Now let's collect all the knowledge we have gained in one chapter.

Models

A Model is a class that represents a table from the database.

Model class structure

Model class should be inherited from the Model class.

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class NewModel(models.Model):

The structure of the Model class should be filled in by Field objects.

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# Example
attribute = models.IntegerField()

Note

Some fields have non-optional parameters (arguments).

Manager

Manager allows tools to manipulate the data.

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objects = models.Manager()

Command for Migrations

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python manage.py makemigrations
python manage.py migrate

Note

Try the python3 if the python doesn't work.

Instances

To work with instances, you need to use different methods.

Create

1. Create a new Model class instance.
2. Fill in all necessary attributes.
3. Submit changes using the save() method that send a query to the database.

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post = Post()

post.title = "Title"
post.text = "Text"

post.save()

Retrieve all

Return the iterable QuerySet containing database records.

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posts = Post.objects.all()

Retrieve one

Return the one database record as the Model class instance.

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post = Post.objects.get(pk=pk)

Update

1. Retrieve data.
2. Reassign attributes of the Model class instance(s).
3. Submit changes using the save() method that send a query to the database.

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post = Post.objects.get(pk=pk)

post.title = "New Title"
post.text = "New text"

post.save()

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posts = Post.objects.all()

for post in posts:
    post.title = "New Title"
    post.text = "New text"

    post.save()

URL patterns

To receive the pk from the URL address, we need to use the specific syntax: <int:pk>, where:

• int is a type of value;
• pk is the name of the argument in the view function.