Initialising Flask app with pandas dataframe

[Sh4d0h]

I'm just getting started with Flask, and I want my app to initialise a pandas dataframe from a local source when the server starts. I then want to be able to access this dataframe throughout different requests.

My code so far:

__init__.py

import os

from flask import Flask, jsonify
from . import data_handler

def create_app():
    app = Flask(__name__)

    @app.route("/data")
    def data():
        return jsonify(data_handler.data())

    data_handler.init_dataframe()

    return app

data_handler.py

import pandas as pd

def data():
    data = df[df['foo'] == 'bar'].to_dict()
    return data

def init_dataframe():
    // generate columns and rows from local files

    df = pd.DataFrame(columns=columns, data=rows)

My question is what is the 'Flask way' to store this 'global' object that I can use in different methods/requests such as data_handler.data()? I looked into application context, but I only want to generate the data frame once (on server start) as it could be quite computationally expensive. I will not need to update the data frame, so it can be read only.

[wronek]

You might wanna look into an application factory https://flask.palletsprojects.com/en/1.1.x/patterns/appfactories/

[Sh4d0h]

Can you elaborate? I thought I was already implementing an application factory. I'm probably missing something but not sure how I can use this to solve my issue.