重新启动应用程序后删除添加的数据库记录（heroku/SQLAlchemy）

Question

So here's my problem: I created a heroku app that is working as expected, although when the app is restarted, all the new records in the database are deleted. The ones from my local database that were copied when I "pushed to heroku" are still there.

I am new to PostgresSQL, but I carefully follewed instructions to deploy my code to heroku and set up the database. Here's part of my configuration:

# defines the full path for the database
DATABASE_PATH = os.path.join(basedir, DATABASE)
# the database uri
SQLALCHEMY_DATABASE_URI = 'sqlite:///' + DATABASE_PATH

I know that last line is not how a connection with a heroku db should be established (sqlite), though I'd still like to know what is happening.

When I add data to my database I use db.session.add(data) and db.session.commit(). I created a heroku database like so:

$ heroku addons:create heroku-postgresql:hobby-dev

What happens when the app is restarted? I am probably missing something obvious.

EDIT

@admin_blueprint.route('/modify/add-post/',methods=['GET', 'POST'])
@login_required
def add_post():
    error = None
    form = AddPostForm(request.form)
    if request.method == 'POST':
        if form.validate_on_submit():
            now=datetime.datetime.now()  
            poster=session['adminname']
            new_post = Post(form.text.data,poster, now,form.add_file.data)
            db.session.add(new_post)
            db.session.commit()

            return redirect(url_for('home.posts'))
        else: 
            return render_template("adm_posts.html",error=error,form=form)

    if request.method == 'GET':
        return render_template("adm_posts.html",form=form)

Thanks!

Answer 1

Two things - 1) you connect to your PostgreSQL instance using the configuration that Heroku provides in the environment. Simply use:

import os
SQL_ALCHEMY_DATABASE_URI = os.environ['DATABASE_URL']

The environment variable DATABASE_URL will be populated by Heroku, and have the connection information (host, username, password, database).

2) The Heroku filesystem is ephemeral , and does not persist between dyno restarts. That is why your sqlite database disappears.