"""
Namespace that defines fields common to all blocks used in the LMS
"""
#from django.utils.translation import ugettext_noop as _
from lazy import lazy
from xblock.fields import Boolean, Scope, String, XBlockMixin, Dict
from xblock.validation import ValidationMessage
from xmodule.modulestore.inheritance import UserPartitionList
from xmodule.partitions.partitions import NoSuchUserPartitionError, NoSuchUserPartitionGroupError
# Please do not remove, this is a workaround for Django 1.8.
# more information can be found here: https://openedx.atlassian.net/browse/PLAT-902
_ = lambda text: text
class GroupAccessDict(Dict):
"""Special Dict class for serializing the group_access field"""
def from_json(self, access_dict):
if access_dict is not None:
return {int(k): access_dict[k] for k in access_dict}
def to_json(self, access_dict):
if access_dict is not None:
return {unicode(k): access_dict[k] for k in access_dict}
class LmsBlockMixin(XBlockMixin):
"""
Mixin that defines fields common to all blocks used in the LMS
"""
hide_from_toc = Boolean(
help=_("Whether to display this module in the table of contents"),
default=False,
scope=Scope.settings
)
format = String(
# Translators: "TOC" stands for "Table of Contents"
help=_("What format this module is in (used for deciding which "
"grader to apply, and what to show in the TOC)"),
scope=Scope.settings,
)
chrome = String(
display_name=_("Course Chrome"),
# Translators: DO NOT translate the words in quotes here, they are
# specific words for the acceptable values.
help=_("Enter the chrome, or navigation tools, to use for the XBlock in the LMS. Valid values are: \n"
"\"chromeless\" -- to not use tabs or the accordion; \n"
"\"tabs\" -- to use tabs only; \n"
"\"accordion\" -- to use the accordion only; or \n"
"\"tabs,accordion\" -- to use tabs and the accordion."),
scope=Scope.settings,
default=None,
)
default_tab = String(
display_name=_("Default Tab"),
help=_("Enter the tab that is selected in the XBlock. If not set, the Course tab is selected."),
scope=Scope.settings,
default=None,
)
source_file = String(
display_name=_("LaTeX Source File Name"),
help=_("Enter the source file name for LaTeX."),
scope=Scope.settings,
deprecated=True
)
visible_to_staff_only = Boolean(
help=_("If true, can be seen only by course staff, regardless of start date."),
default=False,
scope=Scope.settings,
)
group_access = GroupAccessDict(
help=_(
"A dictionary that maps which groups can be shown this block. The keys "
"are group configuration ids and the values are a list of group IDs. "
"If there is no key for a group configuration or if the set of group IDs "
"is empty then the block is considered visible to all. Note that this "
"field is ignored if the block is visible_to_staff_only."
),
default={},
scope=Scope.settings,
)
@lazy
def merged_group_access(self):
"""
This computes access to a block's group_access rules in the context of its position
within the courseware structure, in the form of a lazily-computed attribute.
Each block's group_access rule is merged recursively with its parent's, guaranteeing
that any rule in a parent block will be enforced on descendants, even if a descendant
also defined its own access rules. The return value is always a dict, with the same
structure as that of the group_access field.
When merging access rules results in a case where all groups are denied access in a
user partition (which effectively denies access to that block for all students),
the special value False will be returned for that user partition key.
"""
parent = self.get_parent()
if not parent:
return self.group_access or {}
merged_access = parent.merged_group_access.copy()
if self.group_access is not None:
for partition_id, group_ids in self.group_access.items():
if group_ids: # skip if the "local" group_access for this partition is None or empty.
if partition_id in merged_access:
if merged_access[partition_id] is False:
# special case - means somewhere up the hierarchy, merged access rules have eliminated
# all group_ids from this partition, so there's no possible intersection.
continue
# otherwise, if the parent defines group access rules for this partition,
# intersect with the local ones.
merged_access[partition_id] = list(
set(merged_access[partition_id]).intersection(group_ids)
) or False
else:
# add the group access rules for this partition to the merged set of rules.
merged_access[partition_id] = group_ids
return merged_access
# Specified here so we can see what the value set at the course-level is.
user_partitions = UserPartitionList(
help=_("The list of group configurations for partitioning students in content experiments."),
default=[],
scope=Scope.settings
)
def _get_user_partition(self, user_partition_id):
"""
Returns the user partition with the specified id. Raises
`NoSuchUserPartitionError` if the lookup fails.
"""
for user_partition in self.user_partitions:
if user_partition.id == user_partition_id:
return user_partition
raise NoSuchUserPartitionError("could not find a UserPartition with ID [{}]".format(user_partition_id))
def validate(self):
"""
Validates the state of this xblock instance.
"""
_ = self.runtime.service(self, "i18n").ugettext
validation = super(LmsBlockMixin, self).validate()
has_invalid_user_partitions = False
has_invalid_groups = False
for user_partition_id, group_ids in self.group_access.iteritems():
try:
user_partition = self._get_user_partition(user_partition_id)
except NoSuchUserPartitionError:
has_invalid_user_partitions = True
else:
# Skip the validation check if the partition has been disabled
if user_partition.active:
for group_id in group_ids:
try:
user_partition.get_group(group_id)
except NoSuchUserPartitionGroupError:
has_invalid_groups = True
if has_invalid_user_partitions:
validation.add(
ValidationMessage(
ValidationMessage.ERROR,
_(u"This component refers to deleted or invalid content group configurations.")
)
)
if has_invalid_groups:
validation.add(
ValidationMessage(
ValidationMessage.ERROR,
_(u"This component refers to deleted or invalid content groups.")
)
)
return validation