538 lines
21 KiB
Python
538 lines
21 KiB
Python
from lxml import etree
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import pkg_resources
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import logging
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from xmodule.modulestore import Location
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from functools import partial
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log = logging.getLogger('mitx.' + __name__)
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def dummy_track(event_type, event):
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pass
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class ModuleMissingError(Exception):
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pass
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class Plugin(object):
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"""
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Base class for a system that uses entry_points to load plugins.
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Implementing classes are expected to have the following attributes:
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entry_point: The name of the entry point to load plugins from
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"""
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_plugin_cache = None
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@classmethod
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def load_class(cls, identifier, default=None):
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"""
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Loads a single class instance specified by identifier. If identifier
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specifies more than a single class, then logs a warning and returns the first
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class identified.
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If default is not None, will return default if no entry_point matching identifier
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is found. Otherwise, will raise a ModuleMissingError
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"""
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if cls._plugin_cache is None:
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cls._plugin_cache = {}
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if identifier not in cls._plugin_cache:
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identifier = identifier.lower()
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classes = list(pkg_resources.iter_entry_points(cls.entry_point, name=identifier))
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if len(classes) > 1:
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log.warning("Found multiple classes for {entry_point} with identifier {id}: {classes}. Returning the first one.".format(
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entry_point=cls.entry_point,
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id=identifier,
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classes=", ".join(class_.module_name for class_ in classes)))
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if len(classes) == 0:
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if default is not None:
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return default
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raise ModuleMissingError(identifier)
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cls._plugin_cache[identifier] = classes[0].load()
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return cls._plugin_cache[identifier]
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@classmethod
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def load_classes(cls):
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return [class_.load()
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for class_
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in pkg_resources.iter_entry_points(cls.entry_point)]
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class XModule(object):
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''' Implements a generic learning module.
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Subclasses must at a minimum provide a definition for get_html in order to be displayed to users.
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See the HTML module for a simple example.
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'''
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# The default implementation of get_icon_class returns the icon_class attribute of the class
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# This attribute can be overridden by subclasses, and the function can also be overridden
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# if the icon class depends on the data in the module
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icon_class = 'other'
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js = {}
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def __init__(self, system, location, definition, instance_state=None, shared_state=None, **kwargs):
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'''
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Construct a new xmodule
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system: A ModuleSystem allowing access to external resources
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location: Something Location-like that identifies this xmodule
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definition: A dictionary containing 'data' and 'children'. Both are optional
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'data': is JSON-like (string, dictionary, list, bool, or None, optionally nested).
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This defines all of the data necessary for a problem to display that is intrinsic to the problem.
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It should not include any data that would vary between two courses using the same problem
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(due dates, grading policy, randomization, etc.)
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'children': is a list of Location-like values for child modules that this module depends on
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instance_state: A string of serialized json that contains the state of this module for
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current student accessing the system, or None if no state has been saved
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shared_state: A string of serialized json that contains the state that is shared between
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this module and any modules of the same type with the same shared_state_key. This
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state is only shared per-student, not across different students
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kwargs: Optional arguments. Subclasses should always accept kwargs and pass them
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to the parent class constructor.
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Current known uses of kwargs:
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metadata: SCAFFOLDING - This dictionary will be split into several different types of metadata
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in the future (course policy, modification history, etc).
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A dictionary containing data that specifies information that is particular
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to a problem in the context of a course
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'''
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self.system = system
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self.location = Location(location)
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self.definition = definition
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self.instance_state = instance_state
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self.shared_state = shared_state
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self.id = self.location.url()
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self.name = self.location.name
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self.category = self.location.category
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self.metadata = kwargs.get('metadata', {})
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self._loaded_children = None
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def get_name(self):
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name = self.__xmltree.get('name')
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if name:
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return name
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else:
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raise "We should iterate through children and find a default name"
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def get_children(self):
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'''
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Return module instances for all the children of this module.
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'''
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if self._loaded_children is None:
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self._loaded_children = [self.system.get_module(child) for child in self.definition.get('children', [])]
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return self._loaded_children
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def get_display_items(self):
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'''
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Returns a list of descendent module instances that will display immediately
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inside this module
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'''
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items = []
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for child in self.get_children():
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items.extend(child.displayable_items())
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return items
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def displayable_items(self):
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'''
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Returns list of displayable modules contained by this module. If this module
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is visible, should return [self]
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'''
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return [self]
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def get_icon_class(self):
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'''
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Return a css class identifying this module in the context of an icon
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'''
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return self.icon_class
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### Functions used in the LMS
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def get_instance_state(self):
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''' State of the object, as stored in the database
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'''
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return '{}'
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def get_shared_state(self):
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'''
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Get state that should be shared with other instances
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using the same 'shared_state_key' attribute.
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'''
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return '{}'
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def get_score(self):
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''' Score the student received on the problem.
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'''
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return None
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def max_score(self):
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''' Maximum score. Two notes:
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* This is generic; in abstract, a problem could be 3/5 points on one randomization, and 5/7 on another
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* In practice, this is a Very Bad Idea, and (a) will break some code in place (although that code
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should get fixed), and (b) break some analytics we plan to put in place.
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'''
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return None
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def get_progress(self):
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''' Return a progress.Progress object that represents how far the student has gone
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in this module. Must be implemented to get correct progress tracking behavior in
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nesting modules like sequence and vertical.
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If this module has no notion of progress, return None.
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'''
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return None
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def handle_ajax(self, dispatch, get):
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''' dispatch is last part of the URL.
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get is a dictionary-like object '''
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return ""
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# ================================== HTML INTERFACE DEFINITIONS ======================
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@property
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def js_module_name(self):
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return self.__class__.__name__
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@classmethod
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def get_javascript(cls):
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"""
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Return a dictionary containing some of the following keys:
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coffee: A list of coffeescript fragments that should be compiled and
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placed on the page
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js: A list of javascript fragments that should be included on the page
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All of these will be loaded onto the page in the LMS
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"""
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return cls.js
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def get_html(self):
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''' HTML, as shown in the browser. This is the only method that must be implemented
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'''
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raise NotImplementedError("get_html must be defined for all XModules that appear on the screen. Not defined in %s" % self.__class__.__name__)
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class XModuleDescriptor(Plugin):
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"""
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An XModuleDescriptor is a specification for an element of a course. This could
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be a problem, an organizational element (a group of content), or a segment of video,
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for example.
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XModuleDescriptors are independent and agnostic to the current student state on a
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problem. They handle the editing interface used by instructors to create a problem,
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and can generate XModules (which do know about student state).
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"""
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entry_point = "xmodule.v1"
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js = {}
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# A list of metadata that this module can inherit from its parent module
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inheritable_metadata = (
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'graded', 'start', 'due', 'graceperiod', 'showanswer', 'rerandomize',
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# This is used by the XMLModuleStore to provide for locations for static files,
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# and will need to be removed when that code is removed
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'data_dir'
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)
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# A list of descriptor attributes that must be equal for the discriptors to be
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# equal
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equality_attributes = ('definition', 'metadata', 'location', 'shared_state_key', '_inherited_metadata')
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# ============================= STRUCTURAL MANIPULATION ===========================
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def __init__(self,
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system,
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definition=None,
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**kwargs):
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"""
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Construct a new XModuleDescriptor. The only required arguments are the
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system, used for interaction with external resources, and the definition,
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which specifies all the data needed to edit and display the problem (but none
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of the associated metadata that handles recordkeeping around the problem).
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This allows for maximal flexibility to add to the interface while preserving
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backwards compatibility.
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system: An XModuleSystem for interacting with external resources
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definition: A dict containing `data` and `children` representing the problem definition
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Current arguments passed in kwargs:
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location: A xmodule.modulestore.Location object indicating the name and ownership of this problem
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shared_state_key: The key to use for sharing StudentModules with other
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modules of this type
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metadata: A dictionary containing the following optional keys:
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goals: A list of strings of learning goals associated with this module
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display_name: The name to use for displaying this module to the user
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format: The format of this module ('Homework', 'Lab', etc)
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graded (bool): Whether this module is should be graded or not
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start (string): The date for which this module will be available
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due (string): The due date for this module
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graceperiod (string): The amount of grace period to allow when enforcing the due date
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showanswer (string): When to show answers for this module
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rerandomize (string): When to generate a newly randomized instance of the module data
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"""
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self.system = system
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self.metadata = kwargs.get('metadata', {})
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self.definition = definition if definition is not None else {}
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self.location = Location(kwargs.get('location'))
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self.name = self.location.name
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self.category = self.location.category
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self.shared_state_key = kwargs.get('shared_state_key')
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self._child_instances = None
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self._inherited_metadata = set()
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def inherit_metadata(self, metadata):
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"""
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Updates this module with metadata inherited from a containing module.
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Only metadata specified in self.inheritable_metadata will
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be inherited
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"""
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# Set all inheritable metadata from kwargs that are
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# in self.inheritable_metadata and aren't already set in metadata
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for attr in self.inheritable_metadata:
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if attr not in self.metadata and attr in metadata:
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self._inherited_metadata.add(attr)
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self.metadata[attr] = metadata[attr]
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def get_children(self):
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"""Returns a list of XModuleDescriptor instances for the children of this module"""
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if self._child_instances is None:
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self._child_instances = []
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for child_loc in self.definition.get('children', []):
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child = self.system.load_item(child_loc)
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child.inherit_metadata(self.metadata)
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self._child_instances.append(child)
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return self._child_instances
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def xmodule_constructor(self, system):
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"""
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Returns a constructor for an XModule. This constructor takes two arguments:
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instance_state and shared_state, and returns a fully nstantiated XModule
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"""
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return partial(
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self.module_class,
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system,
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self.location,
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self.definition,
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metadata=self.metadata
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)
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# ================================= JSON PARSING ===================================
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@staticmethod
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def load_from_json(json_data, system, default_class=None):
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"""
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This method instantiates the correct subclass of XModuleDescriptor based
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on the contents of json_data.
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json_data must contain a 'location' element, and must be suitable to be
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passed into the subclasses `from_json` method.
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"""
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class_ = XModuleDescriptor.load_class(
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json_data['location']['category'],
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default_class
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)
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return class_.from_json(json_data, system)
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@classmethod
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def from_json(cls, json_data, system):
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"""
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Creates an instance of this descriptor from the supplied json_data.
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This may be overridden by subclasses
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json_data: A json object specifying the definition and any optional keyword arguments for
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the XModuleDescriptor
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system: An XModuleSystem for interacting with external resources
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"""
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return cls(system=system, **json_data)
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# ================================= XML PARSING ====================================
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@staticmethod
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def load_from_xml(xml_data,
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system,
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org=None,
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course=None,
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default_class=None):
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"""
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This method instantiates the correct subclass of XModuleDescriptor based
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on the contents of xml_data.
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xml_data must be a string containing valid xml
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system is an XMLParsingSystem
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org and course are optional strings that will be used in the generated modules
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url identifiers
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"""
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class_ = XModuleDescriptor.load_class(
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etree.fromstring(xml_data).tag,
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default_class
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)
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# leave next line in code, commented out - useful for low-level debugging
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# log.debug('[XModuleDescriptor.load_from_xml] tag=%s, class_=%s' % (etree.fromstring(xml_data).tag,class_))
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return class_.from_xml(xml_data, system, org, course)
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@classmethod
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def from_xml(cls, xml_data, system, org=None, course=None):
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"""
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Creates an instance of this descriptor from the supplied xml_data.
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This may be overridden by subclasses
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xml_data: A string of xml that will be translated into data and children for
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this module
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system is an XMLParsingSystem
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org and course are optional strings that will be used in the generated modules
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url identifiers
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"""
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raise NotImplementedError('Modules must implement from_xml to be parsable from xml')
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def export_to_xml(self, resource_fs):
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"""
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Returns an xml string representing this module, and all modules underneath it.
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May also write required resources out to resource_fs
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Assumes that modules have single parantage (that no module appears twice in the same course),
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and that it is thus safe to nest modules as xml children as appropriate.
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The returned XML should be able to be parsed back into an identical XModuleDescriptor
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using the from_xml method with the same system, org, and course
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"""
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raise NotImplementedError('Modules must implement export_to_xml to enable xml export')
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# ================================== HTML INTERFACE DEFINITIONS ======================
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@property
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def js_module_name(self):
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return self.__class__.__name__
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@classmethod
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def get_javascript(cls):
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"""
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Return a dictionary containing some of the following keys:
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coffee: A list of coffeescript fragments that should be compiled and
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placed on the page
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js: A list of javascript fragments that should be included on the page
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All of these will be loaded onto the page in the CMS
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"""
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return cls.js
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def get_html(self):
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"""
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Return the html used to edit this module
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"""
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raise NotImplementedError("get_html() must be provided by specific modules")
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# =============================== Testing ===================================
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def get_sample_state(self):
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"""
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Return a list of tuples of instance_state, shared_state. Each tuple defines a test/sample case for this module
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"""
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return [('{}', '{}')]
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# =============================== BUILTIN METHODS ===========================
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def __eq__(self, other):
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eq = (self.__class__ == other.__class__ and
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all(getattr(self, attr, None) == getattr(other, attr, None)
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for attr in self.equality_attributes))
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if not eq:
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for attr in self.equality_attributes:
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print getattr(self, attr, None), getattr(other, attr, None), getattr(self, attr, None) == getattr(other, attr, None)
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return eq
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def __repr__(self):
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return "{class_}({system!r}, {definition!r}, location={location!r}, metadata={metadata!r})".format(
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class_=self.__class__.__name__,
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system=self.system,
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definition=self.definition,
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location=self.location,
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metadata=self.metadata
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)
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class DescriptorSystem(object):
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def __init__(self, load_item, resources_fs, **kwargs):
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"""
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load_item: Takes a Location and returns an XModuleDescriptor
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resources_fs: A Filesystem object that contains all of the
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resources needed for the course
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"""
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self.load_item = load_item
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self.resources_fs = resources_fs
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class XMLParsingSystem(DescriptorSystem):
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def __init__(self, load_item, resources_fs, process_xml, **kwargs):
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"""
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process_xml: Takes an xml string, and returns the the XModuleDescriptor created from that xml
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"""
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DescriptorSystem.__init__(self, load_item, resources_fs)
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self.process_xml = process_xml
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class ModuleSystem(object):
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'''
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This is an abstraction such that x_modules can function independent
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of the courseware (e.g. import into other types of courseware, LMS,
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or if we want to have a sandbox server for user-contributed content)
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ModuleSystem objects are passed to x_modules to provide access to system
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functionality.
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Note that these functions can be closures over e.g. a django request
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and user, or other environment-specific info.
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'''
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def __init__(self, ajax_url, track_function,
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get_module, render_template, replace_urls,
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user=None, filestore=None, debug=False, xqueue_callback_url=None):
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'''
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Create a closure around the system environment.
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ajax_url - the url where ajax calls to the encapsulating module go.
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track_function - function of (event_type, event), intended for logging
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or otherwise tracking the event.
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TODO: Not used, and has inconsistent args in different
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files. Update or remove.
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get_module - function that takes (location) and returns a corresponding
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module instance object.
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render_template - a function that takes (template_file, context), and returns
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rendered html.
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user - The user to base the random number generator seed off of for this request
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filestore - A filestore ojbect. Defaults to an instance of OSFS based at
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settings.DATA_DIR.
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replace_urls - TEMPORARY - A function like static_replace.replace_urls
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that capa_module can use to fix up the static urls in ajax results.
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'''
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self.ajax_url = ajax_url
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self.xqueue_callback_url = xqueue_callback_url
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self.track_function = track_function
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self.filestore = filestore
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self.get_module = get_module
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self.render_template = render_template
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self.DEBUG = self.debug = debug
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self.seed = user.id if user is not None else 0
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self.replace_urls = replace_urls
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def get(self, attr):
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''' provide uniform access to attributes (like etree).'''
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return self.__dict__.get(attr)
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def set(self, attr, val):
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'''provide uniform access to attributes (like etree)'''
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self.__dict__[attr] = val
|
|
|
|
def __repr__(self):
|
|
return repr(self.__dict__)
|
|
|
|
def __str__(self):
|
|
return str(self.__dict__)
|
|
|