feature<T extends Geometry> method

@override Feature<T> feature<T extends Geometry>(dynamic data)

Parses a feature from a data object.

Throws FormatException if parsing fails.

Implementation

@override
Feature<T> feature<T extends Geometry>(dynamic data) {
  // expects data of Map<String, dynamic> as returned by json.decode()
  final json = _ensureDecodedMap(data);
  if (json['type'] != 'Feature') {
    throw const FormatException('Not valid GeoJSON Feature.');
  }

  // parse id as String?
  // (GeoJSON allows num and String types for ids - both represented here
  // as String)
  final dynamic id = json['id'];
  if (!(id == null || id is String || id is int || id is BigInt)) {
    throw const FormatException('Id should be null, int, BigInt or String');
  }

  // parse optional geometry for this feature
  final dynamic geomJson = json['geometry'];
  final geom = geomJson != null ? geometry<T>(geomJson) : null;

  // parse optional bbox
  // (bbox is not required on GeoJSON and not on Feature either)
  final bboxJson = json['bbox'] as Iterable?;
  final bbox = bboxJson != null ? bounds(bboxJson) : null;

  // create a feature using the factory function
  return featureFactory<T>(
    // nullable id
    id: id,

    // map of properties may be missing on GeoJSON, but for a feature
    // non-null map (even empty) is required
    properties: json['properties'] as Map<String, Object?>? ?? {},

    // nullable geometry object
    geometry: geom,

    // nullable bounds object
    bounds: bbox,

    // the JSON Object from source data provided as-is
    // (this lets custom feature factories to parse properties not known by
    //  the JSON specification)
    jsonObject: json,
  );
}