Inserting a value with SQLite3 and Python/Flask

Question

I am working in a small website where I want to show, insert, edit and delete elements from the database

I accomplished showing the data with this route:

@app.route('/objects')
def objects():
    g.db = sqlite3.connect(db_location)
    cur = g.db.execute('SELECT * FROM milkyway ORDER BY type')
    objects = [dict(id=row[0], type=row[1], name=row[2], description=row[3],  size=row[4], mass=row[5],distance=row[6], discoverer=row[7], image_url=row[8])   for row in cur.fetchall()]
    g.db.close()
    return render_template("objects.html",objects=objects)

And now I am trying to insert an element but I receive an error "AttributeError: '_AppCtxGlobals' object has no attribute 'db'"

@app.route('/insert_value',methods = ['POST', 'GET'])
def insert_value():
    atype = request.form['type']
    name = request.form['name']
    description = request.form['description']
    size = request.form['size']
    mass = request.form['mass']
    distance = request.form['distance']
    discoverer = request.form['discoverer']
    image_url = request.form['image_url']

    g.db.execute('INSERT INTO milkyway  (type,name,description,size,mass,distance,discoverer,image_ur) VALUES (?,?,?,?,?,?,?,?)', [atype], [name], [description], [size], [mass], [distance], [discoverer], [image_url] )

    g.db.commit()
    return redirect(url_for('objects'))

I search everywhere but the thing is, there are so many different ways to do this and I cannot make it works. I followed for instance this example; http://opentechschool.github.io/python-flask/extras/databases.html

xli · Accepted Answer · 2016-10-22 18:53:07Z

2

The connection, g.db, needs to be added with each request. You only create it in objects, so it doesn't exist for insert_value. g is an object which is created in the context of each request.

As the example code shows, you should create the connection before each request and add it to g.

@app.before_request
def before_request():
    g.db = sqlite3.connect(db_location)

Be sure to also close it in @app.teardown_request.

answered Oct 22, 2016 at 18:53

xli

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5 Comments

Adrian Vazquez Over a year ago

I have another error, TypeError: function takes at most 2 arguments (9 given). I think its because I did not add the first one the ID. The id is autoincrement, how can leave it blank in order to do it automaticly?

xli Over a year ago

In g.db.execute, [atype, name, description,...] not [atype], [name].... Pass in a list of statement parameters, not each parameter as an argument in its own list.

Adrian Vazquez Over a year ago

You are awesome! last question, any good resources for these? books, tutorials or examples?

xli Over a year ago

This is a good Flask tutorial. See this explanation of flask g. This explains how to use the DB API.

Adrian Vazquez Over a year ago

Thank very much :)

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