# Spatial Module

Nitrite Spatial module provides support for spatial queries. The module uses JTS port of the dart package dart_jts for spatial operations.

To use Spatial module to your project, you need to add below dependency to your project:

dart pub add nitrite
dart pub add nitrite_spatial

To use Spatial module, you need to load the SpatialModule while opening the database.

import 'package:nitrite/nitrite.dart';
import 'package:nitrite_spatial/nitrite_spatial.dart';

var db = await Nitrite.builder()
            .loadModule(SpatialModule())
            .openOrCreate();

If you are using nitrite_hive_adapter as your storage module, you need to register the GeometryAdapter with the Hive database.

import 'package:nitrite_hive_adapter/nitrite_hive_adapter.dart';

var storeModule = HiveModule.withConfig()
            .path(filePath)
            .addTypeAdapter(GeometryAdapter())
            .build();

var db = await Nitrite.builder()
            .loadModule(storeModule)
            .loadModule(SpatialModule())
            .openOrCreate();

If Nitrite is using the default SimpleNitriteMapper, then the SpatialModule will automatically register the GeometryConverter with the mapper. If you are using your own custom mapper, then you need to register the GeometryConverter with the mapper.

GeometryConverter is an EntityConverter which is used to convert Geometry object of Dart JTS to Document and vice-versa. It is used to store the Geometry object in the database.

Spatial module uses R-Tree index to store the spatial data.

To create a spatial index, you need to pass the index type as spatialIndex while creating the index. spatialIndex is a global constant defined in nitrite_spatial package.

await collection.createIndex(["location"], indexOptions(spatialIndex));

Spatial module supports several filters to query spatial data. To know more about filters, please refer to Spatial Filters.