The questions I've had during my learning process.

Id Question Solved at
1 How do you install? Solved
2 How do you start developing? Solved
3 How do you make graphics with Django? Solved
4 Django uses some kind of structure to tell the application where to look for links. How does this hierarchy work? What is actually put into the different files? Solved
5 What is the most basic way to add the url:s to Solved
6 What is the " '^ " thing that can be seen in the URLpatterns? Solved
7 What is the $ sign in the URLpatterns? Solved
8 If I want to embed an iframe to the app can I do it straight into the HTML? Pending
9 Are all of the URLpatterns always put into the file? Pending
10 Is it difficult to change to the production server? Pending
11 How do I really get an external CSS sheet working? Pending
12 How do I connect a new app that I've created under the project folder to the project? Pending
13 What's the development process if I want to create a new website with apps? Something discovered
14 How do you cross query models? For example, If I have a blog app and a books app, how can I show related blog posts in my books app? Pending
15 How do I take the admin interface into use? Solved
16 How do I alter the models I already have? Pending
17 How do I customize what is shown and can be edited in the admin interface? Solved
18 When I want to start developing after some time, how do I start the server and check the page etc? Pending

Friday, 15 May 2009

The Django Structure - from urlconf to view, to model...

This is a continuation of the Capturing Learning Django project.

Just some more explanation for question nr. 4... I'm coming back to these questions since I want to document the process of learning. So even though I'm going back to some of the questions, capturing the progress is also important... However, I'll only post the new stuff from now on.

4. Django uses some kind of structure to tell the application where to look for links. How does this hierarchy work? What is actually put into the different files?

Got some more answers to this issue. I'll now try to explain what happens in my app. A more illustrative picture is attached below.

I have a blog, under /djangoblog/blog. So I input in my browser. Then:
  1. A URL call matches a URL in the file which is in /djangoblog/
  2. In the file, I have this line: (r'^blog/', include('')), which redirects to /djangoblog/
  3. In there, one of the lines is
    • (r'^$','archive_index', dict(info_dict, template_name='blog/list.html')),
    • This line fits the url pattern ...8000/blog ... because of ^$ which matches an empty string after the /blog.
    • This line redirects to blog/list.html
  4. Then my template blog/list.html takes over. It resides in djangoblog/templates/blog/list.html. I think Django can find it automatically from there since I've configured the templates in the
    • This file starts with {% extends 'base.html' %}, and thus first loads my base.html template, which is found in djangoblog/templates/base.html
    • This list.html file then says to the browser what is shown. It's an html-file! The special thing is is that it's also full of Django/python.
  5. The Django/Python calls, such as:

    {{ object.pub_date|date:"D d M Y" }}

    , then call up the methods from the djangoblog/blog/
  6. That's it. The model is the actual Python code that says what the page shows.

It seems the explanation above is missing views. So with views, the urlconf actually calls a function in the file:

1. In my urlconf, I have for example:

(r'^polls/(?P<poll_id\d+)/$, 'learness2.polls.views.detail'),

That means that for all url's that follow that pattern, the detail function in the file will be revoked. If for example the url that is called is 'polls/2/', the function is called like this: detail (request=, poll_id='2')

This is the picture that I found about the issue in, by designer and Coder Jeff Croft:

However, according to my experience, you could also draw it like this, to visualize how the URL request moves in the Django app:

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