Django model-猿码集

Django Model

1. Introduction

In Django, models are used to define the structure and behavior of data. Models represent database tables and provide a convenient API to interact with the data stored in those tables. This article will provide a detailed explanation of Django models and their usage.

2. Creating Models

Django models are usually created in a file called models.py within an app. Each model is represented by a Python class that inherits from the django.db.models.Model base class.


from django.db import models
class MyModel(models.Model):
    field1 = models.CharField(max_length=100)
    field2 = models.IntegerField()

In the above example, we have created a model named MyModel with two fields: field1 of type CharField and field2 of type IntegerField.

3. Field Types

Django provides a wide range of field types that can be used in models to represent different types of data. Some commonly used types are:

3.1 CharField

The CharField type is used to store a string of characters.

title = models.CharField(max_length=100)

3.2 IntegerField

The IntegerField type is used to store integer values.

count = models.IntegerField()

3.3 BooleanField

The BooleanField type is used to store boolean values (True or False).

is_active = models.BooleanField()

There are many more field types available in Django, which can be used according to the requirements of the project.

4. Field Options

Field options are used to define various constraints and behaviors of a field. Some commonly used options are:

4.1 max_length

The max_length option is used to specify the maximum length of a string field.

name = models.CharField(max_length=50)

4.2 default

The default option is used to set a default value for a field.

is_active = models.BooleanField(default=False)

These are just a few examples of field options. Django provides a wide range of options to customize the behavior of fields.

5. Querying Models

Once models are created, we can query the data stored in the corresponding database table. Django provides a powerful querying API, which allows us to retrieve, filter, and manipulate data easily.

5.1 Retrieving All Objects

We can retrieve all objects of a model using the objects.all() method.

all_objects = MyModel.objects.all()

5.2 Filtering Objects

We can filter objects based on specific conditions using the objects.filter() method.

filtered_objects = MyModel.objects.filter(field1='value')

These are just basic examples of querying models. Django provides many other methods to perform complex queries like exclude(), get(), order_by(), etc.

6. Conclusion

In this article, we have explored the basics of Django models. We have learned how to create models, define fields, and perform queries on the models. Understanding models is essential for building a Django application as they form the backbone of the data structure. Django's model system provides a robust and easy-to-use interface for working with databases.

Django model