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Huge Django project

I have a new job and a huge django project (15 apps, more than 30 loc). It's pretty hard to understand it's architecture from scratch. Are there any techniques to simplify my work in the beginning? sometimes it's even hard to understand where to find a form or a view that I need... thnx in advance.

When I come to this kind of problem I open up a notebook and answer the following:
1. Infrastructure
Server configuration, OS etc
Check out the database type (mysql, postgres, nosql)
External APIS (e.g Facebook Connect)
2. Backend
Write a simple description
Write its input/output from user (try to be thorough; which fields are required and which aren't)
Write its FK and its relation to any other apps (and why)
List down each plugin the app is using. And for what purpose. For example in rails I'd write: 'gem will_paginate - To display guestbook app results on several pages'
3. Frontend
Check out the JS framework
Check the main stylesheet files (for the template)
The main html/haml (etc) files for creating a new template based page.
When you are done doing that. I think you are much more prepared and able go deeper developing/debugging the app. Good luck.

Use this http://packages.python.org/django-extensions/graph_models.html
to generate the Relationship diagrams from the models so that you can visually see how the models are related to each other. This will give you nice idea about the app

1) Try to install the site from scratch. You will find what external apps are needed for the site to run.
2) Reverse engineer. Browse through the site and try to find out what you have to do to change something to that page. Start with the url, look up in urls.py, read the view, check the model. Are there any hints to other processes?
3) Try to write down everything you don't understand, and document the answers for future reference.

I would clone the project so you can mess up endlessly.
Then I would start to reduce the code. "What happens if if just remove this function here?
Also get django debug toolbar:
https://github.com/django-debug-toolbar/django-debug-toolbar
A good terminal debugger is also golden, there are many out there, here is an example:
https://github.com/tomchristie/django-pdb
This allow you to halt the code and even inject and mutate parameters in runtime. Just like GDB in C.

If you use FireFox you can install FireBug on it and when you for example submit ajax form you can see at which url send you request after what you can easily find controller which work with this form data. At chrome this utility embedded by default and call by F12 key.

Django - Managing page content in Django Admin

I'm new to working with Django and am developing for a client who wants to be able to change page content in the Django Admin. They need to be able to change the html of the index page without editing the files on the server.
I know about flatfiles but I'm not sure that's completely what I'm after as I can't display stuff such as Django forms for example.
EDIT: Kind of like how a CMS works but without the users/group stuff and be able to use Django View modules such as forms.
Any advice?
Thanks

Honestly, the scope of what you're looking for is too huge to cover in this format. There's a number of ways this could be done, but they're all going to require some work and customization based on the client's needs.
Flatpages could work if you allow HTML content and make sure the content is rendered as "safe" in the template. This really only covers the "content" area of the site, though. It wouldn't be wise to use flatpages for an entire site template, including header, sidebar, footer, etc.
You could create editable areas. So, you actually create models for things like headers, sidebars, footers, and modules within those areas, and then just pull them into the template as needed. Then, the client is only editing pieces of the template instead of responsible for the whole HTML document.
Forms are going to be a challenge, because they require backend-processing that requires a connected view. The client won't be able to just arbitrarily drop in some form code and have a form. But, you could use a third-party service form forms and just embed them in the available content regions. Or, there's a couple of django apps that try to implement a type of "form builder" in the admin. That might somehow let the client add a form via something like the shortcodes used in Wordpress, but you'd likely have to lay down some infrastructure to make that work.
At a certain point, stuff like this reaches a point of diminishing returns, though. The only way to allow total customization of the template is to drop down into the actual physical file and make changes there. You can make certain things easier for the client, but ultimately, they either need to scale back their customization needs or deal with the fact that they'll have to work with the filesystem.

I don't believe that is possible at this time. Of course you can edit your models but templates, I think not.

I would find out how much they need to change? If they plan a complete redesign every week then you're still looking for an answer. If they just need a dynamic front page then you can split it up into variables and let them edit sections of html. Much safer and less prone to breaking the html.

How to see current context when debugging template errors?

I am getting a template error during rendering, which I think would be easy to fix if I could just see what's in the context that is passed into the template that is being rendered. Django's debug error page provides a lot of information, but I'm not seeing my context anywhere. Am I missing something? Also, I am using Django-debug-toolbar, but that only seems to come up if the page successfully renders. Not being able to see the contents of the context that is passed to the template makes debugging some types of template errors hard! What do I need to do to be able to see it in this scenario? (Note that I'm not asking for a fix to my specific error, which is why I'm not providing more information about it).

From the comments:
I think you need to walk up the stacktrace (in the django debug page) to actually see your context variables. I don't understand your problem exactly. If I have a template error I can inspect my context somewhere in the traceback.
Yes, setting a "breakpoint" in django can sometimes mean just inserting a non-defined variable at the point you want to inspect. The last entry in the traceback is usually the one for this variable. It will give you all context details in the traceback of the debug page.

The easiest way to do this is with the Django Debug Toolbar. it will give you a popup tab on the right hand side of your screen that you can use to inspect various things about the current page's request. Things like SQL statements, versions, logging, and all the templates that were used to render the page, and the context available to each of them.

Add a debugging page to a Django project?

I'm supplying a Django project to a client, who has requested a 'debugging' page that will show useful information.
[UPDATE for clarity: We'd like this page so we can use it for debugging in future: the clients are not very technical and I won't have direct access to their servers. In the event of future issues, it would be very useful if I could check out this page without asking them to edit the Debug setting or do any other server-side fiddling.]
The project will be running in production, so I can't set DEBUG=True.
What I would like is a page similar to the Django debugging page but without any sensitive information in.
I guess I can simply write my own, but does anyone have any ideas? Anything standard in Django I could use?
Thanks!

Googling 'standard Django debugging page'
Isn't as effective as reading the Django source itself.
Look in base.py for code like this
from django.views import debug
That will provide you some hints as to how they do it.
Then you can look at django/views/debug.py for the "technical_404_response" view function. You can use this function in your code, also.

You can use Django Debug Toolbar and enable it only for choosen IPs

What to do after starting simple_server?

For some quick background, I'm an XHTML/CSS guy with some basic PHP knowledge. I'm trying to dip my feet into the Python pool, and so far understand how to start simple_server and access a simple Hello World return in the same .py file. This is the extent of what I understand though, heh.
How do I integrate the simple_server and your basic XHTML/CSS files? I want to start the server and automagically call, for instance, index.py (does it need to be .py?). Obviously within the index file I would have my markup and stylesheet and I would operate it like a normal site at that point.
My eventual goal is to get a basic message board going (post, edit, delete, user sessions). I realize I'll need access to a database, and I know my way around MySQL enough to not have to worry about those portions.
Thanks for the help.
EDIT: Allow me to clarify my goal, as I have been told Python does a LOT more than PHP. My goal is to begin building simple web applications into my pre-existing static XHTML pages. Obviously with PHP, you simply make sure its installed on your server and you start writing the code. I'd like to know how different Python is in that sense, and what I have to do to, say, write a basic message board in Python.

The other answers give good recommendations for what you probably want to do towards your "eventual goal", but, if you first want to persist with wsgiref.simple_server for an instructive while, you can do that too. WSGI is the crucial "glue" between web servers (not just the simple one in wsgiref of course -- real ones, too, such as Apache or Nginx [both with respective modules called mod_wsgi] as well as, for example, Google App Engine -- that one offers WSGI, too, as its fundamental API) and web applications (and frameworks that make it easier to write such applications).
Everybody's recommending various frameworks to you, but understanding WSGI can't hurt (since it will underlie whatever framework you eventually choose). And for the purpose of such understanding wsgiref.simple_server will serve you for a while longer, if you wish.
Essentially, what you want to do is write a WSGI app -- a function or class that takes two parameters (an "enviroment" dictionary, and a "start response" callable that it must call back with status and headers before returning the response's body). Your "WSGI app" can open your index.py or whatever else it wants to prep the status, headers and body it returns.
There's much more to WSGI (the middleware concept is particularly powerful), though of course you don't have to understand it very deeply -- only as deeply as you care to! See wsgi.org for tutorials &c. Gardner's two-part article, I think, is especially interesting.
Once (and if that's your choice) you understand WSGI, you can better decide whether you want it all hidden in a higher level framework such as Django (so you can focus on application-level issues instead) or use a very light and modular toolbox of WSGI utilities such as Werkzeug -- or anything in-between!-)

I would recommend Django.

"Obviously with PHP, you simply make sure its installed on your server and you start writing the code."
Not true with Python. Python is just a language, not an Apache plug-in like PHP.
Generally, you can use something like mod_wsgi to create a Python plug-in for Apache. What you find is that web page processing involves a lot of steps, none of which are part of the Python language.
You must use either extension libraries or a framework to process web requests in Python. [At this point, some PHP folks ask why Python is so popular. And the reason is because you have choices of which library or framework to use.]
PHP parses the request and allows you to embed code in the resulting page.
Python frameworks -- generally -- do not work this way. Most Python frameworks break the operation down into several steps.
Parsing the URL and locating an appropriate piece of code.
Running the code to get a result data objects.
Interpolating the resulting data objects into HTML templates.
"My goal is to begin building simple web applications into my pre-existing static XHTML pages."
Let's look at how you'd do this in Django.
Create a Django project.
Create a Django app.
Transform your XTHML pages into Django templates. Pull out the dynamic content and put in {{ somevariable }} markers. Depending on what the dynamic content is, this can be simple or rather complex.
Define URL to View function mappings in your urls.py file.
Define view functions in your views.py file. These view functions create the dynamic content that goes in the template, and which template to render.
At that point, you should be able to start the server, start a browser, pick a URL and see your template rendered.
"write a basic message board in Python."
Let's look at how you'd do this in Django.
Create a Django project.
Create a Django app.
Define your data model in models.py
Write unit tests in tests.py. Test your model's methods to be sure they all work properly.
Play with the built-in admin pages.
Create Django templates.
Define URL to View function mappings in your urls.py file.
Define view functions in your views.py file. These view functions create the dynamic content that goes in the template, and which template to render.

Take a look at CherryPy. It's a nice http framework.

It depends on what you want to achieve,
a) do you want to just write a web application without worrying too much abt what goes in the background, how request are being handled, or templates being rendered than go for a goo webframework, there are many choices simple http server is NOT one of them. e.g. use django, turbogears, webpy, cheerpy, pylons etc etc
see http://wiki.python.org/moin/WebFrameworks for full list
b) if you want to develope a simple web framework from start so that you understand internals and improve you knowledge of python, then I will suggest use simple http server
see
how can you create a URL scheme so that URLs are dispatched to correct python function,
see how can you render a html
template e.g. containing place
holder variables $title etc which
you can convert to string using
string.Template
b) would be difficult but interesting exercise to do, a) will get you started and you may be writing web apps in couple of days