Develop Reference

Using Django admin as a base for backend

First sorry for my poor English.
I came from asp.net mvc. Now I use django with nanoboxio
In asp, I can create sections like below.
Create model and add it to dbcontext
Right click controller folder and create new controller with views.
Modify as you wish
For now, I know Django can create admin interface for your model. I try and happy with it. but i want to develop it.
I want to for example;
Create a post model.
Create a admin interface for it.
Copy generated admin interface controller and views to another app
Modify it
How can I do that?

Django's MVC is quite different to ASP.
Django's MVC pattern is less strict so you sort of combine the view and the controller in the views.py. However, if you want to change the Admin, the Django docs are quite nice here: docs.djangoproject.com
If you want to create a custom admin functionality the docs should give you a first idea and if you're planning to create a blog, I would advice you to use an existing plugin such as Zinnia. There, you can find the desired functionalities and modify them instead of building them from scratch.
Also, there are a couple of tutorials on how to build reusable apps and they usually include a detailed guideline how to implement admin functionalities there. Just look it up on google.
I hope that helps you!

Django: extending user model vs creating user profile model

I'm creating an app in Django and so far I have been using an extended user model like so:
class MyUser(AbstractBaseUser):
...
with all the user and profile info, but I see a lot of people creating different models for the profile and the user itself on stack overflow, using OneToOneField, although those are mostly old questions.
My question is: which is better and, if there isn't a best among them, what are the advantages for each solution?
thanks!

It depends on what you want to do -- if you're happy with the User model as it stands in the latest version of Django you should just use that -- it's easy and you'll get a lot functionality that goes along with it -- for example a pretty good permission system, and you can be sure to be compatible with all third party modules. But if you thing you'll need to expand on the User model, it's pretty straightforward how to do it. You might find that in the future you need to add more methods to your model than you expected.
The examples that you see with separate UserProfile / User model are mostly a legacy of django < 1.5, where that was the recommended way to extend the User model. There's no reason to follow that pattern any more -- it's a lot more work to have to use two models where you just want one model
**2019 Update**
If you are starting a new Django project, you should always create your own custom user model that inherits from AbstractUser, as per the Django documentation, i.e.
from django.contrib.auth.models import AbstractUser
class User(AbstractUser):
pass
even if you don't need any additional functionality. The reason for this is that for very low effort, you are making it easy to customize your user object in the future. It's very laborious to replace the built-in User object with your own after you have run the initial migrations, unless you're able to delete all of your data and migrations and start over.

I find some useful information in Django docs:
Extending Django’s default User¶
If you’re entirely happy with Django’s User model and you just want to
add some additional profile information, you could simply subclass
django.contrib.auth.models.AbstractUser and add your custom profile
fields, although we’d recommend a separate model as described in the
“Model design considerations” note of Specifying a custom User model.
AbstractUser provides the full implementation of the default User as
an abstract model.
And:
Model design considerations
Think carefully before handling information not directly related to
authentication in your custom User Model.
It may be better to store app-specific user information in a model
that has a relation with the User model. That allows each app to
specify its own user data requirements without risking conflicts with
other apps. On the other hand, queries to retrieve this related
information will involve a database join, which may have an effect on
performance.
So if I reads it correctly, it means if the fields are related to authentication, then you should consider substitute the original User model. But if it's not related, like profile fields, such birthday, or profile_image, then you might want to create a standalone app that reference the original User model.
And a good tutorial I found: http://riceball.com/d/content/django-18-tutoria-52-adding-user-profile

A ForeignKey is to create a one-to-many relationship. In other words, it will return a queryset. For example, a single car has many wheels, but one wheel isn't attached to several different cars.
A OneToOneField will create a relationship between strictly two objects. For example, the rim belongs to the front-left tire, and only that tire has that rim.
Does that make sense?

Django best practices - where should form processing logic (for creating / updating models) go

I am trying to make my Django app follow better practices than it currently does. I hear about fat models and thin controllers a lot (after putting much of my display logic in views.py initially).
Anyway, say I have a moderately complex form, for creating new objects, including foreign keys on the new objects. Assuming there are no validation errors, where should the logic for creating / linking models go? views.py after is_valid() seems the easiest place to put, but I am not sure if that is considered best practice.

In the question title you describe it as "form processing logic", but it sounds from your question text like you really mean inter-model business logic.
If it's form processing logic (cleaning, etc.), that should go on the form.
Since it sounds like you're talking about business logic, it should generally be added to the appropriate model as a model method (Django docs on model methods), then called from either the custom form logic (e.g., on save) or from the view.
Of course, where the code lives depends to a great degree on the structure of relationship between your models. Say you have an author model with a one-to-many relationship to a book model. The author model might have a method that helps you create a new book object, filling in the foreign key relation as it goes. A more complex relationship might require more view code, or at least more thought.
And yes, in general it's a good idea to try to keep your views slimmer and your models fatter.

Is Django admin difficult to customize?

I have been playing for a couple of days with Django Admin to explore it, but I am still clueless of how it can be customized in the way we need.
Every time I look for any help for the customization in the admin panel, what I find is, a bunch of articles on various communities and forums, explaining how to customize the template, the lists items, the the column views etc. But that should not be called Django Customization.
If I need to make even a small change in the User functionality or any modification to the auth module. It takes a lots of efforts even in figuring out how that can be done.
Is Django that difficult to customize or its just lack of the help available over internet for this or its me who is moving in the wrong direction ?

You are not providing enough details on what you want to achieve, so it's difficult to say how complex the task is. You might also want to consider not modifying the admin site at all and building your own views where appropriate.
However, here are some good links to get you started:
Customizing the Django Admin
Doing more with the Django admin
Extending Django's User Admin

Personally, if you want a site to look like the admin, why not pull the templates and styles and use them, build your own views for what you need. Gobs of documentation and forum help is there for that. I like the idea of customizing the admin, but honestly, I have been doing it for awhile on a project and time and time again I think to myself, if this was built in the standard MVC (or MTV) manner with free templates online, copied admin ones, or some professionally made ones, and built with the plethora of addons and my code, it would be much easier!!! And, when you decide that request/response isn't cutting it, and you want to add lots of JavaScript, you'll be glad. I know. I have had to put all sorts of JavaScript on our Admin project. Mostly because it's impossible to make the admin do what we want, so we fix it with JavaScript once it is on screen. When you find yourself writing an Ajax based system, you'll wonder why you have the admin at all.
If I could start this project over, I might not even use Django, but I probably would. I most certainly won't used the Admin.
Now, if you are building an basic CRUD type site that doesn't have style-eyed users, then Django with grappelli, and some elbow grease will get the job done. Remember, Django is a collection of Python scripts. Just override everything you can, and you'll get there, if you aren't too ambitious.

Django Admin is easy to customize if your requirements match what is customizable in Django. If you need fancy features that are not out-of-the-box functionality you either need to find a plugin that does it, or implement it yourself by subclassing the appropriate classes. Which can be difficult, and requires good understanding of the internals of Django.
So in summary: it makes it easier to setup an admin, but if you need anything special that's not out of the box: you got a steep learning curve.
Depending on your requirements you can choose to use django or not. Anything that requires a lot of functional speccing is better of implemented manually.

It's very easy . Just copy default template to project and change HTML and some variable location
Just see in this vedio
https://youtu.be/NTZfjwf4F8A

MVC and django fundamentals

Pretty new to this scene and trying to find some documentation to adopt best practices. We're building a fairly large content site which will consist of various media catalogs and I'm trying to find some comparable data / architectural models so that we can get a better idea of the approach we should use using a framework we've never made use of before. Any insight / help would be greatly appreciated!

"data / architectural models so that we can get a better idea of the approach we should use using a framework we've never made use of before"
Django imposes best practices on you. You don't have a lot of choices and can't make a lot of mistakes.
MVC (while a noble aspiration) is implemented as follows:
Data is defined in "models.py" files using the Django ORM models.
urls.py file maps URL to view function. Pick your URL's wisely.
View function does all processing, making use of models and methods in models
Presentation (via HTML templates) invoked by View function. Essentially no processing can be done in presentation, just lightweight iteration and decision-making
The model is defined for you. Just stick to what Django does naturally and you'll be happy.
Architecturally, you usually have a stack like this.
Apache does two things.
serves static content directly and immediately
hands dynamic URL to Django (via mod_python, mod_wsgi or mod_fastcgi). Django apps map URL to view functions (which access to database (via ORM/model) and display via templates.
Database used by Django view functions.
The architecture is well-defined for you. Just stick to what Django does naturally and you'll be happy.
Feel free to read the Django documentation. It's excellent; perhaps the best there is.

first, forget all MVC mantra. it's important to have a good layered structure, but MVC (as defined originally) isn't one, it was a modular structure, where each GUI module is split in these tree submodules. nothing to use on the web here.
in web development, it really pays to have a layered structure, where the most important layer is the storage/modelling one, which came to be called model layer. on top of that, you need a few other layers but they're really not anything like views and controllers in the GUI world.
the Django layers are roughly:
storage/modelling: models.py, obviously. try to put most of the 'working' concepts there. all the relationships, all the operations should be implemented here.
dispatching: mostly in urls.py. here you turn your URL scheme into code paths. think of it like a big switch() statement. try hard to have readable URLs, which map into user intentions. it will help a lot to add new functionality, or new ways to do the same things (like an AJAX UI later).
gathering: mostly the view functions, both yours and the prebuilt generic views. here you simply gather all the from the models to satisfy a user request. in surprisingly many cases, it just have to pick a single model instance, and everything else can be retrieved from relationships. for these URLs, a generic view is enough.
presentation: the templates. if the view gives you the data you need, it's simple enough to turn it into a webpage. it's here where you'll thank that the model classes have good accessors to get any kind of relevant data from any given instance.

To understand django fundementals and the django take on MVC, consult the following:
http://www.djangobook.com/
As a starting point to getting your hands dirty with ...
"...trying to find some comparable data / architectural models"
Here is a quick and dirty way to reverse engineer a database to get a models.py file,
which you can then inspect to see how django would handle it.
1.) get an er diagram that closely matches your target. For example something like this
http://www.databaseanswers.org/data_models/product_catalogs/index.htm
2.) create an sql script from the er diagram and create the database,
I suggest Postgre, as some MySQL
table type will not have forgien key constraints, but in a pinch MySQL or SQLITE
will do
3.) create and configure a django app to use that database. Then run:
python manage.py inspectdb
This will at least give you a models.py file which you can read to see how django attempts
to model it.
Note that the inspect command is intended to be a shortcut for dealing with legacy
database when developing in django, and as such is not perfect. Be sure to read the
following before attempting this:
http://docs.djangoproject.com/en/dev/ref/django-admin/#ref-django-admin