《Flask Web開發——基於Python的Web應用開發實踐》--5 數據庫--視圖函數裏面操作數據庫

 

我在學習《Flask Web開發——基於Python的Web應用開發實踐》這本書的第五章數據庫的時候，發現作者在這裏給出的代碼是不全的，因爲他只給User表中的username賦了值，而沒有考慮對Role表的name賦值，

                                            

 

因爲設計的數據庫角色和用戶是一對多的關係，用戶表中包含一個角色id外鍵。在對用戶表進行插入操作時，必須要確認一個用戶角色，否則無法插入。

這是作者的示例代碼，我們可以修改一下。

在py文件中的代碼（重點）

#額外定義一個文本框，用於接收角色名信息
class NameForm(Form):
    name = StringField('What is your name?',validators=[Required()])
    role_name = StringField('What is your role name?', validators=[Required()])
    submit = SubmitField('Submit')

#額外定義一個模型構造函數Role接收前臺傳來的數據，然後將他們添加到會話中
@app.route('/', methods=['GET', 'POST'])
def index():
    form = NameForm()
    if form.validate_on_submit():
        user = User.query.filter_by(username=form.name.data).first()
        if user is None:
            role_name = Role(name=form.role_name.data)
            user = User(username=form.name.data, role=role_name)
            db.session.add_all([user,role_name])
            session['known'] = False
        else:
            session['known'] = True
        session['name'] = form.name.data
        session['role_name']=form.role_name.data
        form.name.data = ''
        form.role_name.data = ""
        return redirect(url_for('index'))
    return render_template('index.html',
        form = form, name = session.get('name'),role_name =session.get('role_name'),
        known = session.get('known', False))

在index.html中的代碼

{% extends "base.html" %}
{% import "bootstrap/wtf.html" as wtf %}
{% block title %}Flasky{% endblock %}
{% block page_content %}
<div class="page-header">
    <h1>Hello, {% if name %}{{ name }},your role is {{role_name}}{% else %}Stranger{% endif %}!</h1>
    {% if not known %}
<p>Pleased to meet you!</p>
{% else %}
<p>Happy to see you again!</p>
{% endif %}
</div>

{{ wtf.quick_form(form) }}
{% endblock %}

效果圖

py文件完整代碼

from flask_sqlalchemy import SQLAlchemy
from flask import Flask
from flask import render_template
from flask import session,redirect,url_for
from flask_bootstrap import Bootstrap
from flask_wtf import Form
from wtforms import StringField ,SubmitField
from wtforms.validators import Required
import os

basedir = os.path.abspath(os.path.dirname(__file__))
app = Flask(__name__)
boostrap = Bootstrap(app)
app.config['SECRET_KEY'] = 'hard to guess string'
app.config['SQLALCHEMY_DATABASE_URI']=\
    'sqlite:///'+ os.path.join(basedir,'data.sqlite')
app.config['SQLALCHEMY_COMMIT_ON_TEARDOWN'] = True
app.config['SQLALCHEMY_TRACK_MODIFICATIONS'] = False
db = SQLAlchemy(app)

class NameForm(Form):
    name = StringField('What is your name?',validators=[Required()])
    role_name = StringField('What is your role name?', validators=[Required()])
    submit = SubmitField('Submit')

#返回一個具有可讀性的字符
#串表示模型，可在調試和測試時使用
class Role(db.Model):
    __tablename__ = 'roles'
    id = db.Column(db.Integer, primary_key=True)
    name = db.Column(db.String(64), unique=True)
    users = db.relationship('User',backref ='role',lazy='dynamic')
    def __repr__(self):
        return '<Role %r>' % self.name

class User(db.Model):
    __tablename__ = 'users'
    id = db.Column(db.Integer, primary_key=True)
    username = db.Column(db.String(64), unique=True, index=True)
    role_id = db.Column(db.Integer,db.ForeignKey("roles.id"))
    def __repr__(self):
        return '<User %r>' % self.username

@app.route('/', methods=['GET', 'POST'])
def index():
    form = NameForm()
    if form.validate_on_submit():
        user = User.query.filter_by(username=form.name.data).first()
        if user is None:
            role_name = Role(name=form.role_name.data)
            user = User(username=form.name.data, role=role_name)
            db.session.add_all([user,role_name])
            session['known'] = False
        else:
            session['known'] = True
        session['name'] = form.name.data
        session['role_name']=form.role_name.data
        form.name.data = ''
        form.role_name.data = ""
        return redirect(url_for('index'))
    return render_template('index.html',
        form = form, name = session.get('name'),role_name =session.get('role_name'),
        known = session.get('known', False))

if __name__=="__main__":
    app.run(host='127.0.0.1',port=8080)

參考資料：

https://www.cnblogs.com/liuzhen1995/p/8001040.html