Create a Feature Collection from Postgis Geometries using Postgis >= 3.0.0

sijakubo@gmail.com ( Simon Jakubowski) — Thu, 27 Apr 2023 00:00:00 +0000

Generating a Feature and Feature Collection form postgis is rather simple. If you convert a simple GEOMETRY with the st_asgeojson postgis will generate a GeoJSON “geometry”.

SELECT st_asgeojson(f.geometry)
FROM field f;

will result in a single geometry:

{
  "type" : "Polygon",
  "coordinates" : [...]
}

If you provide a RECORD (since Postgis 3.0.0), postgis will generate a Feature with all the fields as Properties:

SELECT st_asgeojson(f.*)
FROM field f;

will result in:

{
  "type" : "Feature",
  "geometry" : {
    "type" : "Polygon",
    "coordinates" : [
      ...
    ]
  },
  "properties" : {
    "id" : "052ff36a-4ea7-4307-9bc3-414f49a62163",
    "area_square_meters" : 29434,
    "altitude" : 40,
    "granule_code" : "31UGT",
    "creation_date" : "2021-10-21T23:32:25.974059",
    "name" : "Simple test field",
    ...
  }
}

Where the field table having the Columns: id, area_square_meters, …

Testcontainers | Postgres: Postgis with Spring and Spock

sijakubo@gmail.com ( Simon Jakubowski) — Tue, 18 Oct 2022 00:00:00 +0000

A great way to include all the required resources for integration tests, Testcontainers provides an easy way to start docker containers from within your testcode. This removes the necessity to create test docker-compose.yml files and write README.md code on how to even run a test.

Here is a short example using testcontainers with Spring and Spock on a Postgis / Postgres database.

@SpringBootTest
@AutoConfigureMockMvc
@AutoConfigureTestDatabase(replace = AutoConfigureTestDatabase.Replace.NONE)
@ContextConfiguration(initializers = [Initializer.class])
class FieldControllerTest extends IntegrationTest {

  @Shared
  public static JdbcDatabaseContainer postgreSQLContainer = new PostgisContainerProvider()
    .newInstance()
    .withDatabaseName("integration-tests-db")
    .withUsername("sa")
    .withPassword("sa");


  static class Initializer implements ApplicationContextInitializer<ConfigurableApplicationContext> {

    void initialize(ConfigurableApplicationContext configurableApplicationContext) {
      postgreSQLContainer.start()
      TestPropertyValues.of(
        "spring.datasource.url=" + postgreSQLContainer.getJdbcUrl(),
        "spring.datasource.username=" + postgreSQLContainer.getUsername(),
        "spring.datasource.password=" + postgreSQLContainer.getPassword()
      ).applyTo(configurableApplicationContext.getEnvironment());
    }
  }

  @Autowired
  MockMvc mockMvc

  @Autowired
  FieldRepository fieldRepository

  void setup() {
    fieldRepository.save(new Field(
      UUID.fromString('ad68f894-c16b-4953-b577-7cddb3e85ae5'), "initSampleField",
      new Polygon(
        PositionSequenceBuilders.variableSized(G2D.class)
          .add(5.8208837124389, 51.0596004663904)
          .add(5.83490292265498, 51.0571257015788)
          .add(5.87078646658134, 51.0451607414904)
          .add(5.79146302423308, 51.0612386272784)
          .add(5.8208837124389, 51.0596004663904)
          .toPositionSequence(),
        CoordinateReferenceSystems.WGS84
      )
    ))
  }

  ...
}

To integrate testcontainers into your project, you’ll need the following dependencies:

Postgis - Tag - Simon Jakubowski

Create a Feature Collection from Postgis Geometries using Postgis >= 3.0.0

Testcontainers | Postgres: Postgis with Spring and Spock