Now that you have updated models.py and run migrations we can turn to adding and retrieving data from the database and serving it to a dynamic HTML template.

In your project directory, type (myenv) $ python manage.py shell.

from my_app.models import Fish
all_fish = Fish.objects.all()

This equivalent to a query of all values in a table:

SELECT * from my_app_fish;

Note that you have the option to send raw queries, it’s just a lot more complicated that way: all_fish = Fish.objects.raw('SELECT * from my_app_fish;')

Our all_fish variable is a Django queryset object. You can find the documentation on them here: queryset objects.

The most common ways that you’ll request data from the data base is either with all() or

• Model.objects.filter() with a field and value. Fish.objects.filter(type='trout'), for example, will return all the trout records.

• Model.objects.get() will get a single record. Fish.objects.filter(id=1)

When adding records to the database, we very often rely on the update_or_create() function. This will check if an existing record exists, in which case it updates the existing record. Otherwise it creates a new record.

data = {'fish':{'name':'Sammy','type':'shark'}}
name = data['fish']['name']
type = data['fish']['type']
Fish.objects.update_or_create(name=name, type=type)  

Q objects