Flask Web App中未显示SQLite查询结果

我正在尝试学习烧瓶,所以决定遵循本教程:

https://www.blog.pythonlibrary.org/2017/12/14/flask-101-adding-editing-and-displaying-data/

我刚刚更新了以下主要功能:

@app.route('/results')
def search_results(search):
    results = []
    search_string = search.data['search']

    if search.data['search'] == '':
        qry = db_session.query(Album)
        results = qry.all()

    if not results:
        flash('No results found!')
        return redirect('/')
    else:
        # display results
        table = Results(results)
        table.border = True
        return render_template('results.html', table=table)

但是当我向数据库中添加一个相册并尝试使用search选项查询它时,它会说没有结果。数据库文件是正确创建的,到目前为止,我拥有与教程中完全相同的代码。

我做的唯一更改是从表中添加导入结果。下面是完整的main.py。你能告诉我在哪里找罪犯吗?如我所说,只是学习,所以任何建议重新资源友好的布局将非常感谢(初学者程序员)。

from app import app
from db_setup import init_db, db_session
from forms import MusicSearchForm, AlbumForm
from flask import flash, render_template, request, redirect
from models import Album, Artist
from tables import Results 

init_db()


def save_changes(album, form, new=False):
    """
    Save the changes to the database
    """
    # Get data from form and assign it to the correct attributes
    # of the SQLAlchemy table object
    artist = Artist()
    artist.name = form.artist.data

    album.artist = artist
    album.title = form.title.data
    album.release_date = form.release_date.data
    album.publisher = form.publisher.data
    album.media_type = form.media_type.data

    if new:
        # Add the new album to the database
        db_session.add(album)

    # commit the data to the database
    db_session.commit()


@app.route('/', methods=['GET', 'POST'])
def index():
    search = MusicSearchForm(request.form)
    if request.method == 'POST':
        return search_results(search)

    return render_template('index.html', form=search)


@app.route('/results')
def search_results(search):
    results = []
    search_string = search.data['search']

    if search.data['search'] == '':
        qry = db_session.query(Album)
        results = qry.all()

    if not results:
        flash('No results found!')
        return redirect('/')
    else:
        # display results
        table = Results(results)
        table.border = True
        return render_template('results.html', table=table)


@app.route('/new_album', methods=['GET', 'POST'])
def new_album():
    """
    Add a new album
    """
    form = AlbumForm(request.form)

    if request.method == 'POST' and form.validate():
        # save the album
        album = Album()
        save_changes(album, form, new=True)
        flash('Album created successfully!')
        return redirect('/')

    return render_template('new_album.html', form=form)


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