Flask--(一对多demo)作者书籍模型

一对多模型的增加和删除

后端实现：

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

app = Flask(__name__)
app.secret_key = "asdfdf"

# 配置数据库
app.config['SQLALCHEMY_DATABASE_URI'] = "mysql://root:mysql@127.0.0.1:3306/booktest"
app.config['SQLALCHEMY_TRACK_MODIFICATIONS'] = False

db = SQLAlchemy(app)

class AddBookForm(FlaskForm):
    """自定义添加书籍的表单"""
    author = StringField('作者：', validators=[InputRequired('请输入作者')])
    book = StringField('书名：', validators=[InputRequired('请输入书名')])
    submit = SubmitField('添加')

class Author(db.Model):
    """作者模型：一的一方"""
    __tablename__ = "authors"
    id = db.Column(db.Integer, primary_key=True)
    name = db.Column(db.String(64), unique=True)

    # 定义属性，以便作者模型可以直接通过该属性访问其多的一方的数据(书的数据)
    # backref 给 Book 也添加了一个 author 的属性，可以通过 book.author 获取 book 所对应的作者信息
    books = db.relationship('Book', backref='author')

class Book(db.Model):
    """书的模型：多的一方"""
    __tablename__ = "books"
    id = db.Column(db.Integer, primary_key=True)
    name = db.Column(db.String(64), unique=True)
    # 记录一的一方的id作为外键
    author_id = db.Column(db.Integer, db.ForeignKey(Author.id))

@app.route('/delete_author/<author_id>')
def delete_author(author_id):
    """删除作者以及作者所有的书籍"""

    try:
        author = Author.query.get(author_id)
    except Exception as e:
        print(e)
        return "查询错误"

    if not author:
        return "作者不存在"

    # 删除作者及其所有书籍

    try:
        # 先删除书籍
        Book.query.filter(Book.author_id == author_id).delete()
        # 再删除指定作者
        db.session.delete(author)
        db.session.commit()
    except Exception as e:
        print(e)
        db.session.rollback()
        return "删除失败"

    return redirect(url_for('index'))

@app.route('/delete_book/<book_id>')
def delete_book(book_id):
    """删除书籍"""
    try:
        book = Book.query.get(book_id)
    except Exception as e:
        print(e)
        return "查询错误"

    if not book:
        return "书籍不存在"

    try:
        db.session.delete(book)
        db.session.commit()
    except Exception as e:
        print(e)
        db.session.rollback()
        return '删除失败'

    return redirect(url_for('index'))

@app.route('/', methods=['get', 'post'])
def index():
    """返回首页"""

    book_form = AddBookForm()

    # 如果book_form可以被提交
    if book_form.validate_on_submit():
        # 1. 取出表单中数据
        author_name = book_form.author.data
        book_name = book_form.book.data

        # 2. 做具体业务逻辑代码实现
        # 2.1 查询指定名字的作者
        author = Author.query.filter(Author.name == author_name).first()
        # if 指定名字的作者不存在：
        if not author:
            try:
                # 添加作者信息到数据库
                # 初始化作者的模型对象
                author = Author(name=author_name)
                db.session.add(author)
                db.session.commit()

                # 添加书籍信息到数据库(指定其作者)
                book = Book(name=book_name, author_id=author.id)
                db.session.add(book)
                db.session.commit()
            except Exception as e:
                db.session.rollback()
                print(e)
                flash("添加失败")
        else:
            book = Book.query.filter(Book.name == book_name).first()

            if not book:
                try:
                    # 添加书籍信息到数据库(指定其作者)
                    book = Book(name=book_name, author_id=author.id)
                    db.session.add(book)
                    db.session.commit()
                except Exception as e:
                    print(e)
                    flash("添加失败")
            else:
                flash("已存在")

    else:
        if request.method == "POST":
            flash('参数错误')

    # 1. 查询数据
    authors = Author.query.all()
    # 2. 将数据传入到模板中进行渲染返回
    return render_template('demo1_bookDemo.html', authors=authors, form=book_form)

if __name__ == '__main__':
    # 删除所有的表
    db.drop_all()
    # 创建所有的表
    db.create_all()

    au1 = Author(name='老王')
    au2 = Author(name='老尹')
    au3 = Author(name='老刘')
    # 把数据提交给用户会话
    db.session.add_all([au1, au2, au3])
    # 提交会话
    db.session.commit()
    bk1 = Book(name='老王回忆录', author_id=au1.id)
    bk2 = Book(name='我读书少，你别骗我', author_id=au1.id)
    bk3 = Book(name='如何才能让自己更骚', author_id=au2.id)
    bk4 = Book(name='怎样征服美丽少女', author_id=au3.id)
    bk5 = Book(name='如何征服英俊少男', author_id=au3.id)
    # 把数据提交给用户会话
    db.session.add_all([bk1, bk2, bk3, bk4, bk5])
    # 提交会话
    db.session.commit()

    app.run(debug=True)

前端实现：

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>

<h1>图书管理</h1>

<form method="post">
    {{ 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>

<hr>

<ul>
    {% for author in authors %}
        <li>{{ author.name }}<a href="/delete_author/{{ author.id }}">删除</a></li>
        <ul>
        {% for book in author.books %}
            <li>{{ book.name }}<a href="/delete_book/{{ book.id }}">删除</a></li></li>
        {% endfor %}
        </ul>
    {% endfor %}
</ul>

</body>
</html>