8039e40f47
This code was originally located at: ./openedx/core/djangoapps/coursegraph However, code makes more sense within the ./cms tree, because: * it is responsible for publishing course content to an external system, with is within the responsibilities of CMS, and * is uses modulestore, which is discouraged for use in LMS (see 0011-limit-modulestore-use-in-lms.rst). So, we move the code to: ./cms/djangoapps/coursegraph and uninstall coursegraph from LMS. We do not expect this refactor to have any breaking downstream effects.
124 lines
3.8 KiB
Python
124 lines
3.8 KiB
Python
"""
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Utilities for testing the dump_to_neo4j management command
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"""
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from py2neo import Node
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class MockGraph:
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"""
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A stubbed out version of py2neo's Graph object, used for testing.
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Args:
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transaction_errors: a bool for whether transactions should throw
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an error.
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"""
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def __init__(self, transaction_errors=False, **kwargs): # pylint: disable=unused-argument
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self.nodes = set()
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self.number_commits = 0
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self.number_rollbacks = 0
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self.transaction_errors = transaction_errors
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def begin(self):
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"""
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A stub of the method that generates transactions
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Returns: a MockTransaction object (instead of a py2neo Transaction)
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"""
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return MockTransaction(self)
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def commit(self, transaction):
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"""
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Takes elements in the mock transaction's temporary storage and adds them
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to this mock graph's storage. Throws an error if this graph's
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transaction_errors param is set to True.
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"""
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if self.transaction_errors:
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raise Exception("fake exception while trying to commit")
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for element in transaction.temp:
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self.nodes.add(element)
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transaction.temp.clear()
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self.number_commits += 1
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def rollback(self, transaction):
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"""
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Clears the transactions temporary storage
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"""
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transaction.temp.clear()
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self.number_rollbacks += 1
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class MockTransaction:
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"""
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A stubbed out version of py2neo's Transaction object, used for testing.
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"""
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def __init__(self, graph):
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self.temp = set()
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self.graph = graph
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def run(self, query):
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"""
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Deletes all nodes associated with a course. Normally `run` executes
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an arbitrary query, but in our code, we only use it to delete nodes
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associated with a course.
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Args:
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query: query string to be executed (in this case, to delete all
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nodes associated with a course)
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"""
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start_string = "WHERE n.course_key='"
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start = query.index(start_string) + len(start_string)
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query = query[start:]
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end = query.find("'")
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course_key = query[:end]
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self.graph.nodes = {
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node for node in self.graph.nodes if node['course_key'] != course_key
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}
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def create(self, element):
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"""
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Adds elements to the transaction's temporary backend storage
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Args:
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element: a py2neo Node object
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"""
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if isinstance(element, Node):
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self.temp.add(element)
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class MockNodeMatcher:
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"""
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Mocks out py2neo's NodeMatcher class. Used to match a node from a graph.
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py2neo's NodeMatcher expects a real graph object to run queries against,
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so, rather than have to mock out MockGraph to accommodate those queries,
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it seemed simpler to mock out NodeMatcher as well.
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"""
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def __init__(self, graph):
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self.graph = graph
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def match(self, label, course_key):
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"""
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Selects nodes that match a label and course_key
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Args:
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label: the string of the label we're selecting nodes by
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course_key: the string of the course key we're selecting node by
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Returns: a MockResult of matching nodes
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"""
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nodes = []
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for node in self.graph.nodes:
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if node.has_label(label) and node["course_key"] == course_key:
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nodes.append(node)
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return MockNodeMatch(nodes)
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class MockNodeMatch(list):
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"""
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Mocks out py2neo's NodeMatch class: this is the type of what
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MockNodeMatcher's `match` method returns.
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"""
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def first(self):
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"""
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Returns: the first element of a list if the list has elements.
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Otherwise, None.
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"""
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return self[0] if self else None
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