表单验证

@app.route('/', methods=['get', 'post'])
def index():
    append_form = Append()

    if request.method == 'POST':
        if append_form.validate_on_submit():
            author_name = append_form.au_info.data
            book_name = append_form.bk_info.data
            # 判断数据是否存在
            author = Author.query.filter_by(name=author_name).first()
            if not author:
                try:
                    # 先添加作者
                    author = Author(name=author_name)
                    db.session.add(author)
                    db.session.commit()
                    # 再添加书籍
                    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("数据添加错误")
            else:
                book_names = [book.name for book in author.books]
                if book_name in book_names:
                    flash('该作者已存在相同的书名')
                else:
                    try:
                        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('数据添加错误')
        else:
            flash('数据输入有问题')

    authors = Author.query.all()
    books = Book.query.all()
    return render_template('test2.html', authors=authors, books=books, append_form=append_form)

• 重新编写html文件展示列表书籍

<h2>书籍列表</h2>
<ul>
{% for author in authors %}
    <li>
        {{ author.name }}
        <ul>
            {% for book in author.books %}
                <li>{{ book.name }}
            {% else %}
                    <li>无书籍</li>
            {% endfor %}
        </ul>

    </li>
{% endfor %}
</ul>

• 在form标签下添加 flash 消息的显示

{% for message in get_flashed_messages() %}
{{ message }}
{% endfor %}