Forecast Notifications

Author: Marius Moldovan

The Forecast Notifications module is designed to notify subscribers when the forecasted values for a country change by a certain percentage.

It can be executed through the /send-bulk-emails endpoint with the topic_id set to the mongoDB document ID of the forecasts topic.

Environment Variables and Setup

• DATA_CHANGE_THRESHOLD: The percentage change threshold for the forecasted values to trigger an email notification. Default value is 15.

A cron job needs to be set up to run which calls the /send-bulk-emails endpoint.

Process

1. send_forecast_bulk_emails checks for every subscriber of the topic if any of his subscribed countries have a forecasted value change greater than the threshold. This check if being performed by sending a request to the /{adm0Id}/notification-check.json endpoint on the HungerMap API. Responses from the HungerMap API are cached, resulting in a maximum of 1 request per country.
2. If yes, an email with all the relevant forecasted values is generated and sent to the subscriber.

Classes and Functions

Function: send_forecast_bulk_emails(topic):

Checks if subscribers to topic should be notified and if so, sends an email to all subscribers.

Params:

• topic (dict): The topic document

Returns:

• None

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Function: check_send_email_condition(country_id):

Checks if the email should be sent to the subscriber based on the data change threshold and builds context object for the email generation.

Params:

• country_id (str): ID of the country to check for data change. This is the document ID of the country in the 'countries' collection.

Returns:

• tuple: A tuple containing a boolean value indicating if the email should be sent and the email_context object.

email_context = {
    "country_id": Int,
    "percentage_fcs": Int,
    "percentage_rcsi": Int,
    "country_name": String,
    "last_date": String,
    "last_fcs_value": Int,
    "last_rcsi_value": Int,
    "first_date_percentage_change_fcs": String,
    "first_date_percentage_chang_rcsi": String,
    "fcs_prediction": List containing the fcs prediction values (dict with fields: fcs, fcsHIgh, fcsLow, x),
    "rcsi_prediction": List containing the rcsi prediction values (dict with fields: rcsi, rcsiHIgh, rcsiLow, x),
}

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Function: calculate_percentage_change(old_value, new_value):

Calculates the percentage change between two values.

Params:

• old_value (int): The old value
• new_value (int): The new value

Returns:

• int: The percentage change between the two values