GeoPackageLoader
The GeoPackageLoader
depends on the sql.js
npm module which has caused issues with certain JavaScript bundlers. It is recommended that you do your own tests before using the GeoPackageLoader
in your project.
GeoPackage loader
Loader | Characteristic |
---|---|
File Extension | .gpkg |
File Type | Binary |
File Format | GeoPackage |
Data Format | Geometry |
Supported APIs | load , parse |
Decoder Type | Asynchronous |
Worker Thread Support | No |
Usage​
To load all tables in a geopackage file as GeoJSON:
import {GeoPackageLoader, GeoPackageLoaderOptions} from '@loaders.gl/geopackage';
import {load} from '@loaders.gl/core';
import {Tables, ObjectRowTable, Feature} from '@loaders.gl/schema';
const optionsAsTable: GeoPackageLoaderOptions = {
geopackage: {
shape: 'tables',
sqlJsCDN: 'https://cdnjs.cloudflare.com/ajax/libs/sql.js/1.5.0/'
}
};
const tablesData: Tables<GeoJSONTable> = await load(url, GeoPackageLoader, optionsAsTable);
To load a specific table named feature_table
in a geopackage file as GeoJSON:
const optionsAsGeoJson: GeoPackageLoaderOptions = {
geopackage: {
shape: 'geojson',
table: 'feature_table',
sqlJsCDN: 'https://cdnjs.cloudflare.com/ajax/libs/sql.js/1.5.0/',
}
};
const geoJsonData: GeoJSONTable = await load(url, GeoPackageLoader, optionsAsGeoJson);
Options​
Option | Type | Default | Description |
---|---|---|---|
options.shape | String | 'tables' | 'geojson-table' | Output format. |
options.table | String | N/A | name of table to load |
geopackage.sqlJsCDN | String | 'https://cdnjs.cloudflare.com/ajax/libs/sql.js/1.5.0/' | CDN from which to load the SQL.js bundle. This is loaded asynchronously when the GeoPackageLoader is called on a file. |
Output​
The GeoPackageLoader
currently loads all features from all vector tables.
-
If
options.gis.format
is'tables'
(the default):Returns
Tables<ObjectRowTable>
, an object whose.tables
member is an array of objects withname
andtable
keys. Eachname
member holds the name of the GeoPackage table name, and each.table
member holds aTable
instance. TheTable.data
member is an array of GeoJSON features, whileTable.schema
describes the schema types of the original Sqlite3 table. -
If
options.gis.format
is'geojson'
:Returns
Record<string, Feature[]>
, an object mapping from table name to an array of GeoJSON features. TheFeature
type is defined in@loaders.gl/schema
.
Remarks​
options.geopackage.sqlJsCDN
: As of March 2022, SQL.js versions 1.6.0, 1.6.1, and 1.6.2 were tested as not working.
Future Work​
- Select a single vector layer/table to load. This could would fit well in the two-stage loader process, where the first stage reads metadata from the file (i.e. the list of available layers) and the second stage loads one or more tables.
- Binary and GeoJSON output. Right now the output is GeoJSON-only, and is contained within an object mapping table names to geometry data. This is the same problem as we discussed previously for MVT, where with GeoPackage especially it's decently likely to only desire a portion of the layers contained in the file.