## Query features by spatial predicate, bounding box, or H3 cell

`FeatureCollection Elements.QueryPost(ElementQueryPostParams?parameters, CancellationTokencancellationToken = default)`

**post** `/api/v1/features`

Query features by spatial predicate, bounding box, or H3 cell

### Parameters

- `ElementQueryPostParams parameters`

  - `string bbox`

    Legacy shorthand. Bounding box: south,west,north,east. Use spatial predicates (near, within, intersects) instead.

  - `string contains`

    Geometry that features must contain

  - `string crosses`

    Geometry that features must cross

  - `string cursor`

    Cursor for pagination

  - `string format`

    Response format. json (default) returns paginated GeoJSON. geojson/csv/ndjson stream via chunked transfer encoding.

  - `string h3`

    Legacy shorthand. H3 cell index. Use spatial predicates instead.

  - `string intersects`

    Geometry that features must intersect

  - `Long limit`

    Maximum results (default 100, max 10000)

  - `string near`

    Point geometry for proximity search (lat,lng). Requires radius.

  - `Double outputBuffer`

    Buffer geometry by meters

  - `Boolean outputCentroid`

    Replace geometry with centroid

  - `string outputFields`

    Comma-separated property fields to include

  - `Boolean outputGeometry`

    Include geometry (default true)

  - `string outputInclude`

    Extra computed fields: bbox, distance, center

  - `Long outputPrecision`

    Coordinate decimal precision (1-15, default 7)

  - `Double outputSimplify`

    Simplify geometry tolerance in meters

  - `string outputSort`

    Sort by: distance, name, osm_id

  - `Double radius`

    Search radius in meters (for near) or buffer distance (for other predicates)

  - `string touches`

    Geometry that features must touch

  - `string type`

    Element types (comma-separated: node,way,relation)

  - `string within`

    Geometry that features must be within

### Returns

- `class FeatureCollection:`

  GeoJSON FeatureCollection (RFC 7946). For paginated endpoints, metadata is returned in HTTP response headers rather than the body:

| Header          | Description                                      |
| --------------- | ------------------------------------------------ |
| `X-Limit`       | Requested result limit                           |
| `X-Has-More`    | `true` if more results exist                     |
| `X-Next-Cursor` | Opaque cursor for next page (cursor pagination)  |
| `X-Next-Offset` | Numeric offset for next page (offset pagination) |
| `Link`          | RFC 8288 `rel="next"` link to the next page      |

  Content-Type is `application/geo+json`.

  - `required IReadOnlyList<GeoJsonFeature> Features`

    Array of GeoJSON Feature objects

    - `required GeoJsonGeometry Geometry`

      GeoJSON Geometry object per RFC 7946. Coordinates use [longitude, latitude] order. 3D coordinates [lng, lat, elevation] are used for elevation endpoints.

      - `required Coordinates Coordinates`

        Coordinates array. Nesting depth varies by geometry type: Point = [lng, lat], LineString = [[lng, lat], ...], Polygon = [[[lng, lat], ...], ...], etc.

        - `IReadOnlyList<Double>`

        - `IReadOnlyList<IReadOnlyList<Double>>`

        - `IReadOnlyList<IReadOnlyList<IReadOnlyList<Double>>>`

        - `IReadOnlyList<IReadOnlyList<IReadOnlyList<IReadOnlyList<Double>>>>`

      - `required Type Type`

        Geometry type

        - `"Point"Point`

        - `"LineString"LineString`

        - `"Polygon"Polygon`

        - `"MultiPoint"MultiPoint`

        - `"MultiLineString"MultiLineString`

        - `"MultiPolygon"MultiPolygon`

    - `required IReadOnlyDictionary<string, JsonElement> Properties`

      OSM tags flattened as key-value pairs, plus `@type` (node/way/relation) and `@id` (OSM ID) metadata fields. May include `distance_m` for proximity queries.

    - `required Type Type`

      Always `Feature`

      - `"Feature"Feature`

    - `string ID`

      Compound identifier in `type/osm_id` format

  - `required Type Type`

    Always `FeatureCollection`

    - `"FeatureCollection"FeatureCollection`

### Example

```csharp
ElementQueryPostParams parameters = new();

var featureCollection = await client.Elements.QueryPost(parameters);

Console.WriteLine(featureCollection);
```

#### Response

```json
{
  "features": [
    {
      "geometry": {
        "coordinates": [
          2.3522,
          48.8566
        ],
        "type": "Point"
      },
      "properties": {
        "@id": "bar",
        "@type": "bar",
        "amenity": "bar",
        "cuisine": "bar",
        "name": "bar"
      },
      "type": "Feature",
      "id": "node/21154906"
    }
  ],
  "type": "FeatureCollection"
}
```