https://github.com/afrith/election-map-backend

Backend service for interactive SA election result map
https://github.com/afrith/election-map-backend

Last synced: 28 days ago
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Backend service for interactive SA election result map

• Host: GitHub
• URL: https://github.com/afrith/election-map-backend
• Owner: afrith
• License: mit
• Created: 2019-05-31T09:42:43.000Z (over 5 years ago)
• Default Branch: master
• Last Pushed: 2024-06-12T13:17:27.000Z (8 months ago)
• Last Synced: 2024-11-14T15:45:51.799Z (3 months ago)
• Language: PLpgSQL
• Size: 479 KB
• Stars: 7
• Watchers: 5
• Forks: 1
• Open Issues: 3
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
This is the backend that serves map tiles and data for the election map which

is deployed at https://elections.adrianfrith.com/. The repository for the

frontend is at https://github.com/afrith/election-map-frontend.

## Service

The service provides Mapbox Vector Tiles (MVTs) for five levels of electoral geography: province, district council, municipality, ward, and voting district. The tiles include selected data points from the election results for ease of rendering. The tiles are provided at URLs of the form `/tiles/{level}_{election}/{z}/{x}/{y}/tile.mvt`, where:

* `{level}` is one of "prov", "dist", "muni", "ward" or "vd", corresponding to the five levels of electoral geography listed above.

* `{election}` is be one of "npe2004", "npe2009", "npe2014" or "npe2019".

The service also provides an endpoint to fetch full details of election results for any electoral geography as a JSON document. This endpoint is provided at URLs of the form `/{election}/{ballot}/{level}/{code}`, where:

* `{level}` and `{election}` are as described above.

* `{ballot}` is either "nat" or "prov", for the national and provincial ballot results respectively.

* `{code}` is the unique code identifying a geography, which can also be found in the `code` property of objects in the  MVTs.

## Tech stack

* Data store

  * PostgreSQL

  * PostGIS

* Service

  * Node.js

  * Express.js

  * [TileStrata](https://github.com/naturalatlas/tilestrata)

  * `tilestrata-postgismvt` slightly modified (see [repo](https://github.com/afrith/tilestrata-postgismvt))

## Running

To run the service you need the data, which can be downloaded [here](https://stuff.adrianfrith.com/election-results-20190530.pg_dump) as a 1GB PostgreSQL dump file. Then you need to set three environment variables.

* `DATABASE_URL` is the URL of the PostgreSQL database (e.g. `postgres://localhost/election-results`).

* `TILECACHE_DIR` is the location of a directory to use to cache MVTs - since the data is unchanging the tiles never expire; if you need to clear the cache, delete the contents of this directory.

* `PORT` is the port on which the service will listen (defaults to 3000).

Then you can run `yarn build && yarn start` to run the service.