This project is a start of the journey to create
a full stack web application. It was completed in
a team of two great software engineers (ThankGod
Ugobo and Samwel Mwawasi) from #C12.
Welcome to the AirBnB clone project! Before starting, please read the AirBnB concept page.
First step: Write a command interpreter to manage your AirBnB objects. This is the first step towards building your first full web application: the AirBnB clone. This first step is very important because you will use what you build during this project with all other following projects: HTML/CSS templating, database storage, API, front-end integration…
Each task is linked and will help you to:
put in place a parent class (called BaseModel) to take care of the initialization, serialization and deserialization of your future instances create a simple flow of serialization/deserialization: Instance <-> Dictionary <-> JSON string <-> file create all classes used for AirBnB (User, State, City, Place…) that inherit from BaseModel create the first abstracted storage engine of the project: File storage. create all unittests to validate all our classes and storage engine What’s a command interpreter? Do you remember the Shell? It’s exactly the same but limited to a specific use-case. In our case, we want to be able to manage the objects of our project:
Create a new object (ex: a new User or a new Place) Retrieve an object from a file, a database etc… Do operations on objects (count, compute stats, etc…) Update attributes of an object Destroy an object
cmd module(https://docs.python.org/3.8/library/cmd.html) cmd module in depth(https://pymotw.com/2/cmd/) packages concept page uuid module(https://docs.python.org/3.8/library/uuid.html) datetime(https://docs.python.org/3.8/library/datetime.html) unittest module(https://docs.python.org/3.8/library/unittest.html#module-unittest) args/kwargs(https://yasoob.me/2013/08/04/args-and-kwargs-in-python-explained/) Python test cheatsheet(https://www.pythonsheets.com/notes/python-tests.html) cmd module wiki page(https://wiki.python.org/moin/CmdModule) python unittest(https://realpython.com/python-testing/) Packages(https://docs.python.org/3.4/tutorial/modules.html#packages)
Python Unit Tests Allowed editors: vi, vim, emacs All your files should end with a new line All your test files should be inside a folder tests You have to use the unittest module All your test files should be python files (extension: .py) All your test files and folders should start by test_ Your file organization in the tests folder should be the same as your project e.g., For models/base_model.py, unit tests must be in: tests/test_models/test_base_model.py e.g., For models/user.py, unit tests must be in: tests/test_models/test_user.py All your tests should be executed by using this command: python3 -m unittest discover tests You can also test file by file by using this command: python3 -m unittest tests/test_models/test_base_model.py All your modules should have a documentation (python3 -c 'print(import("my_module").doc)') All your classes should have a documentation (python3 -c 'print(import("my_module").MyClass.doc)') All your functions (inside and outside a class) should have a documentation (python3 -c 'print(import("my_module").my_function.doc)' and python3 -c 'print(import("my_module").MyClass.my_function.doc)') We strongly encourage you to work together on test cases, so that you don’t miss any edge case
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Write a README.md: description of the project description of the command interpreter: how to start it how to use it examples You should have an AUTHORS file at the root of your repository, listing all individuals having contributed content to the repository. For format, reference Docker’s AUTHORS page You should use branches and pull requests on GitHub - it will help you as team to organize your work
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Write beautiful code that passes the pycodestyle checks.
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All your files, classes, functions must be tested with unit tests
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Write a class BaseModel that defines all common attributes/methods for other classes:
models/base_model.py Public instance attributes: id: string - assign with an uuid when an instance is created: you can use uuid.uuid4() to generate unique id but don’t forget to convert to a string the goal is to have unique id for each BaseModel created_at: datetime - assign with the current datetime when an instance is created updated_at: datetime - assign with the current datetime when an instance is created and it will be updated every time you change your object str: should print: [] (<self.id>) <self.dict> Public instance methods: save(self): updates the public instance attribute updated_at with the current datetime to_dict(self): returns a dictionary containing all keys/values of dict of the instance: by using self.dict, only instance attributes set will be returned a key class must be added to this dictionary with the class name of the object created_at and updated_at must be converted to string object in ISO format: format: %Y-%m-%dT%H:%M:%S.%f (ex: 2017-06-14T22:31:03.285259) you can use isoformat() of datetime object This method will be the first piece of the serialization/deserialization process: create a dictionary representation with “simple object type” of our BaseModel
- Previously we created a method to generate a dictionary representation of an instance (method to_dict()).
Now it’s time to re-create an instance with this dictionary representation. Update models/base_model.py:
init(self, *args, **kwargs): you will use *args, **kwargs arguments for the constructor of a BaseModel. (more information inside the AirBnB clone concept page) *args won’t be used if kwargs is not empty: each key of this dictionary is an attribute name (Note class from kwargs is the only one that should not be added as an attribute. See the example output, below) each value of this dictionary is the value of this attribute name Warning: created_at and updated_at are strings in this dictionary, but inside your BaseModel instance is working with datetime object. You have to convert these strings into datetime object. Tip: you know the string format of these datetime otherwise: create id and created_at as you did previously (new instance)
- Now we can recreate a BaseModel from another one by using a dictionary representation:
<class 'BaseModel'> -> to_dict() -> <class 'dict'> -> <class 'BaseModel'> It’s great but it’s still not persistent: every time you launch the program, you don’t restore all objects created before… The first way you will see here is to save these objects to a file.
Writing the dictionary representation to a file won’t be relevant:
Python doesn’t know how to convert a string to a dictionary (easily) It’s not human readable Using this file with another program in Python or other language will be hard. So, you will convert the dictionary representation to a JSON string. JSON is a standard representation of a data structure. With this format, humans can read and all programming languages have a JSON reader and writer.
Now the flow of serialization-deserialization will be:
<class 'BaseModel'> -> to_dict() -> <class 'dict'> -> JSON dump -> <class 'str'> -> FILE -> <class 'str'> -> JSON load -> <class 'dict'> -> <class 'BaseModel'> Magic right?
Terms:
simple Python data structure: Dictionaries, arrays, number and string. ex: { '12': { 'numbers': [1, 2, 3], 'name': "John" } } JSON string representation: String representing a simple data structure in JSON format. ex: '{ "12": { "numbers": [1, 2, 3], "name": "John" } }' Write a class FileStorage that serializes instances to a JSON file and deserializes JSON file to instances:
models/engine/file_storage.py Private class attributes: __file_path: string - path to the JSON file (ex: file.json) __objects: dictionary - empty but will store all objects by .id (ex: to store a BaseModel object with id=12121212, the key will be BaseModel.12121212) Public instance methods: all(self): returns the dictionary __objects new(self, obj): sets in __objects the obj with key .id save(self): serializes __objects to the JSON file (path: __file_path) reload(self): deserializes the JSON file to __objects (only if the JSON file (__file_path) exists ; otherwise, do nothing. If the file doesn’t exist, no exception should be raised) Update models/init.py: to create a unique FileStorage instance for your application
import file_storage.py create the variable storage, an instance of FileStorage call reload() method on this variable Update models/base_model.py: to link your BaseModel to FileStorage by using the variable storage
import the variable storage in the method save(self): call save(self) method of storage init(self, *args, **kwargs): if it’s a new instance (not from a dictionary representation), add a call to the method new(self) on storage
- Write a program called console.py that contains the entry point of the command interpreter:
You must use the module cmd Your class definition must be: class HBNBCommand(cmd.Cmd): Your command interpreter should implement: quit and EOF to exit the program help (this action is provided by default by cmd but you should keep it updated and documented as you work through tasks) a custom prompt: (hbnb) an empty line + ENTER shouldn’t execute anything Your code should not be executed when imported Warning:
You should end your file with: if name == 'main': HBNBCommand().cmdloop() to make your program executable except when imported. Please don’t add anything around - the Checker won’t like it otherwise
- Update your command interpreter (console.py) to have these commands:
create: Creates a new instance of BaseModel, saves it (to the JSON file) and prints the id. Ex: $ create BaseModel If the class name is missing, print ** class name missing ** (ex: $ create) If the class name doesn’t exist, print ** class doesn't exist ** (ex: $ create MyModel) show: Prints the string representation of an instance based on the class name and id. Ex: $ show BaseModel 1234-1234-1234. If the class name is missing, print ** class name missing ** (ex: $ show) If the class name doesn’t exist, print ** class doesn't exist ** (ex: $ show MyModel) If the id is missing, print ** instance id missing ** (ex: $ show BaseModel) If the instance of the class name doesn’t exist for the id, print ** no instance found ** (ex: $ show BaseModel 121212) destroy: Deletes an instance based on the class name and id (save the change into the JSON file). Ex: $ destroy BaseModel 1234-1234-1234. If the class name is missing, print ** class name missing ** (ex: $ destroy) If the class name doesn’t exist, print ** class doesn't exist ** (ex:$ destroy MyModel) If the id is missing, print ** instance id missing ** (ex: $ destroy BaseModel) If the instance of the class name doesn’t exist for the id, print ** no instance found ** (ex: $ destroy BaseModel 121212) all: Prints all string representation of all instances based or not on the class name. Ex: $ all BaseModel or $ all. The printed result must be a list of strings (like the example below) If the class name doesn’t exist, print ** class doesn't exist ** (ex: $ all MyModel) update: Updates an instance based on the class name and id by adding or updating attribute (save the change into the JSON file). Ex: $ update BaseModel 1234-1234-1234 email "aibnb@mail.com". Usage: update "" Only one attribute can be updated at the time You can assume the attribute name is valid (exists for this model) The attribute value must be casted to the attribute type If the class name is missing, print ** class name missing ** (ex: $ update) If the class name doesn’t exist, print ** class doesn't exist ** (ex: $ update MyModel) If the id is missing, print ** instance id missing ** (ex: $ update BaseModel) If the instance of the class name doesn’t exist for the id, print ** no instance found ** (ex: $ update BaseModel 121212) If the attribute name is missing, print ** attribute name missing ** (ex: $ update BaseModel existing-id) If the value for the attribute name doesn’t exist, print ** value missing ** (ex: $ update BaseModel existing-id first_name) All other arguments should not be used (Ex: $ update BaseModel 1234-1234-1234 email "aibnb@mail.com" first_name "Betty" = $ update BaseModel 1234-1234-1234 email "aibnb@mail.com") id, created_at and updated_at cant’ be updated. You can assume they won’t be passed in the update command Only “simple” arguments can be updated: string, integer and float. You can assume nobody will try to update list of ids or datetime Let’s add some rules:
You can assume arguments are always in the right order Each arguments are separated by a space A string argument with a space must be between double quote The error management starts from the first argument to the last one
- Write a class User that inherits from BaseModel:
models/user.py Public class attributes: email: string - empty string password: string - empty string first_name: string - empty string last_name: string - empty string Update FileStorage to manage correctly serialization and deserialization of User.
Update your command interpreter (console.py) to allow show, create, destroy, update and all used with User.
- Write all those classes that inherit from BaseModel:
State (models/state.py): Public class attributes: name: string - empty string City (models/city.py): Public class attributes: state_id: string - empty string: it will be the State.id name: string - empty string Amenity (models/amenity.py): Public class attributes: name: string - empty string Place (models/place.py): Public class attributes: city_id: string - empty string: it will be the City.id user_id: string - empty string: it will be the User.id name: string - empty string description: string - empty string number_rooms: integer - 0 number_bathrooms: integer - 0 max_guest: integer - 0 price_by_night: integer - 0 latitude: float - 0.0 longitude: float - 0.0 amenity_ids: list of string - empty list: it will be the list of Amenity.id later Review (models/review.py): Public class attributes: place_id: string - empty string: it will be the Place.id user_id: string - empty string: it will be the User.id text: string - empty string
- Update FileStorage to manage correctly serialization and deserialization of all our new classes: Place, State, City, Amenity and Review
Update your command interpreter (console.py) to allow those actions: show, create, destroy, update and all with all classes created previously.
Enjoy your first console!
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Update your command interpreter (console.py) to retrieve all instances of a class by using: .all().
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Update your command interpreter (console.py) to retrieve the number of instances of a class: .count().
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Update your command interpreter (console.py) to retrieve an instance based on its ID: .show().
Errors management must be the same as previously.
- Update your command interpreter (console.py) to destroy an instance based on his ID: .destroy().
Errors management must be the same as previously.
- Update your command interpreter (console.py) to update an instance based on his ID: .update(, , ).
Errors management must be the same as previously.
- Update your command interpreter (console.py) to update an instance based on his ID with a dictionary: .update(, ).
Errors management must be the same as previously.
- Write all unittests for console.py, all features!
For testing the console, you should “intercept” STDOUT of it, we highly recommend you to use:
with patch('sys.stdout', new=StringIO()) as f: HBNBCommand().onecmd("help show") Otherwise, you will have to re-write the console by replacing precmd by default........