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Accessing Pyramid Settings throughout the program

I have a pyramid API which has basically three layers.
View -> validates the request and response
Controller -> Does business logic and retrieves things from the DB.
Services -> Makes calls to external third party services.
The services are a class for each external API which will have things like authentication data. This should be a class attribute as it does not change per instance. However, I cannot work out how to make it a class attribute.
Instead I extract the settings in the view request.registry.settings pass it to the controller which then passes it down in the init() for the service. This seems unnecessary.
Obviously I could hard code them in code but that's an awful idea.
Is there a better way?

Pyramid itself does not use global variables, which is what you are asking for when you ask for settings to be available in class-level or module-level attributes. For instance-level stuff, you can just pass the settings from Pyramid into the instance either from the view or from the config.
To get around this, you can always pass data into your models at config-time for your Pyramid app. For example, in your main just pull settings = config.get_settings() and pass some of them to where they need to be. As a general rule, you want to try to pass things around at config-time once, instead of from the view layer all the time.
Finally, a good way to do that without using class-level or module-level attributes is to register instances of your services with your app. pyramid_services library provides one approach to this, but the idea is basically to instantiate an instance of a service for your app, add it to your pyramid registry config.registry.foo = ... and when you do that you can pass in the settings. Later in your view code you can grab the service from there using request.registry.foo and it's already setup for you!

What are the differences between Generics, Views, Viewsets and Mixins in Django?

I am new to Django and Django-Rest. I am confused about when I should use these? what are their advantages and disadvantages? I have only seen this- http://www.cdrf.co
The only thing I know is there are a lot of ways to do 1 thing. But this is totally unclear to me.

In Django, these four terms we use frequently for different purposes in the projects. I have tried to collect and share the actual meaning with the links to details description of each term. Please check if you find these helpful.
Generic views:
“Django’s generic views... were developed as a shortcut for common usage patterns... They take certain common idioms and patterns found in view development and abstract them so that you can quickly write common views of data without having to repeat yourself.”
— Django Documentation
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Views:
A view function, or view for short, is simply a Python function that takes a Web request and returns a Web response. This response can be the HTML contents of a Web page, or a redirect, or a 404 error, or an XML document, or an image . . . or anything, really. The view itself contains whatever arbitrary logic is necessary to return that response. This code can live anywhere you want, as long as it’s on your Python path. There’s no other requirement–no “magic,” so to speak. For the sake of putting the code somewhere, the convention is to put views in a file called views.py, placed in your project or application directory.
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Viewsets:
Django REST framework allows you to combine the logic for a set of related views in a single class, called a ViewSet. In other frameworks, you may also find conceptually similar implementations named something like 'Resources' or 'Controllers'.
A ViewSet class is simply a type of class-based View, that does not provide any method handlers such as .get() or .post(), and instead provides actions such as .list() and .create().
The method handlers for a ViewSet are only bound to the corresponding actions at the point of finalizing the view, using the .as_view() method.
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Mixins:
The mixin classes provide the actions that are used to provide the basic view behavior. Note that the mixin classes provide action methods rather than defining the handler methods, such as .get() and .post(), directly. This allows for more flexible composition of behavior.
The mixin classes can be imported from rest_framework.mixins.
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Is it possible to call different function of class based views through different actions in template

I am new to django and i ahve gone through all the docs of django. right now if we give some link in template and defined that link in urls.py i.e which view is going to handle that link. like this url(r'^dashboard/gift/$', login_required(CouponPageView.as_view())),
But i have this little doubt can i call different function of a view on clicking different links present in template.

The idea behind a class-based view is not to serve multiple resources (the targets of the links in your template). The idea is that the class-based view implements methods for the various HTTP methods (i.e. get, post, put, delete, head).
So you can server an HTTP GET of a certain URI using the SomeView.get() method, or you can handle a POST to the same resource from the post() method in the same SomeView class. This is helpful to support object oriented code, as the different methods on the object will typically share some resources.
If you want to handle different URL's, write different View classes. If their functionality is similar, use inheritance to prevent code duplication. If their functionality is almost identical, use parameters in the urlpattern.
I think you need to study the URL dispatcher a little more: https://docs.djangoproject.com/en/dev/topics/http/urls/

requests using django session table

I have an application that uses the requests library to make calls to a web service. On django, I use a table to keep sessions using the standard django_session library.
I've noticed that I have a new record in the database for every time the requests library fires off a call. I find this quite bizarre, since I'm not using request sessions (explicitly) and most of my calls are single GET calls that shouldn't need any kind of persistance.
Has anybody else had this problem?

django.contrib.sessions.middleware.SessionMiddleware will create a new session for each request.
If you want to disable this behavior, consider replacing django.contrib.sessions.middleware.SessionMiddleware with a custom middleware that extends django.contrib.sessions.middleware.SessionMiddleware but prevents sessions from being created in instances where you don't want them.
This answer provides an example of how to do so. It parses request.path_info to determine whether a session should be created, but you could use a number of different techniques, such as adding a custom header to your request, including a post variable, etc.

Turns out I had this setting turned on
SESSION_SAVE_EVERY_REQUEST=True
When I started with sessions I wanted to be safe to make sure nothing falls through the cracks. Turns out this was then writing empty session information to the db.

Python SESSION (like php) class

is there any class to handle a SESSION (like php) in Python? not in django, but I want to use it with PyQt
thank you

The short answer is that there is no $SESSION variable in Python.
Python tends not to put things in global scope like PHP. Therefore, if you are accessing a user's session id, it will probably be accessed via dot notation module_name.ClassName.session. If you would like to create a PyQt app that acts as a webserver, you could probably adapt a web framework's implementation.
Others' responses to similar queries suggest implementing sessions via a simple database[1]. You could try assigning unique ids with uuid, and storing them with tools like sqlite3 or pickle.
[1] http://ubuntuforums.org/showthread.php?t=859645

Theres a session class with mod_python for apache, that can be a good starting point for making our own class. The class is not very dependent on apache to work.
http://www.modpython.org/