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# To use redis
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import redis
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# To generate some Id for course and persons
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import uuid
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# To create the index to setup the search feature
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from redis_app.utils.index import create_index
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# Constants
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# Will expire after 300s = 5 mins
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DEFAULT_EXPIRE_TIME = 300
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# The refresh add 60s = 1 min
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EXPIRE_REFRESH_TIME = 60
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# Setting up the redis connection to localhost!6379
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redis_connection = redis.Redis(host='localhost', port=6379, decode_responses=True)
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# Setting up the redis pubsub system
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pub_sub = redis_connection.pubsub()
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# Creating the index for the search feature
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create_index(redis_connection)
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####################################################################################
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# - PERSONS - #
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####################################################################################
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# Allows to get the person with the name and the role (because with a name and a role, the person is unique)
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def getPersonIdNameRole(name, role):
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# Defining the query for Redis Stack
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query = f"@name:{name} @role:{role}"
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# Searching with redis Stack
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results = redis_connection.execute_command('FT.SEARCH', 'idx:persons', query)
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# results[0] contains the number of elements. If it's greater than 0, there's at least a result
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if results[0] > 0:
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# Taking the first result
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person_key = results[1]
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return person_key
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# No person found
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return False
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# Gets the person id with the person object (which obviously doesn't contain the id)
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def getPersonId(person):
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return getPersonIdNameRole(person["name"], person["role"])
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# Gets the whole person object with the person id
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def getPerson(person_id):
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return redis_connection.hgetall(f"person:{person_id}")
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# Allows a user to register
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def register_redis(name, role):
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# Defining the query for Redis Stack
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query = f"@name:{name} @role:{role}"
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# Searching with redis Stack
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results = redis_connection.execute_command('FT.SEARCH', 'idx:persons', query)
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# results[0] contains the number of elements. If it's greater than 0, there's at least a result
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if results[0] > 0:
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# The user already exists.
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return False
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# Creating the person_key
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person_key = f"person:{get_uuid4()}"
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# And assigning correct information
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redis_connection.hset(person_key, mapping={
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'name': name,
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'role': role
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})
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# Retrieving the user just created (we're sure it's been well created with this approach)
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return redis_connection.hgetall(person_key)
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# Allows a user to login
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def login_redis(name, role):
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# We just check if the user exists
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return getPersonIdNameRole(name, role)
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# Allows to change the profile of a user. person_id = current person id, name = name requested, role = role requested
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def changeProfile_redis(person_id, name, role):
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# Checking if the name and role requested is not already associated to a user
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new_person_id = getPersonIdNameRole(name, role)
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if new_person_id:
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return False
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# Setting the new information
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redis_connection.hmset(person_id, mapping={"name": name, "role": role})
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# Retrieving the user by spliting the id (because the id is person:id and we only want id)
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return getPerson(person_id.split(':')[1])
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####################################################################################
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# - COURSES - #
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####################################################################################
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# Is a course expired?
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def isExpired(course_id):
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# Checking the time to live of a course
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ttl = redis_connection.ttl(f"course:{course_id}")
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# If the ttl is -2 (key doesn't exist) or 0 (no ttl), the key is expired (or does not exist at all)
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if ttl == -2 or ttl == 0: # If -1, the key has no expiration
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return True
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return False
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# Is the course full? Is there a place for a new student?
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def isCourseFull(course):
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students = course.get('students', '') # Because it crashes with ['students'], we have to put a default value: '' here
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if not students:
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# No one is registered, and since the minimum of place for a course is 1, it's not full
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return False
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try:
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# We want an int to compare
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places = int(course['places'])
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# Checking the length of the course's students list, if it's >= course's number of places
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if len(students.split(',')) >= places:
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return True
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return False
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except:
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# Places are not an int, so it's not full (because I had to choose, I choose that if it's wrongly setup, everybody can just register infinitely).
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return False
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# Gets the id of the whole course object (obviously without the id in it)
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def getCourseId(course):
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# Setting up the query to search with redis Stack
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query = f"@title:{course['title']} @teacher:{course['teacher']}"
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# Searching with Redis Stack
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results = redis_connection.execute_command('FT.SEARCH', 'idx:courses', query)
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# If the number of results > 0
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if results[0] > 0:
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# Returning the first course
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course_key = results[1]
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return course_key
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# No course found
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return False
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# Gets the whole course object with the course_id
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def getCourse(course_id):
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return redis_connection.hgetall(f"course:{course_id}")
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# Deleting a course
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def delete_course(course_id):
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# Checking if the course exists
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course = redis_connection.hgetall(f"course:{course_id}")
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if not course:
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# Does not exist
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return False
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# Deleting it
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redis_connection.delete(f"course:{course_id}")
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return True
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# Creates a course by taking the title, the summary, the level, the number of places and the teacher id
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def create_course(course_title, course_summary, course_level, course_places, course_teacher):
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# Setting up the course id
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course_id = get_uuid4()
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# Setting the new course into Redis (2 courses can be identical, there's no unicity)
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redis_connection.hset(f"course:{course_id}", mapping={
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"title": course_title,
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"summary": course_summary,
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"level": course_level,
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"places": course_places,
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"teacher": course_teacher # Id of the teacher without the person:, only the uuid
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})
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# Expire after DEFAULT_EXPIRE_TIME seconds
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redis_connection.expire(f"course:{course_id}", DEFAULT_EXPIRE_TIME)
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# Updates a course by taking the title, the summary, the level, the number of places and the teacher id
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def update_course(course_id, course_title, course_summary, course_level, course_places, course_teacher):
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# Updating the course into Redis (2 courses can be identical, there's no unicity)
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redis_connection.hset(f"course:{course_id}", mapping={
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"title": course_title,
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"summary": course_summary,
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"level": course_level,
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"places": course_places,
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"teacher": course_teacher
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})
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# Expire after DEFAULT_EXPIRE_TIME seconds
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redis_connection.expire(f"course:{course_id}", DEFAULT_EXPIRE_TIME)
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# Publishing the update to notify every students (and the teacher)
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publish(course_id, f"UPDATE: Course:{course_id} is now: Title: {course_title}, Summary: {course_summary}, Level: {course_level}, Places: {course_places}, Teacher: {course_teacher}")
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# Registering to a course
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def course_register(course_id, person_id):
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# Checking if the course and the person exists
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course = redis_connection.hgetall(f"course:{course_id}")
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person = redis_connection.hgetall(f"person:{person_id}")
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if not course or not person:
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# One or both don't exist
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return False
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# Taking the students of the course
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students = course.get('students', '')
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# Checking if the user is not already registered
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if person_id in students.split(','):
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# He's registered
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return True
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# Checking if the course is full
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if isCourseFull(course):
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return False
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# if there's not student registered to the course, adding the person id to it
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if not students:
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new_students = person_id
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else:
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# There's at least one other student registered, so we're adding the person id after a coma to separate ids
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new_students = students + "," + person_id
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# Setting the new students list
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redis_connection.hset(f"course:{course_id}", "students", new_students)
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refresh_expire(course_id)
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return True
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def course_unregister(course_id, person_id):
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# Checking if the course and the person exists
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course = redis_connection.hgetall(f"course:{course_id}")
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person = redis_connection.hgetall(f"person:{person_id}")
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if not course or not person:
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# One or both don't exist
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return False
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# Taking the students of the course
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students = course.get('students', '')
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# Checking if the user is registered
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if person_id not in students.split(','):
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# Not registered, so it's all good
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return True
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# Creating a list of all students by spliting it by the coma
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students_list = students.split(",")
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# If there's only one person (which must be the person asking to unregister because he's in the list and there's only one person)
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if len(students_list) == 1:
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# The new list is empty
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new_students = ""
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else:
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# Creating a list of person id separated with comas of all students in the list except the person_id one
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new_students = ",".join([student for student in students_list if student != person_id])
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# Setting up the new list of students for the course
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redis_connection.hset(f"course:{course_id}", "students", new_students)
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return True
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# Allows to refresh the course ttl when someone register to the course
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def refresh_expire(course_id):
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# Checking if the course exists
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course = redis_connection.hgetall(f"course:{course_id}")
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if not course:
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# Does not exist
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return False
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# Checking the ttl
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ttl = redis_connection.ttl(f"course:{course_id}")
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if ttl <= 0:
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# ttl is < 0 so it's expired, or does not exist at all, or has an infinite ttl
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return False
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# Adding to the current ttl EXPIRE_REFRESH_TIME seconds for the course_id
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redis_connection.expire(f"course:{course_id}", ttl + EXPIRE_REFRESH_TIME)
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return True
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####################################################################################
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# - LINKS - #
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####################################################################################
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# Gets the courses of a person by its id
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def getCoursesFromPerson(person_id):
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# Getting all of courses keys (not into person object because even if we use redis, which is a NoSQL technology, I really wanted to
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# stay the most consistent I could by not having two lists for the same data. For example, the courses has a students list. If the students would have
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# a courses list, the data would have been duplicated, for no reason except the efficience. I decided not to take the risk to duplicate this data
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# because I strongly believe that it will stay optimized enough to iterate over all courses. Also, I decided to put the list for the courses because
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# generally there will be more students than courses (because for one course, there's around 30 students), so iterate over the persons (students) would have
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# been less efficient than over courses. This is only a choiceof implementation. I could obviously be wrong. But that's my choice, and of course this choice
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# could change at the same time as my project lives)
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course_keys = redis_connection.keys(f"course:*")
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courses = []
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# Checking if the person exists
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person = redis_connection.hgetall(f"person:{person_id}")
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if not person:
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# Does not exist, returning an empty array
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return []
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# For each course key in Redis
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for key in course_keys:
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# Getting the data of the course key
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course_data = redis_connection.hgetall(key)
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# When the user is a student
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if person['role'] == "Student":
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# We're only interested about courses where the student is
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if person_id in course_data.get('students', '').split(","):
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# Getting the course id
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course_id = getCourseId(course_data)
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if course_id == False:
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# Didn't work, continuing not to break the feature
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continue
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# Adding the id manually the course object
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course_data['id'] = course_id.split(":")[1]
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# Adding the course object to the courses list we will return
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courses.append(course_data)
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# When the user is a teacher
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else:
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# taking the teacher id of the courses
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teacher_id = course_data["teacher"]
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# We're only interested in courses where the teacher is the teacher of the course
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if teacher_id == person_id:
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# Getting the course idc
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course_id = getCourseId(course_data)
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if course_id == False:
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# Didn't work, continuing not to break the feature
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continue
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# Adding the id manually the course object
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course_data['id'] = course_id.split(":")[1]
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# Adding the course object to the courses list we will return
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courses.append(course_data)
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# Returning the courses found
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return courses
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# Is the person registered to the course?
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def isPersonRegisteredToCourse(course, person):
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# Checking if the person or the course is not False, or ""
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if not person or not course:
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# Not a person or a course
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return False
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# Getting the person id
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person_id = getPersonId(person).split(":")[1]
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if not person_id:
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# Not found
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return False
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# Getting the course id
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course_id = getCourseId(course)
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if not course_id:
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# Not found
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return False
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# Iterating over each course keys in Redis
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course_keys = redis_connection.keys(f"course:*")
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for key in course_keys:
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# Getting the course data
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course_data = redis_connection.hgetall(key)
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# If the person is a student (because a teacher can't register to a course)
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if person['role'] == "Student":
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# And if the person is in the students list of the course
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if person_id in course_data.get('students', '').split(","):
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# Getting the course id of the current course
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current_course_id = getCourseId(course_data)
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if current_course_id == False:
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# Didn't work, continuing not to break the feature
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continue
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# Checking if the current course id equals the course id requested
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if course_id == current_course_id:
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# The student is in the current course and the current course has the same id as the course id requested
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return True
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# After iterating over all keys, the students is not into the course_id
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return False
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####################################################################################
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# - UTILS - #
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####################################################################################
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# Creating an uuid
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def get_uuid4():
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# We remove the - because it creates a lot of problems into redis for the search feature
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return str(uuid.uuid4()).replace('-', '')
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# Publish a message for a course
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def publish(course_id, message):
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# Publishing the message "message" into the channel course_id
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redis_connection.publish(course_id, message)
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# Subscribe to courses id, to get a message
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def get_message(*courses_id):
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# Unsubscribe to everything in case there's still some subscribe before
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pub_sub.punsubscribe()
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# Subscriing to the whole list of courses id (which corresponds to channels)
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pub_sub.psubscribe(*courses_id)
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# Listening for new messages
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for message in pub_sub.listen():
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# Checking if the message if a message as we published
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if message["type"] != 'pmessage':
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# Not a message that is interesting for us
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continue
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# Found an interesting message!
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break
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# Returning this message
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return message
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# Searching feature, to search with a list of keywords
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def search_redis(keywords):
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# List of courses found matching with keywords
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courses = []
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# For every keyword in the list of keywords separating with spaces
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for keyword in keywords.split(' '):
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if not keyword: # When the users end his keywords with a ' '
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continue
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# Setting up queries for title, summary, level and teacher id (good luck for this one, searching the exact person id is not an easy task)
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title_query = f"@title:{keyword}"
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summary_query = f"@summary:{keyword}"
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level_query = f"@level:{keyword}"
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teacher_query = f"@teacher:{keyword}"
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# Searching into the indexes of the course
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title_results = redis_connection.execute_command('FT.SEARCH', 'idx:courses', title_query)
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summary_results = redis_connection.execute_command('FT.SEARCH', 'idx:courses', summary_query)
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level_results = redis_connection.execute_command('FT.SEARCH', 'idx:courses', level_query)
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teacher_results = redis_connection.execute_command('FT.SEARCH', 'idx:courses', teacher_query)
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# The redis Stack search returns as the first element the number of elements, then returns the course every 2 lines.
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# I think the best way to understand it is by trying it.
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for i in range(1, len(title_results), 2):
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courses.append(title_results[i])
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for i in range(1, len(summary_results), 2):
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courses.append(summary_results[i])
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for i in range(1, len(level_results), 2):
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courses.append(level_results[i])
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for i in range(1, len(teacher_results), 2):
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courses.append(teacher_results[i])
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# Returning a list with unique values (not returning 2 times the same one)
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courses_set = set(courses)
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return list(courses_set) |
