flask内容之数据库的管理

 #! /usr/bin/env python
 # *-* coding: utf-8 *-*

 from flask import Flask, flash, redirect
 from flask import url_for
 from flask import request
 from flask_wtf import FlaskForm
 from wtforms import StringField, SubmitField
 from wtforms.validators import InputRequired
 from flask import render_template
 from flask_sqlalchemy import SQLAlchemy

 app = Flask(__name__)

 # 配置数据库连接地址
 app.config["SQLALCHEMY_DATABASE_URI"] = "mysql://root:qw123666@localhost/test?charset=utf8"
 # 是否追踪数据库的修改
 app.config['SQLALCHEMY_TRACK_MODIFICATIONS'] = False
 app.config["SQLALCHEMY_ECHO"] = False
 app.secret_key = ""

 # 初始化 SQLAlchemy 对象
 db = SQLAlchemy(app)

 # 定义模型类-作者
 class Author(db.Model):
     __tablename__ = 'author'
     id = db.Column(db.Integer, primary_key=True)
     name = db.Column(db.String(32), unique=True)
     book = db.relationship('Book', backref='author')

     # def __repr__(self):
     #     return 'Author:%s' % self.name

 # 定义模型类-书名
 class Book(db.Model):
     __tablename__ = 'books'
     id = db.Column(db.Integer, primary_key=True)
     name = db.Column(db.String(32))
     author_id = db.Column(db.Integer, db.ForeignKey(Author.id))

     # def __str__(self):
     #     return 'Book:%s,%s' % (self.info, self.lead)

 class AddBookForm(FlaskForm):
     author = StringField("作者", validators=[InputRequired("请输入作者名")])
     book = StringField("书名", validators=[InputRequired("请输入书名")])
     submit = SubmitField("添加")

 @app.route("/index", methods=["get", "post"])
 def index():
     # 获取所有的作者
     bookform = AddBookForm()
     if request.method == "POST":
         # 取值
         if bookform.is_submitted():
             author_name = bookform.author.data
             book_name = bookform.book.data
             #     查指定作者的名字是否存在
             author = Author.query.filter(Author.name == author_name).first()
             if not author:
                 try:
                     # 增加作者
                     author_obj = Author(name=author_name)
                     db.session.add(author_obj)
                     db.session.commit()
                     # 增加书名
                     book_obj = Book(name=book_name, author_id=author_obj.id)
                     db.session.add(book_obj)
                     db.session.commit()
                 except Exception as e:
                     db.session.rollback()
                     flash("添加失败")
             else:
                 try:
                     book_obj = Book(name=book_name, author_id=author.id)
                     db.session.add(book_obj)
                     db.session.commit()
                 except Exception as e:
                     db.session.rollback()
                     flash("添加失败")
         # 往数据开中写入值
         authors = Author.query.all()
         return render_template("index.html", authors=authors, form=bookform)

     authors = Author.query.all()
     return render_template("index.html", authors=authors, form=bookform)

 @app.route("/delete_author/<author_id>")
 def delete_author(author_id):
     author_obj = Author.query.get(author_id)
     if author_obj:
         try:
             Book.query.filter(Book.author_id == author_id).delete()
             db.session.delete(author_obj)
             db.session.commit()
         except Exception as e:
             print("删除作者名失败")
             db.session.rollback()
     else:
         flash("没有这个作者")
     authors = Author.query.all()
     bookform = AddBookForm()

     return redirect(url_for('index'))

 @app.route("/delete_book/<book_id>")
 def delete_book(book_id):
     try:
         # 书的对象
         book_obj = Book.query.get(book_id)
         print(book_obj)
         # 书的作者的id
         author_id = book_obj.author.id
         # author_id = book_obj.Author.id
         print(author_id)
         if book_obj:
             db.session.delete(book_obj)
             author_count = len(book_obj.author.book)
             if author_count == 0:
                 # author_obj = Author.query.get(author_id)
                 author_objs = Author.query.filter(Author.id == author_id).all()
                 print("author_obj", author_objs)
                 for author_obj in author_objs:
                     db.session.delete(author_obj)

     except Exception as e:
         print("没有这本书")
     db.session.commit()

     authors = Author.query.all()
     bookform = AddBookForm()
     return render_template("index.html", authors=authors, form=bookform)

 if __name__ == '__main__':
     app.run(debug=True)

图书管理系统（数据库基本的操作）

 <!DOCTYPE html>
 <html lang="en">
 <head>
     <meta charset="UTF-8">
     <title>Title</title>
 </head>
 <body>
 <form method="post" action="http://127.0.0.1:5000/index">
     {{ form.csrf_token() }}<br/>
     {{ form.author.label }}{{ form.author }}<br/>
     {{ form.book.label }}{{ form.book }}<br/>
     {{ form.submit }}<br/>
     {% for message in get_flashed_messages() %}
         {{ message }}
     {% endfor %}
 </form>
 <br/>
 <h1>图书管理界面</h1>
 <ul>
     {% for  author in authors %}
         <li> {{ author.name }}<a href="/delete_author/{{ author.id }}">删除作者</a></li>
         <ul>
             {% for  book in author.book %}
                 <li> {{ book.name }}<a href="/delete_book/{{ book.id }}">删除书名</a></li>
             {% endfor %}
         </ul>
     {% endfor %}
 </ul>

 </body>
 </html>

前端展示代码