MVC & MTV Frameworks

Question 1

What are routes?

Answer 1

Routing is handled by a separate document that contains a list of available routes and calls to the appropriate view functions. When a request is received routing identifies the view method to be called.

Question 2

What are view functions?

Answer 2

view functions generally:

Redirect to other routes
Render specific templates
Invoke methods attached to other pieces of our app that we characterize as models

Question 3

What are models?

Answer 3

It is likely that the views file will call some model method in order to perform some operation on the database. Models should do the following:

Build database tables
Handle logic related to database operations, including validation

Question 4

What are templates?

Answer 4

a view function will either render a template or redirect. When a template is rendered Django has to parse the file looking for logic or variables you’ve inserted, interpret those, before sending a complete HTML document as a response to the client. Django templates are so similar to Flask (Jinja2) templates that you’ll hardly notice a difference.

Question 5

What does MTV stand for?

Answer 5

MTV stands for ‘model template view’, which describes the division of labor in Django.

Question 6

What does MVC stand for?

Answer 6

Models, Views and Controller
although Django’s terminology varies slightly from the usual MVC pattern, the two are close enough that Django may be considered an MVC framework. Although it is important to use the right term for each component, we can think of Django as an MVC framework.

Question 7

What does Controller mean?

Answer 7

The MVC controller is roughly equivalent to Django’s views. In both framework types this component should be in charge of outsourcing work to the models and sending the appropriately formatted data to the client. We mentioned that some other frameworks don’t outsource logic to the model. In those cases, many of our logical operations are done in the controller.

Question 8

Define Object-Relational-Mapper (ORM)

Answer 8

Django uses an Object-Relational-Mapper (ORM) to map Model definitions in the Django code to the data structure used by the underlying database. As we change our model definitions, Django tracks the changes and can create database migration scripts (in /locallibrary/catalog/migrations/) to automatically migrate the underlying data structure in the database to match the model.

Question 9

What is settings.py?

Answer 9

contains all the website settings. This is where we register any applications we create, the location of our static files, database configuration details, etc.

Question 10

What is urls.py

Answer 10

defines the site url-to-view mappings. While this could contain all the url mapping code, it is more common to delegate some of the mapping to particular applications

Question 11

What is wsgi.py

Answer 11

py is used to help your Django application communicate with the web server. You can treat this as boilerplate.

Question 12

What is manage.py?

Answer 12

The script is used to create applications, work with databases, and start the development web server.

Question 13

What is the migrations folder used for?

Answer 13

used to store “migrations” — files that allow you to automatically update your database as you modify your models.

Question 14

What is the __init__.py file?

Answer 14

an empty file created here so that Django/Python will recognise the folder as a Python Package and allow you to use its objects within other parts of the project.

Question 15

What is request.POST?

Answer 15

Data from POST request

Question 16

What is request.GET?

Answer 16

Data from GET request

Question 17

What is request.method?

Answer 17

Returns the method/HTTP verb associated with the request

Question 18

what is {% csrf_token %} used for?

Answer 18

Prevents cross-site request forgery (place it in a form on the HTML/template side of your project)

Question 19

What is request.session?

Answer 19

As request.session is just a dictionary, you can attach any key/value pairs. For example, in the views.py file, you could do:
request.session[‘name’] = request.POST[‘name’]
request.session[‘counter’] = 100
In the html file, Django lets you directly access request.session. For example to access request.session[‘name’], simply do: {{request.session.name}}

Question 20

What does the request.session[‘key’] method do?

Answer 20

This will retrieve (get) the value stored in key

Question 21

What does the request.session[‘key’] = ‘value’ do?

Answer 21

Set the value that will be stored by key

Question 22

What does del request.session[‘key’] do?

Answer 22

Deletes a session key if it exists, throws a keyError if it doesn’t. Use along with try and except since it’s better to ask for forgiveness than permission

Question 23

What does ‘key’ in request.session do?

Answer 23

Returns a boolean of whether a key is in session or not

Question 24

What does {{ request.session.name }} do?

Answer 24

Use dot notation (.) to access request.session keys from templates since square brackets ([]) aren’t allowed there