# python standard library from contextlib import contextmanager # `with` statement in db sessions import logging from os import path, sys from datetime import datetime # user installed libraries import bcrypt from sqlalchemy import create_engine from sqlalchemy.orm import sessionmaker import networkx as nx import yaml # this project from models import Student, Answer, Topic, StudentTopic from knowledge import StudentKnowledge from factory import QFactory from tools import load_yaml # setup logger for this module logger = logging.getLogger(__name__) class LearnAppException(Exception): pass # ============================================================================ # LearnApp - application logic # ============================================================================ class LearnApp(object): def __init__(self, conffile): # state of online students self.online = {} # dependency graph shared by all students self.deps = build_dependency_graph(conffile) # connect to database and checks for registered students self.db_setup(self.deps.graph['database']) # add topics from dependency graph to the database, if missing self.db_add_topics() # ------------------------------------------------------------------------ # login # ------------------------------------------------------------------------ def login(self, uid, try_pw): with self.db_session() as s: student = s.query(Student).filter(Student.id == uid).one_or_none() if student is None: logger.info(f'User "{uid}" does not exist.') return False # student does not exist hashedtry = bcrypt.hashpw(try_pw.encode('utf-8'), student.password) if hashedtry != student.password: logger.info(f'User "{uid}" wrong password.') return False # wrong password # success logger.info(f'User "{uid}" logged in') tt = s.query(StudentTopic).filter(StudentTopic.student_id == uid) state = {} for t in tt: state[t.topic_id] = { 'level': t.level, 'date': datetime.strptime(t.date, "%Y-%m-%d %H:%M:%S.%f"), } self.online[uid] = { 'name': student.name, 'number': student.id, 'state': StudentKnowledge(self.deps, state=state) } return True # ------------------------------------------------------------------------ # logout # ------------------------------------------------------------------------ def logout(self, uid): state = self.online[uid]['state'].state # dict {node:level,...} # save state to database with self.db_session(autoflush=False) as s: # update existing associations and remove from state dict for a in s.query(StudentTopic).filter_by(student_id=uid): if a.topic_id in state: d = state.pop(a.topic_id) a.level = d['level'] #state.pop(a.topic_id) # update a.date = str(d['date']) s.add(a) # insert the remaining ones u = s.query(Student).get(uid) for n,d in state.items(): a = StudentTopic(level=d['level'], date=str(d['date'])) t = s.query(Topic).get(n) if t is None: # create if topic doesn't exist yet t = Topic(id=n) a.topic = t u.topics.append(a) s.add(a) del self.online[uid] logger.info(f'User "{uid}" logged out') # ------------------------------------------------------------------------ # change_password # ------------------------------------------------------------------------ def change_password(self, uid, pw): if not pw: return False with self.db_session() as s: u = s.query(Student).get(uid) u.password = bcrypt.hashpw(pw.encode('utf-8'), bcrypt.gensalt()) logger.info(f'User "{uid}" changed password') return True # ------------------------------------------------------------------------ # check answer and if correct returns new question, otherwise returns None # ------------------------------------------------------------------------ def check_answer(self, uid, answer): knowledge = self.online[uid]['state'] q = knowledge.check_answer(answer) with self.db_session() as s: s.add(Answer( ref=q['ref'], grade=q['grade'], starttime=str(q['start_time']), finishtime=str(q['finish_time']), student_id=uid)) s.commit() return q['grade'] # ------------------------------------------------------------------------ # Start new topic # ------------------------------------------------------------------------ def start_topic(self, uid, topic): self.online[uid]['state'].init_topic(topic) # ------------------------------------------------------------------------ # Fill db table 'Topic' with topics from the graph if not already there. # ------------------------------------------------------------------------ def db_add_topics(self): with self.db_session() as s: tt = [t[0] for t in s.query(Topic.id)] # db list of topics nn = self.deps.nodes() # topics in the graph s.add_all([Topic(id=n) for n in nn if n not in tt]) # ------------------------------------------------------------------------ # setup and check database # ------------------------------------------------------------------------ def db_setup(self, db): engine = create_engine(f'sqlite:///{db}', echo=False) self.Session = sessionmaker(bind=engine) try: with self.db_session() as s: n = s.query(Student).count() except Exception as e: logger.critical(f'Database "{db}" not usable.') sys.exit(1) else: logger.info(f'Database "{db}" has {n} students.') # ------------------------------------------------------------------------ # helper to manage db sessions using the `with` statement, for example # with self.db_session() as s: s.query(...) # ------------------------------------------------------------------------ @contextmanager def db_session(self, **kw): session = self.Session(**kw) try: yield session session.commit() except Exception as e: session.rollback() raise e finally: session.close() # ======================================================================== # methods that do not change state (pure functions) # ======================================================================== # ------------------------------------------------------------------------ def get_student_name(self, uid): return self.online[uid].get('name', '') # ------------------------------------------------------------------------ def get_student_state(self, uid): return self.online[uid]['state'].get_knowledge_state() # ------------------------------------------------------------------------ def get_student_progress(self, uid): return self.online[uid]['state'].get_topic_progress() # ------------------------------------------------------------------------ def get_student_question(self, uid): return self.online[uid]['state'].get_current_question() # dict # ------------------------------------------------------------------------ def get_student_question_type(self, uid): return self.online[uid]['state'].get_current_question()['type'] # ------------------------------------------------------------------------ def get_student_topic(self, uid): return self.online[uid]['state'].get_current_topic() # str # ------------------------------------------------------------------------ def get_title(self): return self.deps.graph['title'] # ------------------------------------------------------------------------ def get_topic_name(self, ref): return self.deps.node[ref]['name'] # ------------------------------------------------------------------------ def get_current_public_dir(self, uid): topic = self.online[uid]['state'].get_current_topic() p = self.deps.graph['path'] return path.join(p, topic, 'public') # ============================================================================ # Given configuration file, loads YAML on that file and builds a digraph. # First, topics such as `computer/mips/exceptions` are added as nodes # together with dependencies. Then, questions are loaded to a factory. # # g.graph['path'] base path where topic directories are located # g.graph['title'] title defined in the configuration YAML # g.graph['database'] sqlite3 database file to use # # Nodes are the topic references e.g. 'my/topic' # g.node['my/topic']['name'] name of the topic # g.node['my/topic']['questions'] list of question refs defined in YAML # g.node['my/topic']['factory'] dict with question factories # ---------------------------------------------------------------------------- def build_dependency_graph(config_file): # Load configuration file to a dict try: with open(config_file, 'r') as f: config = yaml.load(f) except FileNotFoundError: logger.critical(f'File not found: "{config_file}"') raise LearnAppException except yaml.scanner.ScannerError as err: logger.critical(f'Parsing YAML file "{config_file}": {err}') raise LearnAppException else: logger.info(f'Configuration file "{config_file}"') # create graph prefix = config.get('path', '.') title = config.get('title', '') database = config.get('database', 'students.db') g = nx.DiGraph(path=prefix, title=title, database=database) # iterate over topics and build graph topics = config.get('topics', {}) for ref,attr in topics.items(): g.add_node(ref) if isinstance(attr, dict): g.node[ref]['name'] = attr.get('name', ref) g.node[ref]['questions'] = attr.get('questions', []) g.add_edges_from((d,ref) for d in attr.get('deps', [])) # iterate over topics and create question factories logger.info('Loading:') for tref in g.nodes(): tnode = g.node[tref] # current node (topic) fullpath = path.expanduser(path.join(prefix, tref)) filename = path.join(fullpath, 'questions.yaml') loaded_questions = load_yaml(filename, default=[]) # list # if questions not in configuration then load all, preserving order if not tnode['questions']: tnode['questions'] = [q['ref'] for q in loaded_questions] # make questions factory (without repeating same question) tnode['factory'] = {} for q in loaded_questions: if q['ref'] in tnode['questions']: q['path'] = fullpath tnode['factory'][q['ref']] = QFactory(q) logger.info(f'{len(tnode["questions"]):4} questions from {tref}') return g