Backend for survey creation application written in Flask and Flask-sqlalchemy, deployed on heroku. Contains database models for PostgreSQL and REST API endpoints for communication with frontend.

API is written with Flask-RESTful library, providing user authentication with Flask-JWT-extended. Upon user registrarion/login 2 tokens are created: access and refresh, that lasts 15 min and 30 days respectivly. Accessing token‑protected endpoints requires Authorization parameter in header of https request, with Bearer {token} value. Request parameters should be passed in header section. User logout is performed as two POST requests to /logout/access and /logout/refresh, which adds passed tokens to a blacklist.

First of all, clone project repository, and cd to it with:

git clone https://github.com/Wojak94/flaskForms
cd flaskFroms/

Environment for the application is realized with python venv package that provides virutal environment, containing isolated python packages and python binary. To create virtual environment, execute command:

python3 -m venv venv

That will create new venv/ folder. To enter created virtual environment in POSIX system with bash/zsh shell, type:

source venv/bin/activate

Personally I prefer to create alias to that command, like alias vv='source venv/bin/activate' since you'll be using it rather frequently. I also recommend to update venv bootstraped pip package with:

pip install --upgrade pip

While you are in your venv, install all packages used by the application, that are saved in requirements.txt with:

pip install -r requirements.txt

After installing requred packages you need to setup some environment variables used by the application. Generate and export $SECRET_KEY like this:

$ python3 -c 'import os; print(os.urandom(16))'
b'\x8d\x92\xa4\r\xb9.rO<5\x01\x92\x83\xab\x8f\xf4'
$ export SECRET_KEY='\x8d\x92\xa4\r\xb9.rO<5\x01\x92\x83\xab\x8f\xf4'

Generate and export $JWT_SECRET_KEY respectivly.

IMPORTANT: Do NOT copy generated keys from example, generate them by yourself!

For some quality of life improvment I also advice you to include export commands at the end of venv/bin/activate script to set that env variables automaticly as you source into the virtual environment. However, as far as I know this is not really recommended practice, but couldn't come up with better solution. Also, don't forget to clear them as they will preserve through terminal session, even if you deactivate your virtual environment. Copy that into deactivate() function in venv/bin/activate:

    if [ -n "${SECRET_KEY:-}" ] ; then
        unset SECRET_KEY
    fi
    if [ -n "${JWT_SECRET_KEY:-}" ] ; then
        unset JWT_SECRET_KEY
    fi

Now the application itself is ready to run and could be started, if you comment that line in app.py:

#app.config['SQLALCHEMY_DATABASE_URI'] = os.environ['DATABASE_URL']

However, as you might noticed we had to do that because there is no database for app to connect to. Sending any request to application will surely result with an error. Apart from that, you can run local server with flask application with:

python manage.py runserver

Default server address is http://localhost:5000/.

Depending on the system install PostgreSQL from repository/gui installer/other sources. On the Linux, you should be able to enter posgresql console with:

sudo -u postgres psql

Now as your are in psql console, create database, user and handle db privilages to him with:

create database {YOUR_DATABASE_NAME};
create user {YOUR_DB_USER_NAME} with encrypted password {YOUR_DB_PASSWORD};
grant all privileges on database {YOUR_DATABASE_NAME} to {YOUR_DB_USER_NAME};

Don't forget the semicolons at the end!
Exit psql console, with \q and enter your application virutal environment. Export $DATABASE_URL variable with following pattern:

export DATABASE_URL='postgresql://{YOUR_DB_USER_NAME}:{YOUR_DB_PASSWORD}@localhost:5432/{YOUR_DATABASE_NAME}'

Port 5432 is default for PostgreSQL, so if its different for you change it accordingly. For personal convinience apply changes to venv/bin/activate like with environment variables in the previous step. Also, if you previously commented that line in app.py now uncomment it:

app.config['SQLALCHEMY_DATABASE_URI'] = os.environ['DATABASE_URL']

At that point, Flask application should be content with all environment variables set, so the only step left is to migrate database model from application to newly created PostgreSQL database. It is done with Flask-Migrate and Alembic. Being in venv, you should be able to run:

python manage.py db upgrade

That command will apply all migrations from migrations/versions/ to PostgreSQL database. If you encounter any problems at this step, try deleting migrations/ folder and run:

python manage.py db init
python manage.py db migrate
python manage.py db upgrade

It should create new migrations/ folder, generate migration from current flask database model, and apply it to the PostgreSQL database.

If everything went as intended, congratulations! You have your own version of application running localy!

In /addsurvey endpoint passing questions as JSON in request body doesn't work in Heroku environment, only localy. It's probably associated with flushing survey instance (new_survey.flush_to_db()), before creating questions to that survey. Due to limited debugging capabilities it a free version of Heorku service I couldn't resolve that problem.

username (required)
email (required)
password (required)

• Success:

    message: "User {username} was created"
    access_token: {access_token}
    refresh_token: {refresh_token}
  

• Failure:

    message: "Something went wrong" (Probably database access or token creation error)
  

username (required)
password (required)

• Success:

    message: "Logged in as {username}"
    access_token: {access_token}
    refresh_token: {refresh_token}
  

• Failure:

    message: "User {username} doesn't exist" (cannot find user by username)
    message: "Wrong credentials" (password doesn't match specified username)
  

• Success:

    message: "Access token has been revoked"
  

• Failure:

    message: "Something went wrong" (probably database access error)
  

• Success:

    message: "Refresh token has been revoked"
  

• Failure:

    message: "Something went wrong" (probably database access error)
  

access_token: {access_token}    

name (required)
desc
duedate (required)
isactive
questions (JSON located in a request body)

• Success:

    message: "Survey {name} was created"
  

• Failure:

    message: "Something went wrong" (probably database access error)
  

idSurvey (required)    

• Success:

    questions: [
                {
                    content: {content},
                    id: {idQuestion},
                    replyContent: {replyContent},
                    type: {type}
                }, ...
             ]  
  

• Failure:

    message: "Survey doesn't exist" (if given idSurvey doesn't exist in database)
  

• Success:

    surveys: [
                {
                    name: {name},
                    isActive: {isActive},
                    dueDate: {dueDate},
                    subCount: {subCount},
                    desc: {desc}
                }, ...
             ]  
  

• Failure:

    message: "User {username} has no surveys"
  

• Success:

    surveys: [
                {
                    id: {id},
                    name: {name},
                    isActive: {isActive},
                    dueDate: {dueDate},
                    subCount: {subCount},
                    desc: {desc}
                }, ...
             ]  
  

• Failure:

    message: "There are no active surveys"
  

idSurvey (required)  
content (required)
type (required)
replyContent (JSON located in request body)

• Success:

    message: "Question was added"
  

• Failure:

    message: "Survey doesn't exist" (if given idSurvey doesn't exist in database)
    message: "User {current_username} not permited" (if id of requesting user doesn't match survey owner's id)
    message: "Something went wrong" (internal server error, 500)
  

idQuestion (required)  
reply (required)

• Success:

    message: "Reply was added"
  

• Failure:

    message: "Question doesn't exist" (if given idQuestion doesn't exist in database)
    message: "Something went wrong" (internal server error, 500)    
  

No parameters required, just plain GET/DELETE request.