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This is based ''heavily'' on the official tutorial for the Django web programming framework.
This page should say what you should actually expect to know. It is okay that you don't understand everything you are typing in. After a lot more learning, you will be able to. The first time, though, it's okay if you don't. Will and Katie have feedback for this page.
== Writing your first Django app, part 1 ==
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=== Look at the files ===
Let’s look at files
workshop_mysite/
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=== The development server ===
Let's verify this worked.
<pre>
python manage.py runserver
</pre>
You'll see the following output on the command line:
<pre>
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Now that the server's running, visit http://127.0.0.1:8000/ with your Web browser. You'll see a "Welcome to Django" page, in pleasant, light-blue pastel. It worked!
Exit the server by pressing CONTROL-C on your keyboard.
=== Fixing security settings ===
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choice = models.CharField(max_length=200)
votes = models.IntegerField()
Save the models.py file.
All models in Django code are represented by a class that subclasses django.db.models.Model. Each model has a number of class variables, each of which represents a database field in the model.
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'polls',
)
Save the settings.py file.
Now Django knows to include the polls app.
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[<Poll: Poll object>]
Wait a minute. <Poll: Poll object> is
Use your '''text editor''' to open the polls/models.py file and adding a __unicode__() method to both Poll and Choice:
class Poll(models.Model):
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Note the addition of import datetime to reference Python's standard datetime module.
FIXME: add explanation of why we did this
Save these changes to the models.py file, and then start a new Python interactive shell by running python manage.py shell again:
>>> from polls.models import Poll, Choice
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If you want to search your database, you can do it using the '''filter''' method on the ''objects'' attribute of Poll. For example:
>>>
>>>
[<Poll: What's up?>]
>>>
1
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Right now, we have a Poll in the database, but it has no Choices. See:
>>> p = Poll.objects.get(
>>> p.choice_set.all()
[]
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<Choice: The sky>
>>> c = p.choice_set.create(choice='Just hacking again', votes=0)
>>> c
<Choice: Just hacking again>
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* Find SQLite Manager in '''Tools'''->'''SQLite Manager'''
* In the SQLite Manager menus, choose: '''Database'''->'''Connect Database'''
* Find the '''workshop_mysite/database.db''' file.
Browse your tables! This is another way of looking at the data you just created.
'''Note''': In order to find the ''database.db'' file, you might need to ask SQLite Manager to show you all files, not just the ''*.sqlite'' files.
I (the author of this tutorial) think it's really important that you be able to find this database file. So go ahead and do this step.▼
▲I (the author of this tutorial) think it's really important that you be able to find this database file. So go ahead and do this step. Browse around! Hooray.
When you're satisfied with your Poll data, you can close it.
=== Save and share our work ===
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ROOT_URLCONF = 'workshop_mysite.urls'
That means that the default URLconf
Time for an example. Edit
<pre>
from django.conf.urls.defaults import *
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(r'^polls/(\d+)/vote/$', 'polls.views.vote'),
)
</pre>
This is worth a review. When somebody requests a page from your Web site -- say, "/polls/23/", Django will load the ''urls.py'' Python module, because it's pointed to by the ROOT_URLCONF setting. It finds the variable named urlpatterns and traverses the regular expressions in order. When it finds a regular expression that matches -- r'^polls/(\d+)/$' -- it loads the function detail() from polls/views.py. Finally, it calls that detail() function like so:
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return HttpResponse("Hello, world. You're at the poll index.")
This is the simplest view possible.
Now
def detail(request, poll_id):
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return HttpResponse("You're voting on poll %s." % poll_id)
=== Write views that actually do something ===
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All Django wants is that HttpResponse. Or an exception.
Most of the Django views in the world use Django's own database API, which we covered in Tutorial 1. Let's do that, too. Here's one stab at the index() view, which displays the latest 5 poll questions in the system, separated by commas, according to publication date. Continue editing the file views.py:
from polls.models import Poll
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return HttpResponse(output)
Now go to "http://localhost:8000/polls/" in your Web browser. You should see the text of the first poll. There's a problem here, though: The page's design is hard-coded in the view. If you want to change the way the page looks, you'll have to edit this Python code. So let's use Django's template system to separate the design from Python:
from django.shortcuts import render_to_response
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</pre>
Load the page
=== Raising 404 ===
Now, let's tackle the poll detail view -- the page that displays the question for a given poll. Continue editing the ''views.py'' file. This view uses Python ''exceptions'':
from django.http import Http404
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def detail(request, poll_id):
try:
p = Poll.objects.get(
except Poll.DoesNotExist:
raise Http404
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The new concept here: The view raises the Http404 exception if a poll with the requested ID doesn't exist.
If you'd like to quickly get the above example working, just create a new template file and name it ''detail.html''. Enter in it just one line of code:
<pre>
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</pre>
Does your detail view work? Try it: http://127.0.0.1:8000/polls/1/
=== Adding more detail ===
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Method-calling happens in the {% for %} loop: poll.choice_set.all is interpreted as the Python code poll.choice_set.all(), which returns a sequence of Choice objects and is suitable for use in the {% for %} tag.
Load the new detail page in your browser: http://127.0.0.1:8000/polls/1/ The poll choices now appear.
=== Adding some style ===
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* Since we're creating a POST form (which can have the effect of modifying data), we need to worry about Cross Site Request Forgeries. Thankfully, you don't have to worry too hard, because Django comes with a very easy-to-use system for protecting against it. In short, all POST forms that are targeted at internal URLs should use the {% csrf_token %} template tag.
The {% csrf_token %} tag requires information from the request object, which is not normally accessible from within the template context. To fix this, a small adjustment needs to be made to the detail view in the "views.py" file, so that it looks like the following:
<pre>
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</pre>
The details of how this works are explained in the [http://docs.djangoproject.com/en/dev/ref/templates/api/#subclassing-context-requestcontext documentation for RequestContext].
Now, let's create a Django view that handles the submitted data and does something with it. Remember, in Tutorial 3, we created a URLconf for the polls application that includes this line:
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Okay, not quite finally. You might need to go to https://admin.alwaysdata.com/advanced/processes/ and click ''Restart my applications''.
Go to your alwaysdata site's /
* http://paulproteus.alwaysdata.com/
You should see your poll!
Create a poll! Create some choices. Find your views, and show them to the world.▼
== Part 4: Editing your polls in the Django admin interface ==
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That's the basics of the Django admin interface!
▲Create a poll! Create some choices. Find your views, and show them to the world.
== Part 4.5: Deploy again, again! ==
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