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denmark-dawa

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A simple interface API for the DAWA service

Installation

npm install denmark-dawa

Documentation

DAWARequest = require('denmark-dawa')

DAWA (Danmarks Adressers Web API) is a service provided by the danish government, which exposes multiply APIs for getting address related information. The API is very simple, make a GET request and get a big JSON object.

However the naïve implementation is performance wise not optimal. This module does the following:

  • Adds a Accept-Encoding: gzip, deflate header for data compression.
  • Adds &ndjson= to the url to get a stream friendly interface and remove pretty printing.
  • Detects errors and create custom error objects (http://dawa.aws.dk/generelt#fejlhaandtering).
  • Parses the JSON as a stream and adds back pressure.

DAWARequest is a class constructor with the signature DAWARequest(pathname, query, settings):

// Gets zipcodes including special ones (stormodtagere) 
const req = new DAWARequest('/postnumre', {
  stormodtagere: true
});
 
req.on('data', function (item) {
  console.log(`${item.nr}${item.navn}`); // 0800: Høje Taastrup 
});
 
req.once('error', function (err) {
  throw err;
});

The settings object can be used to specify the protocol (http or https), http is the default:

const req = new DAWARequest('/postnumre', {
  stormodtagere: true
}, {
  protcol: 'https'
});

Note that this module doesn't support the pagination API that DAWA provides. However it is kinda broken anyway since you can't beyond 400000 items. And not really nessarry since the JSON is parsed as a stream. So just add { per_side : 1000000 } to the query object, to get all the requests.

If you think this is an issue, I would be happy to consider a pull request.