First steps to UniSport-O-Mat

Some notes

To ensure a clean development and production environment, we will use virtualenv. If you have not installed or used it yet, please refer to the official documentation.

Starting virtualenv

First create a new folder, in which you want to give this project a new home. Then, create a new virtualenv via this command in your terminal

virtualenv -p python3 .

You'll see a few new folders and a config file for your virtualenv. You can start the new environment via this command in your terminal, depending on your OS.

Linux/MacOS:

source bin/activate

Windows

Scripts/activate

If done correctly, you'll see the name of the virtual environment printed at the beginning of your command promt, eg. in bash:

(unisport-o-mat) 18:57:55 [foo@bar unisport-o-mat]$

Cloning the project

To clone the project via git, please enter one of these commands via your terminal, depending on your preferred way to authenticate. Via HTTPS:

git clone https://git.imp.fu-berlin.de/swp-unisport/team-warumkeinrust/unisport-o-mat.git

Via ssh:

git clone git@git.imp.fu-berlin.de:swp-unisport/team-warumkeinrust/unisport-o-mat.git

Installing dependencies

You can verify that no python libraries are installed in your virtualenv, if you enter the following command via terminal. It should not return any modules right now.

python -m pip freeze

All required dependency, such as Django, will be installed via pip and a text file, such as requirements.txt. First, switch the current directory via cd into the cloned folder. Then, install the dependencies all at once via this command in your terminal.

python -m pip install -r requirements.txt

Starting the django web server

To start the web server, change the directory via cd in the project folder. Here you will find the manage.py script, which will be used to start commands depending on the Django framework. Start the web server via this command in your terminal.

python manage.py runserver

If successful, you can now see the running server in your browser at http://127.0.0.1:8000.

Populate the database with test data

To populate the database with some test data run

python manage.py seed_db [-y] [--seed SEED] [--no-superuser]

All the existing data from your database will be lost!
Per default a super user called "admin" will be created for development. You will be prompted for a password.
Run python manage.py seed_db --help for more information.

Use the django admin interface to view and edit data during development

If you started the server as described above, you can access the django admin interface on localhost:8000/admin.
If you seeded the database you can login with username: "admin" and the password you specified.

Internationalization and how to use it

At the current time, the backend uses django-modeltranslation to handle translations of Strings in the models Question, CallToMove, KnowledgeSnack. The list of available languages is defined in settings.py, and the translatable fields are defined in translation.py. Right now, the two languages de and en are enabled, with de translations needing to be filled out.

Django internally keeps track of the active language, which decides on the language strings that object.text returns. If you want to force a certain language, object.text_de can be used.

"django.middleware.locale.LocaleMiddleware" has been added as a Middleware. This allows Django to recognize the locale of the requesting Browser and automatically sets the language to that locale. This means that both the Django Admin Panel and our own API choose the Strings depending on the GET request. It is yet to be determined whether React can change the locale in the requests, but if that were the case, this feature would potentially ease the implementation of Serializers for the User-Frontend.

Instead of relying on the Locale given by the Requests, one can also manually change the active language. This example demonstrates how:

from django.utils.translation import get_language, activate

cur_language = get_language() # Returns current active language

activate("de") # Selects German as active language

print(object.text) # Prints German Translation

activate("en") # Selects English as active language

print(object.text) # Prints English Translation

activate(cur_language) # Resets active language to the one before manual activations

This might be particularly useful for entering data from the Admin Frontend into the database, or choosing the language for the User Frontend if the Browser Locale cannot be used.

Pagination in Views

Every list that needs to be paginated needs a paginator. Here, the Paginator object is created in the GET call. The Queryset which is supposed to be paginated needs to be run through the function:

new_queryset = paginator.paginate_queryset(complete_queryset, request)

The new_queryset is a List, not a Manager, so it can be directly iterated upon. After the data has been worked on and run through the Serializer as normal, instead of returning Result(data), the paginator needs to be used again so it can add its page metadata:

return paginator.get_paginated_response(serializer.data)

This function already returns a fully valid Response, so it can be directly returned.