15.4. Templates in Django: Template Fields

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Django templates are the real backbone of any Django application. They are responsible for structuring and manipulating the data your web application uses. In essence, a Django model is a description of a data type in your database, written in Python.

Django models are built with the help of fields, which are classes that help define the type of data that a given model attribute should have. For example, a CharField field is used to store short strings, while a TextField is used to store long strings. There are many other types of fields available, each with their own properties and uses.

Template Fields

Model fields in Django are used to create the structure of each model. They define the type of data that each attribute in a model can have. There are many different types of model controls available in Django, each with its own properties and uses.

The most common template fields include:

• CharField: A field to store short strings. You must always specify the 'max_length' argument when using this field.
• TextField: A field to store long strings. There is no need to specify a 'max_length' for this field.
• IntegerField: A field to store integer numbers.
• DecimalField: A field to store decimal numbers. You need to specify 'max_digits' and 'decimal_places' arguments when using this field.
• BooleanField: A field to store boolean values ​​(True or False).
• DateTimeField: A field to store dates and times.
• ForeignKey: A field to create a many-to-one relationship with another model.
• ManyToManyField: A field to create a many-to-many relationship with another model.

Each model field in Django can have several arguments that help define its behavior. For example, the 'null' argument allows you to specify whether a field can have a null value. The 'blank' argument allows you to specify whether a field can be empty. The 'default' argument allows you to specify a default value for a field.

Building Models with Fields

Building a Django model with fields is a simple task. First, you need to import the fields you want to use from the 'django.db.models' module. You then define a new class for your model and set the class's attributes to instances of the fields you imported.

For example, here's how you can create a simple template for a book:

from django.db import models

class Book(models.Model):
    title = models.CharField(max_length=200)
    author = models.CharField(max_length=100)
    publication_date = models.DateTimeField()
    price = models.DecimalField(max_digits=5, decimal_places=2)

In this example, the 'Book' template has four fields: 'title', 'author', 'publication_date' and 'price'. Each field is an instance of a different field class, and each has different arguments specified.

Conclusion

Django models and their fields are powerful tools that help you structure and manipulate the data in your web application. With a solid understanding of how they work, you can build robust and efficient Django applications. Remember that each model field has its own properties and uses, and that you can specify the behavior of each field with the help of arguments.

With a knowledge of how to use models and fields in Django, you are well equipped to start building your own system using Python and Django. Remember, practice makes perfect, so continue to explore and experiment with these tools to become a more effective Django developer.

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7915.5. Models in Django: Relationships between models