srcminiFlask SQLAlchemy是一个ORM工具, 用于建立对象和关系数据库表之间的关系。
两者之间的映射很重要, 因为python能够以对象的形式存储数据, 而数据库则以关系表(即行和列的集合)的形式存储数据。
对象关系映射是一种将python对象存储到数据库表中而无需编写原始SQL查询的技术。
在本教程的这一部分中, 我们将使用flask-sqlalchemy ORM技术创建一个小型Web应用程序。
安装flask-sqlalchemy
要使用flask ORM技术创建Web应用程序, 我们必须使用pip安装程序安装flask-sqlalchemy。
$ pip install flask-sqlalchemy要确认安装, 请尝试在python shell上导入模块。如果导入成功, 则安装成功。
$ import flask_sqlalchemy使用flask-sqlalchemy创建小型Web应用程序
在本教程的这一部分中, 我们将使用ORM SQLAlchemy在python中创建一个CRUD应用程序。
例子
add.html
<!DOCTYPE html>
<html>
<body>
<h3>Add new Employee</h3>
<hr/>
{%- for category, message in get_flashed_messages(with_categories = true) %}
<div class = "alert alert-danger">
{{ message }}
</div>
{%- endfor %}
<form action = "{{ request.path }}" method = "post">
<label for = "name">Name</label><br>
<input type = "text" name = "name" placeholder = "Name" /><br>
<label for = "salary">Salary</label><br>
<input type = "text" name = "salary" placeholder = "salary" /><br>
<label for = "age">Age</label><br>
<textarea name = "age" placeholder = "age"></textarea><br>
<label for = "PIN">Pin</label><br>
<input type = "text" name = "pin" placeholder = "pin" /><br>
<input type = "submit" value = "Submit" />
</form>
</body>
</html>list_employees.html
<!DOCTYPE html>
<html lang = "en">
<head><title>Home</title></head>
<body>
<h3>
<a href = "{{ url_for('list_employees') }}">Employee Management System</a>
</h3>
<hr/>
{%- for message in get_flashed_messages() %}
{{ message }}
{%- endfor %}
<h3>Employees List</h3>
<table border="2" padding = "5">
<thead>
<tr>
<th>Name</th>
<th>Salary</th>
<th>Age</th>
<th>Pin</th>
</tr>
</thead>
<tbody>
{% for employee in Employees %}
<tr>
<td>{{ employee.name }}</td>
<td>{{ employee.salary }}</td>
<td>{{ employee.age }}</td>
<td>{{ employee.pin }}</td>
</tr>
{% endfor %}
</tbody>
</table>
<br><br>
<a href="{{ url_for('addEmployee') }}">Add New Employee</a>
</body>
</html>app.py
from flask import Flask, request, flash, url_for, redirect, render_template
from flask_sqlalchemy import SQLAlchemy
app = Flask(__name__)
app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:///employees.sqlite3'
app.config['SECRET_KEY'] = "secret key"
db = SQLAlchemy(app)
class Employees(db.Model):
id = db.Column('employee_id', db.Integer, primary_key = True)
name = db.Column(db.String(100))
salary = db.Column(db.Float(50))
age = db.Column(db.String(200))
pin = db.Column(db.String(10))
def __init__(self, name, salary, age, pin):
self.name = name
self.salary = salary
self.age = age
self.pin = pin
@app.route('/')
def list_employees():
return render_template('list_employees.html', Employees = Employees.query.all() )
@app.route('/add', methods = ['GET', 'POST'])
def addEmployee():
if request.method == 'POST':
if not request.form['name'] or not request.form['salary'] or not request.form['age']:
flash('Please enter all the fields', 'error')
else:
employee = Employees(request.form['name'], request.form['salary'], request.form['age'], request.form['pin'])
db.session.add(employee)
db.session.commit()
flash('Record was successfully added')
return redirect(url_for('list_employees'))
return render_template('add.html')
if __name__ == '__main__':
db.create_all()
app.run(debug = True)输出
单击链接”添加新员工”以将新员工添加到数据库。
单击提交, 我们将在主页列表中看到新添加的员工。
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