spatial-d4science/doc/previews.rst

Previews for Spatial Formats

The extension includes some plugins that implement the IResourcePreview interface, allowing to preview spatial resource files. They are based in popular Javascript mapping libraries and should be really easy to extend and adapt to your own needs.

GeoJSON Preview

The GeoJSON previewer is based on Leaflet. It will render GeoJSON files on a map and add a popup showing the features properties, for those resources that have a format of geojson or gjson.

To enable the GeoJSON previewer you need to add the geojson_preview plugin to your ini file. This plugin also requires the resource_proxy plugin (Make sure you load the resource_proxy plugin before any other from the spatial extension):

ckan.plugins = resource_proxy geojson_preview

WMS Preview

The WMS previewer is based o OpenLayers. When the plugin is enabled, if datasets contain a resource that has wms format, the resource page will load a simple map viewer that will attempt to load the remote service layers, based on the GetCapabilities response.

To enable the WMS previewer you need to add the wms_preview plugin to your ini file. This plugin also requires the resource_proxy plugin (Make sure you load the resource_proxy plugin before any other from the spatial extension:

ckan.plugins = resource_proxy wms_preview

Note

Please note that the WMS previewer included in ckanext-spatial is just a proof of concept and has important limitations, and is just intended as a bootstrap for developers willing to build a more sophisticated one.

Some projects that have built more advanced map viewers and integrated them with CKAN include:

• Data.gov.uk (http://data.gov.uk):

  • https://github.com/datagovuk/ckanext-dgu
  • https://github.com/datagovuk/ckanext-os

• Catalog.data.gov (http://catalog.data.gov):

  • https://github.com/okfn/ckanext-geodatagov
  • https://github.com/chilukey/viewer