python-aio-geojson-generic-client

This library provides convenient async generic access to GeoJSON feeds.

Installation

pip install aio-geojson-generic-client

Usage

See below for examples of how this library can be used. After instantiating a particular class - feed or feed manager - and supply the required parameters, you can call update to retrieve the feed data. The return value will be a tuple of a status code and the actual data in the form of a list of feed entries specific to the selected feed.

Status Codes

OK: Update went fine and data was retrieved. The library may still return empty data, for example because no entries fulfilled the filter criteria.
OK_NO_DATA: Update went fine but no data was retrieved, for example because the server indicated that there was not update since the last request.
ERROR: Something went wrong during the update

Parameters

Parameter	Description
`home_coordinates`	Coordinates (tuple of latitude/longitude)
`url`	URL of the GeoJSON feed

Supported Filters

Filter		Description
Radius	`filter_radius`	Radius in kilometers around the home coordinates in which events from feed are included.

Example

import asyncio
from aiohttp import ClientSession
from aio_geojson_generic_client import GenericFeed
async def main() -> None:
    async with ClientSession() as websession:    
        # Home Coordinates: Latitude: -33.0, Longitude: 150.0
        # Filter radius: 50 km
        feed = GenericFeed(websession, 
                           (-33.0, 150.0),
                           "https://www.rfs.nsw.gov.au/feeds/majorIncidents.json",
                           filter_radius=50)
        status, entries = await feed.update()
        print(status)
        print(entries)
asyncio.get_event_loop().run_until_complete(main())

Feed entry properties

Each feed entry is populated with the following properties:

Name	Description	Feed attribute
geometries	All geometry details of this entry.	`geometry`
coordinates	Best coordinates (latitude, longitude) of this entry.	`geometry`
external_id	The unique public identifier for this incident.	`id`, `guid`, `title` or hash of coordinates
title	Title of this entry (if provided).	`title`
distance_to_home	Distance in km of this entry to the home coordinates.	n/a
publication_date	The publication date of the entry (if provided).	`pubDate`
properties	All properties defined for this entry.	`properties`

Feed Manager

The Feed Manager helps managing feed updates over time, by notifying the consumer of the feed about new feed entries, updates and removed entries compared to the last feed update.

If the current feed update is the first one, then all feed entries will be reported as new. The feed manager will keep track of all feed entries' external IDs that it has successfully processed.
If the current feed update is not the first one, then the feed manager will produce three sets:
- Feed entries that were not in the previous feed update but are in the current feed update will be reported as new.
- Feed entries that were in the previous feed update and are still in the current feed update will be reported as to be updated.
- Feed entries that were in the previous feed update but are not in the current feed update will be reported to be removed.
If the current update fails, then all feed entries processed in the previous feed update will be reported to be removed.

After a successful update from the feed, the feed manager provides two different dates:

last_update will be the timestamp of the last update from the feed irrespective of whether it was successful or not.
last_update_successful will be the timestamp of the last successful update from the feed. This date may be useful if the consumer of this library wants to treat intermittent errors from feed updates differently.
last_timestamp (optional, depends on the feed data) will be the latest timestamp extracted from the feed data. This requires that the underlying feed data actually contains a suitable date. This date may be useful if the consumer of this library wants to process feed entries differently if they haven't actually been updated.