Schemas Support

Schema support is implemented in a separate library: OgcApi.Net.Schemas. It supports both SQL and MbTiles data providers.

Related documentation in the standard: OGC API - Features - Part 5: Schemas.

Enabling Schema Support

To enable schema support in your application:

  1. Install the OgcApi.Net.Schemas module.
  2. Register it using the AddSchemasOpenApiExtension() method before calling AddOgcApi(): 
    services.AddSchemasOpenApiExtension();
services.AddOgcApi("ogcapi.json");

Once registered, the following endpoints will be available:

Endpoint Description
GET /collections/{collectionId}/schema Returns the full JSON Schema describing features in the collection.
GET /collections/{collectionId}/queryables Returns the schema with all queryable properties (response equals /schema path).
GET /collections/{collectionId}/sortables Returns the schema with all sortable properties (currently always empty).

Schema Options

The SchemaOptions configuration includes:

  • Title: Title of the collection.
  • Description: Description of the collection.
  • AdditionalProperties: Boolean flag indicating whether additional properties are allowed in feature objects.
  • Properties: Dictionary mapping property names to their PropertyDescription.

Property Description

Each property description includes:

  • Type: Type of the property. The standard recommends using one of the following: string, number, integer, boolean, object or array.
  • Title: Human-readable title for the property.
  • Description: Description of the property.
  • XOgcRole: Custom OGC role (id, primary-geometry, type, etc.).
  • Format: Format of the property. For geometry properties, use one of: geometry-point, geometry-multipoint, geometry-linestring, geometry-multilinestring, geometry-polygon, geometry-multipolygon, geometry-geometrycollection, geometry-any.
  • XOgcPropertySeq: Sequence number of the property (not yet used).

Options example 

{
	"Id": "Test",
	"Title": "Test collection",
	"Features": {
		"Crs": [
			"http://www.opengis.net/def/crs/OGC/1.3/CRS84",
			"http://www.opengis.net/def/crs/EPSG/0/3857"
		],
		"StorageCrs": "http://www.opengis.net/def/crs/EPSG/0/3857",
		"Storage": {
			"Type": "PostGis",
			"ConnectionString": "Host=localhost;User Id=postgre;Password=myStrongP@ssword;Database=Tests;Port=5432;Timeout=50;",
			"Schema": "test",
			"Table": "test_table",
			"GeometryColumn": "geom",
			"GeometrySrid": 3857,
			"GeometryDataType": "geometry",
			"GeometryGeoJsonType": "MultiPolygon",
			"IdentifierColumn": "id",
			"DateTimeColumn": "date"
		}
	},
	"SchemaOptions": {
		"Title": "collection title",
		"Description": "collection description",
		"Properties": {
			"name": {
				"Title": "Name",
				"Description": "decription of property",
				"Type": "string"
			},
			"number": {
				"Title": "Number"
			},
			"id": {
				"Title": "Id"
			},
			"date": {
				"Title": "Date"
			}
		}
	}
}

Notes

  • If the SchemaOptions section is not specified, property names and types will be retrieved from the data provider.
  • If the Features.Storage.Properties list is defined, the generated schema will include only those properties, with IdentifierColumn used as the ID and GeometryColumn as the geometry.
  • If a property does not have an explicit Type defined, the type will be inferred from the data source.
  • The format and x-ogc-role must be explicitly set for geometry properties. If the format is not specified, it will be obtained: for mbtiles - it will be read from mbtiles metadata, for collections that have Features.Storage.GeometryGeoJsonType - from this field. If x-ogc-role is not provided, it will default to primary-geometry for geometry property.
  • If the IdentifierColumn is set in Features.Storage, the corresponding property with the same name will be assigned the x-ogc-role value: id.

For more details about the Features API, see Features API.