Import: Paris.py #16

2018-paris.py-hackinscience.md

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+![](static/hkis-home.png)
+
+::: notes
+
+Remercier ceux qui nous hébergent.
+
+# HackInScience
+
+<!-- .slide: data-background="static/background.jpg" -->
+
+## Hackinscience
+
+<br/>
+
+<b>Julien Palard</b>
+
+<tt>Paris.Py #16</tt>
+
+
+## Julien Palard
+
+- Python core dev / freelance
+- CPython documentation translator (french only)
+- Python teacher/coach, at
+  - Makina Corpus
+  - Center for Research and Interdisciplinarity
+  - Sup'Internet
+  - …
+
+julien@python.org, @sizeof, https://mdk.fr
+
+
+# HackInScience
+
+Back in 2015, we started a project with the CRI of Paris Descartes: A
+one-week intensive Python class.  ![](descartes-and-cri.jpg)
+
+::: notes
+
+"The Center for Research and Interdisciplinarity" en anglais.
+
+- Ouvert à tous : élèves de l'université, chercheurs, public.
+
+
+## Pedagogy
+
+We were aiming for 50 students per week, so we had to adapt,
+we needed:
+
+- A short Python introduction (slides and a teacher).
+- Lots of exercises, sorted by difficulty.
+- A bot to correct exercises, live.
+- 2 to 3 highly available teachers in the room.
+- Short optional lessons about very specific topics.
+- Rules, teaching best practices.
+
+::: notes
+
+Rules like: never touch a student keyboard: they're here to learn.
+
+
+## 2015: Focus on content
+
+We started by focusing on exercises (needed to give a course) and the
+correction bot (needed to scale).
+
+Workflow from a student point of view:
+
+- Clone the exercise repo
+- Do exercises
+- git push
+- Receive a mail with the correction
+
+::: notes
+
+It was crude, but it worked.
+
+We automated exercises corrections (like exercises unit tests) using a
+Python script.
+
+
+## 2016: Focus on confort
+
+Antoine Angot developped a website so students do no longer needed to
+use git. Emails were no longer needed, which is nice too.
+
+::: notes
+
+Thx bro!
+
+Turns out that teaching git took a lot of time over teaching Python...
+
+And emails were easily marked as spam even with SPF and DKIM configured properly.
+
+
+## 2017: Focus on content, again
+
+The year to enhance existing parts, to rely on them, this is also the
+year of... many repositories:
+
+- One for the website
+- One for the exercises (markdown files)
+- One for our internal documentation
+- One for the correction bot
+- One for the ansible playbook
+
+::: notes
+
+Exercises had a check.py and a solution.py
+
+Internal documentation == teaching best practices.
+
+
+## 2018: Migrating to Django
+
+Jérôme Schneider started to migrate the website to Django.<br/>
+(So we could modify it more easily.)
+
+
+::: notes
+
+Thx bro :)
+A nice part was templates: the syntax was almost the same.
+
+
+# Show me the code!
+
+So what is it now? 181 lines of Python (first fully working version), it
+should fit in a few slides ;)
+
+::: notes
+
+Today it's more like 700 lines of code, mainly little tweaks
+and personalisation.
+
+
+# Django models
+
+```python
+class Exercise(models.Model):
+    title = models.CharField(max_length=255)
+    check = models.TextField()
+    solution = models.TextField()
+    wording = models.TextField()
+```
+
+::: notes
+
+Already know Django? Focus on the content.
+
+
+## Django models
+
+Helps in generating:
+
+- DB migrations;
+- Admin pages;
+- Forms;
+- Views (Using class-based views);
+- API (Using DRF);
+- Queries ("ORM" as humans say).
+
+::: notes
+
+A Django Model makes the code aware of the database structure.
+
+- Autocompletion
+- ...
+
+
+# Django view
+
+```python
+class ExerciseListView(LoginRequiredMixin, ListView):
+    model = Exercise
+    template_name = "hkis/exercises.html"
+
+```
+
+::: notes
+
+How to read this Mixin thing?
+
+Read: ExerciseListView inherite first from LoginRequiredMixin, then on ListView.
+So LoginRequiredMixin can place its method before ListView, like intercepting them.
+
+
+## Django view
+
+
+![](static/hkis-exercises.png)
+
+
+## Django view
+
+```python
+class ExerciseView(LoginRequiredMixin, DetailView):
+    model = Exercise
+    template_name = "hkis/exercise.html"
+
+    def get_context_data(self, **kwargs):
+        """Add student answers.
+        """
+        context = super().get_context_data(**kwargs)
+        context["answers"] = self.object.answers.filter(
+            user=self.request.user
+        ).order_by("-id")
+        return context
+```
+
+## Django view
+
+![](static/hkis-exercise.png)
+
+
+# Need an API now
+
+```python
+class ExerciseSerializer(serializers.HyperlinkedModelSerializer):
+    class Meta:
+        model = Exercise
+        fields = '__all__'
+
+class ExerciseViewSet(viewsets.ModelViewSet):
+    queryset = Exercise.objects.all()
+    serializer_class = ExerciseSerializer
+
+router = routers.DefaultRouter()
+router.register('exercises', ExerciseViewSet)
+```
+
+::: notes
+
+Why DRF use a router? Because there's many views in a ViewSet.
+
+## Need an API now
+
+
+![](static/hkis-api.png)
+
+::: notes
+
+A nice feature: The API replies with HTML when asked for, so
+it's browsable using a web browser.
+
+
+# Need an admin interface now
+
+```python
+from django.contrib import admin
+from website.models import Answer, Exercise
+
+admin.site.register(Answer)
+admin.site.register(Exercise)
+```
+
+## Admin interface
+
+![](static/hkis-admin.png)
+
+## Admin interface
+
+![](static/hkis-admin-markdown.png)
+
+::: notes
+
+We're using markdown to redact exercises.
+
+## Admin interface
+
+![](static/hkis-admin-check.png)
+
+::: notes
+
+This is the Python script used to check an exercise.
+
+
+# We need lives updates, now!
+
+So when a student submit an answer, he gets a correction as soon as possible.
+
+We can use `Django Channels` for this.
+
+
+## Django Channels
+
+Need first to setup some kind of high level router:
+
+```python
+application = ProtocolTypeRouter(
+    {"websocket": AuthMiddlewareStack(
+        URLRouter(website.routing.websocket_urlpatterns))}
+)
+```
+
+and
+
+```python
+websocket_urlpatterns = [
+    url(
+        r"^ws/answers/(?P<user_id>[0-9]+)/(?P<exercise_id>[0-9]+)/$",
+        consumers.AnswerConsumer,
+    )
+]
+```
+
+## Django Channels
+
+Note the `ws/` prefix, it's usefull once in production:
+
+- nginx → gunicorn, for HTTP
+- nginx → daphne, for websockets
+
+
+## Django Channels
+
+
+We're disambiguating it nginx side:
+
+```
+location /ws {
+    proxy_pass http://unix:/run/hkis-website/daphne.sock;
+    proxy_http_version 1.1;
+    proxy_set_header Upgrade $http_upgrade;
+    proxy_set_header Connection "Upgrade";
+}
+
+location / {
+    proxy_pass http://unix:/run/hkis-website/website.sock;
+    proxy_set_header Host $host;
+}
+```
+
+# The future
+
+Display exercises as a tree, with subjects like datascience, web,
+low-level, and so on as group of leafs of the tree.
+
+::: notes
+
+So one could navigate to its preferred subject.
+
+
+# Questions?
+
+- julien@python.org
+- Twitter: @sizeof
+- IRC: mdk on #python-fr (freenode)
+- https://mdk.fr
+- https://hackinscience.org