Powerful ORM of Django framework and lightweight database access of Flask

The powerful ORM of the Django framework and the lightweight database access of Flask

Introduction:
In web development, the database is an indispensable part. Database access and operations are critical to the performance and reliability of a web application. Django and Flask are two popular Python web frameworks that provide different ways of accessing databases. This article will introduce the powerful ORM (Object Relational Mapping) in the Django framework and the lightweight database access method in the Flask framework, and provide specific code examples.

1. Powerful ORM of Django framework
   Django is a full-featured web application framework, of which ORM is an important part of it. ORM is a programming technology that allows developers to operate the database in an object-oriented manner by mapping tables in the database to Python objects. Django's ORM provides rich functions and convenient syntax, which can perform complex query, insert, update and delete operations on the database.

The following is a simple Django ORM example, showing how to create a model class, insert data and query data through ORM:

from django.db import models

class User(models.Model):
    name = models.CharField(max_length=50)
    age = models.IntegerField()

# 插入数据
user1 = User(name='Alice', age=25)
user1.save()

user2 = User(name='Bob', age=30)
user2.save()

# 查询数据
users = User.objects.all()
for user in users:
    print(user.name, user.age)

In the above code, we first define a User model class, which maps to the "user" table in the database. Then, we created two User objects and saved them to the database. Finally, through the User.objects.all() method, we obtain all User objects in the database and print their names and ages.

Django's ORM also provides a wealth of query methods, such as filter(), exclude() and annotate(), etc., which can filter data according to conditions, exclude specified data, and perform aggregation operations. In addition, ORM also supports advanced functions such as transaction management, data migration and model association, which is very suitable for complex database operation requirements.

2. Flask's lightweight database access
   Compared with Django, Flask is a more lightweight web framework that does not have a built-in ORM. However, Flask provides the extension package "Flask-SQLAlchemy", which is a Flask integrated version of SQLAlchemy and provides ORM support for Flask applications.

SQLAlchemy is a Python SQL toolkit that allows developers to use SQL language for database operations in Python by providing an efficient and flexible database access interface. Flask-SQLAlchemy integrates SQLAlchemy and provides convenient database access.

The following is a simple Flask-SQLAlchemy example that shows how to use ORM for database operations:

from flask import Flask
from flask_sqlalchemy import SQLAlchemy

app = Flask(__name__)
app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:///users.db'
db = SQLAlchemy(app)

class User(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    name = db.Column(db.String(50))
    age = db.Column(db.Integer)

# 插入数据
user1 = User(name='Alice', age=25)
db.session.add(user1)
db.session.commit()

user2 = User(name='Bob', age=30)
db.session.add(user2)
db.session.commit()

# 查询数据
users = User.query.all()
for user in users:
    print(user.name, user.age)

In the above code, first we create a Flask application and configure the database connection . Then a User model class is defined, and the table and field types are specified by extending the syntax of Flask-SQLAlchemy. Next, we created two User objects and added them to the database through the db.session.add() and db.session.commit() methods, and finally User.query.all() Obtains all User objects in the database and prints their names and ages.

In addition to basic database operations, Flask-SQLAlchemy also supports complex queries, transaction management, data migration, model association and other functions, which can meet most common database needs.

Summary:
The Django framework provides rich database access functions through its powerful ORM, which is suitable for complex database operations and large-scale projects. The Flask framework provides a lightweight database access method through Flask-SQLAlchemy, which is suitable for small projects or scenarios with low database access requirements. Based on actual needs, we can choose the appropriate framework and database access method, and use the functions and syntax it provides to develop efficient and reliable Web applications.

Reference:

1. Django documentation. [Online]. Available: https://docs.djangoproject.com/
2. Flask documentation. [Online]. Available: https://flask.palletsprojects.com/
3. SQLAlchemy documentation. [Online]. Available: https://www.sqlalchemy.org/
4. Flask-SQLAlchemy documentation. [Online] ]. Available: https://flask-sqlalchemy.palletsprojects.com/

The above is the detailed content of Powerful ORM of Django framework and lightweight database access of Flask. For more information, please follow other related articles on the PHP Chinese website!