geodata 0.8.0-a.8

A geospatial client to read GeoJSON and OGC API Features data sources.

GeoJSON and OGC API clients for Dart

Features

• Client-side data source abstractions
  • common geospatial Web APIs
  • geospatial feature services
• Data source implementations to read geospatial features
  • GeoJSON features from Web APIs or files
  • OGC API Features based services
• Also (partially) conforming to following standards
  • OGC API Common

Package

This package is at BETA stage, interfaces not fully final yet.

This is a Dart package named geodata under the geospatial code repository.

To use, add the dependency in your pubspec.yaml:

dependencies:
  geodata: ^0.8.0-a.8

The package contains also following mini-libraries, that can be used to import only a certain subset instead of the whole geodata library:

Library	Exports also	Description
common		Common data structures and helpers (for links, metadata, paged responses).
core		Metadata and data source abstractions of geospatial Web APIs (ie. features).
geojson_client	common, core	A client-side data source to read GeoJSON data from web and file resources.
ogcapi_features_client	common, core	A client-side data source to read features from OGC API Features services.

All the mini-libraries have dependencies to equatable and geocore packages. The geojson_client and ogcapi_features_client libraries depends also on the http package. The geojson_client package uses dart:io functions for file access too.

Usage

This sample shows to read GeoJSON features from a web resource using a HTTP fetcher, and from a local file using a file fetcher.

Please see other examples too.

import 'package:geodata/geojson_client.dart';

Future<void> main(List<String> args) async {
  // read GeoJSON for earthquakes from web using HTTP(S)
  print('GeoJSON features from HTTP');
  await _readFeatures(
    geoJsonHttpClient(
      location: Uri.parse(
        'https://earthquake.usgs.gov/earthquakes/feed/v1.0/summary/'
        '2.5_day.geojson',
      ),
    ),
  );
}

Future<void> _readFeatures(FeatureSource source) async {
  // read features with error handling
  try {
    // get items or features from a source, maximum 5 features returned
    final items = await source.items(
      const FeatureItemsQuery(limit: 5),
    );

    // do something with features, in this sample just print them out
    for (final f in items.collection.features) {
      print('Feature with id: ${f.id}');
      print('  geometry: ${f.geometry}');
      print('  properties:');
      for (final key in f.properties.keys) {
        print('    $key: ${f.properties[key]}');
      }
    }
  } on FeatureException catch (e) {
    print('Reading GeoJSON resource failed: ${e.failure.name}');
    if (e.cause != null) {
      print('Cause: ${e.cause}');
    }
    if (e.trace != null) {
      print(e.trace);
    }
  } catch (e, st) {
    print('Reading GeoJSON resource failed: $e');
    print(st);
  }
}

Authors

This project is authored by Navibyte.

More information and other links are available at the geospatial repository from GitHub.

License

This project is licensed under the "BSD-3-Clause"-style license.

Please see the LICENSE.