimeStampedModel):
"""A set of example certificates.
Example certificates are used to verify that certificate
generation is working for a particular course.
A particular course may have several kinds of certificates
(e.g. honor and verified), in which case we generate
multiple example certificates for the course.
"""
course_key = CourseKeyField(max_length=255, db_index=True)
class Meta(object): # pylint: disable=missing-docstring
get_latest_by = 'created'
@classmethod
@transaction.commit_on_success
def create_example_set(cls, course_key):
"""Create a set of example certificates for a course.
Arguments:
course_key (CourseKey)
Returns:
ExampleCertificateSet
"""
cert_set = cls.objects.create(course_key=course_key)
ExampleCertificate.objects.bulk_create([
ExampleCertificate(
example_cert_set=cert_set,
description=mode.slug,
template=cls._template_for_mode(mode.slug, course_key)
)
for mode in CourseMode.modes_for_course(course_key)
])
return cert_set
@classmethod
def latest_status(cls, course_key):
"""Summarize the latest status of example certificates for a course.
Arguments:
course_key (CourseKey)
Returns:
list: List of status dictionaries. If no example certificates
have been started yet, returns None.
"""
try:
latest = cls.objects.filter(course_key=course_key).latest()
except cls.DoesNotExist:
return None
queryset = ExampleCertificate.objects.filter(example_cert_set=latest).order_by('-created')
return [cert.status_dict for cert in queryset]
def __iter__(self):
"""Iterate through example certificates in the set.
Yields:
ExampleCertificate
"""
queryset = (ExampleCertificate.objects).select_related('example_cert_set').filter(example_cert_set=self)
for cert in queryset:
yield cert
@staticmethod
def _template_for_mode(mode_slug, course_key):
"""Calculate the template PDF based on the course mode. """
return (
u"certificate-template-{key.org}-{key.course}-verified.pdf".format(key=course_key)
if mode_slug == 'verified'
else u"certificate-template-{key.org}-{key.course}.pdf".format(key=course_key)
)
def _make_uuid():
"""Return a 32-character UUID. """
return uuid.uuid4().hex
class ExampleCertificate(TimeStampedModel):
"""Example certificate.
Example certificates are used to verify that certificate
generation is working for a particular course.
An example certificate is similar to an ordinary certificate,
except that:
1) Example certificates are not associated with a particular user,
and are never displayed to students.
2) We store the "inputs" for generating the example certificate
to make it easier to debug when certificate generation fails.
3) We use dummy values.
"""
# Statuses
STATUS_STARTED = 'started'
STATUS_SUCCESS = 'success'
STATUS_ERROR = 'error'
# Dummy full name for the generated certificate
EXAMPLE_FULL_NAME = u'John Doë'
example_cert_set = models.ForeignKey(ExampleCertificateSet)
description = models.CharField(
max_length=255,
help_text=_(
u"A human-readable description of the example certificate. "
u"For example, 'verified' or 'honor' to differentiate between "
u"two types of certificates."
)
)
# Inputs to certificate generation
# We store this for auditing purposes if certificate
# generation fails.
uuid = models.CharField(
max_length=255,
default=_make_uuid,
db_index=True,
unique=True,
help_text=_(
u"A unique identifier for the example certificate. "
u"This is used when we receive a response from the queue "
u"to determine which example certificate was processed."
)
)
access_key = models.CharField(
max_length=255,
default=_make_uuid,
db_index=True,
help_text=_(
u"An access key for the example certificate. "
u"This is used when we receive a response from the queue "
u"to validate that the sender is the same entity we asked "
u"to generate the certificate."
)
)
full_name = models.CharField(
max_length=255,
default=EXAMPLE_FULL_NAME,
help_text=_(u"The full name that will appear on the certificate.")
)
template = models.CharField(
max_length=255,
help_text=_(u"The template file to use when generating the certificate.")
)
# Outputs from certificate generation
status = models.CharField(
max_length=255,
default=STATUS_STARTED,
choices=(
(STATUS_STARTED, 'Started'),
(STATUS_SUCCESS, 'Success'),
(STATUS_ERROR, 'Error')
),
help_text=_(u"The status of the example certificate.")
)
error_reason = models.TextField(
null=True,
default=None,
help_text=_(u"The reason an error occurred during certificate generation.")
)
download_url = models.CharField(
max_length=255,
null=True,
default=None,
help_text=_(u"The download URL for the generated certificate.")
)
def update_status(self, status, error_reason=None, download_url=None):
"""Update the status of the example certificate.
This will usually be called either:
1) When an error occurs adding the certificate to the queue.
2) When we receieve a response from the queue (either error or success).
If an error occurs, we store the error message;
if certificate generation is successful, we store the URL
for the generated certificate.
Arguments:
status (str): Either `STATUS_SUCCESS` or `STATUS_ERROR`
Keyword Arguments:
error_reason (unicode): A description of the error that occurred.
download_url (unicode): The URL for the generated certificate.
Raises:
ValueError: The status is not a valid value.
"""
if status not in [self.STATUS_SUCCESS, self.STATUS_ERROR]:
msg = u"Invalid status: must be either '{success}' or '{error}'.".format(
success=self.STATUS_SUCCESS,
error=self.STATUS_ERROR
)
raise ValueError(msg)
self.status = status
if status == self.STATUS_ERROR and error_reason:
self.error_reason = error_reason
if status == self.STATUS_SUCCESS and download_url:
self.download_url = download_url
self.save()
@property
def status_dict(self):
"""Summarize the status of the example certificate.
Returns:
dict
"""
result = {
'description': self.description,
'status': self.status,
}
if self.error_reason:
result['error_reason'] = self.error_reason
if self.download_url:
result['download_url'] = self.download_url
return result
@property
def course_key(self):
"""The course key associated with the example certificate. """
return self.example_cert_set.course_key
class CertificateGenerationCourseSetting(TimeStampedModel):
"""Enable or disable certificate generation for a particular course.
This controls whether students are allowed to "self-generate"
certificates for a course. It does NOT prevent us from
batch-generating certificates for a course using management
commands.
In general, we should only enable self-generated certificates
for a course once we successfully generate example certificates
for the course. This is enforced in the UI layer, but
not in the data layer.
"""
course_key = CourseKeyField(max_length=255, db_index=True)
enabled = models.BooleanField(default=False)
class Meta(object): # pylint: disable=missing-docstring
get_latest_by = 'created'
@classmethod
def is_enabled_for_course(cls, course_key):
"""Check whether self-generated certificates are enabled for a course.
Arguments:
course_key (CourseKey): The identifier for the course.
Returns:
boolean
"""
try:
latest = cls.objects.filter(course_key=course_key).latest()
except cls.DoesNotExist:
return False
else:
return latest.enabled
@classmethod
def set_enabled_for_course(cls, course_key, is_enabled):
"""Enable or disable self-generated certificates for a course.
Arguments:
course_key (CourseKey): The identifier for the course.
is_enabled (boolean): Whether to enable or disable self-generated certificates.
"""
CertificateGenerationCourseSetting.objects.create(
course_key=course_key,
enabled=is_enabled
)
class CertificateGenerationConfiguration(ConfigurationModel):
"""Configure certificate generation.
Enable or disable the self-generated certificates feature.
When this flag is disabled, the "generate certificate" button
will be hidden on the progress page.
When the feature is enabled, the "generate certificate" button
will appear for courses that have enabled self-generated
certificates.
"""
pass
class CertificateHtmlViewConfiguration(ConfigurationModel):
"""
Static values for certificate HTML view context parameters.
Default values will be applied across all certificate types (course modes)
Matching 'mode' overrides will be used instead of defaults, where applicable
Example configuration :
{
"default": {
"url": "http://www.edx.org",
"logo_src": "http://www.edx.org/static/images/logo.png"
},
"honor": {
"logo_src": "http://www.edx.org/static/images/honor-logo.png"
}
}
"""
configuration = models.TextField(
help_text="Certificate HTML View Parameters (JSON)"
)
def clean(self):
"""
Ensures configuration field contains valid JSON.
"""
try:
json.loads(self.configuration)
except ValueError:
raise ValidationError('Must be valid JSON string.')
@classmethod
def get_config(cls):
"""
Retrieves the configuration field value from the database
"""
instance = cls.current()
json_data = json.loads(instance.configuration) if instance.enabled else {}
return json_data
class BadgeAssertion(models.Model):
"""
Tracks badges on our side of the badge baking transaction
"""
user = models.ForeignKey(User)
course_id = CourseKeyField(max_length=255, blank=True, default=None)
# Mode a badge was awarded for.
mode = models.CharField(max_length=100)
data = JSONField()
@property
def image_url(self):
"""
Get the image for this assertion.
"""
return self.data['image']
@property
def assertion_url(self):
"""
Get the public URL for the assertion.
"""
return self.data['json']['id']
class Meta(object):
"""
Meta information for Django's construction of the model.
"""
unique_together = (('course_id', 'user', 'mode'),)
def validate_badge_image(image):
"""
Validates that a particular image is small enough, of the right type, and square to be a badge.
"""
if image.width != image.height:
raise ValidationError(_(u"The badge image must be square."))
if not image.size < (250 * 1024):
raise ValidationError(_(u"The badge image file size must be less than 250KB."))
class BadgeImageConfiguration(models.Model):
"""
Contains the configuration for badges for a specific mode. The mode
"""
mode = models.CharField(
max_length=125,
help_text=_(u'The course mode for this badge image. For example, "verified" or "honor".'),
unique=True,
)
icon = models.ImageField(
# Actual max is 256KB, but need overhead for badge baking. This should be more than enough.
help_text=_(
u"Badge images must be square PNG files. The file size should be under 250KB."
),
upload_to='badges',
validators=[validate_badge_image]
)
default = models.BooleanField(
help_text=_(
u"Set this value to True if you want this image to be the default image for any course modes "
u"that do not have a specified badge image. You can have only one default image."
)
)
def clean(self):
"""
Make sure there's not more than one default.
"""
# pylint: disable=no-member
if self.default and BadgeImageConfiguration.objects.filter(default=True).exclude(id=self.id):
raise ValidationError(_(u"There can be only one default image."))
@classmethod
def image_for_mode(cls, mode):
"""
Get the image for a particular mode.
"""
try:
return cls.objects.get(mode=mode).icon
except cls.DoesNotExist:
# Fall back to default, if there is one.
return cls.objects.get(default=True).icon
class CertificateTemplate(TimeStampedModel):
"""A set of custom web certificate templates.
Web certificate templates are Django web templates
to replace PDF certificate.
A particular course may have several kinds of certificate templates
(e.g. honor and verified).
"""
name = models.CharField(
max_length=255,
help_text=_(u'Name of template.'),
)
description = models.CharField(
max_length=255,
null=True,
blank=True,
help_text=_(u'Description and/or admin notes.'),
)
template = models.TextField(
help_text=_(u'Django template HTML.'),
)
organization_id = models.IntegerField(
null=True,
blank=True,
db_index=True,
help_text=_(u'Organization of template.'),
)
course_key = CourseKeyField(
max_length=255,
null=True,
blank=True,
db_index=True,
)
mode = models.CharField(
max_length=125,
choices=GeneratedCertificate.MODES,
default=GeneratedCertificate.MODES.honor,
null=True,
blank=True,
help_text=_(u'The course mode for this template.'),
)
is_active = models.BooleanField(
help_text=_(u'On/Off switch.'),
default=False,
)
def __unicode__(self):
return u'%s' % (self.name, )
class Meta(object): # pylint: disable=missing-docstring
get_latest_by = 'created'
unique_together = (('organization_id', 'course_key', 'mode'),)
def template_assets_path(instance, filename):
"""
Delete the file if it already exist and returns the certificate template asset file path.
:param instance: CertificateTemplateAsset object
:param filename: file to upload
:return path: path of asset file e.g. certificate_template_assets/1/filename
"""
name = os.path.join('certificate_template_assets', str(instance.id), filename)
fullname = os.path.join(settings.MEDIA_ROOT, name)
if os.path.exists(fullname):
os.remove(fullname)
return name
class CertificateTemplateAsset(TimeStampedModel):
"""A set of assets to be used in custom web certificate templates.
This model stores assets used in custom web certificate templates
such as image, css files.
"""
description = models.CharField(
max_length=255,
null=True,
blank=True,
help_text=_(u'Description of the asset.'),
)
asset = models.FileField(
max_length=255,
upload_to=template_assets_path,
help_text=_(u'Asset file. It could be an image or css file.'),
)
def save(self, *args, **kwargs):
"""save the certificate template asset """
if self.pk is None:
asset_image = self.asset
self.asset = None
super(CertificateTemplateAsset, self).save(*args, **kwargs)
self.asset = asset_image
super(CertificateTemplateAsset, self).save(*args, **kwargs)
def __unicode__(self):
return u'%s' % (self.asset.url, ) # pylint: disable=no-member
class Meta(object): # pylint: disable=missing-docstring
get_latest_by = 'created'
@receiver(post_save, sender=GeneratedCertificate)
#pylint: disable=unused-argument
def create_badge(sender, instance, **kwargs):
"""
Standard signal hook to create badges when a certificate has been generated.
"""
if not settings.FEATURES.get('ENABLE_OPENBADGES', False):
return
if not modulestore().get_course(instance.course_id).issue_badges:
LOGGER.info("Course is not configured to issue badges.")
return
if BadgeAssertion.objects.filter(user=instance.user, course_id=instance.course_id):
LOGGER.info("Badge already exists for this user on this course.")
# Badge already exists. Skip.
return
# Don't bake a badge until the certificate is available. Prevents user-facing requests from being paused for this
# by making sure it only gets run on the callback during normal workflow.
if not instance.status == CertificateStatuses.downloadable:
return
from .badge_handler import BadgeHandler
handler = BadgeHandler(instance.course_id)
handler.award(instance.user)