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Slide 1 [00:08 | 00:08]
------------
Title Slide
**Creating Views and Routing URLs**
Slide 2 [00:12 | 00:20]
--------------
**Learning Objectives**
In this tutorial, we will learn to;
- Use the django shell
- Create a django query
Slide 3 [00:11 | 00:31]
---------------
**System Requirements**
- Ubuntu 16.10
- Python 3.5 or higher version
- python3.4-venv
Slide 4 [00:11 | 00:42]
---------------
**Pre-requisites**
In order to follow this tutorial, you need to know;
- how to create models in django
- If not, see the relevant django tutorial on http://spoken-tutorial.org
Slide 5
------------
**What is the Django Shell**
The Django shell is a tool to help developers to
- Manipulate Django objects in a python command line environment
- Fetch and view objects in a python command line environment
Demonstration
------------
**Start the Django Shell**
In your command line environment, run the command
*python manage.py shell*
Demonstration
-------------
**Using the Django Shell**
Run the following Django Query
>>> from blog.models import Blog, Article
>>> Blog.objects.all()
>>> <QuerySet [<Blog: Blog object>]> # Output
Explanation: This django query displays all the instances of the Question model as a list.
Now let's add a new blog using the Django shell
>>> from django.utils import timezone
>>> b = Blog(name="My Second Blog", created_on=timezone.now())
>>> b.save()
Explanation:
- We create an instance of Blog and add values to it's fields (name and creation date)
- We then save the object, which means Django writes this information to the SQL table 'Blog'
Demonstration
--------------
**Filtering Entries with Django Queries**
Close and restart the django shell using the command
*python manage.py shell*
>>> from blog.models import Blog, Article
>>> b2 = Blog.objects.filter(id=2)
>>> b2
>>> <QuerySet [<Blog: Blog object>]> # Output
>>> get_b2 = Blog.objects.get(id=2)
>>> get_b2
>>> <QuerySet [<Blog: Blog object>]> # Output
Explanation: This query will give all the Blog instances with id 1, since the id is unique we get only one result. You can make sure that the id is 2 by running
>>> b2.id
>>> 2 # Output
Try sorting the Blog objects based on created_on year
>>> from django.utils import timezone
>>> current_year = timezone.now().year
>>> Question.objects.filter(created_on__year=current_year)
Explanation: This query will give all the blog instances with created_on year
Demonstration
-----------------
**Queries for related Objects**
>>> b1 = Blog.objects.get(id=1)
>>> b1.articles_set.all()
Show output
Explanation: Since every article is related to a Blog (because of the ForeignKey relationship), we can always get all Articles related to a particular blog by using the "_set" suffix
>>> a1 = Article.objects.get(id=1)
>>> b = a1.blog
>>> b.id
Explanation: You can always access the information of the Blog object through it's related Article object as shown above
You can also delete objects from shell
>>> b2.delete()
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