JSON-LD - Linked-data

[mahsa-frj]

Hi everyone,

I’m using the Docker version of pygeoapi and decided to try the linked-data feature. I noticed that linked-data works properly with the non-Docker version of pygeoapi, but not with the Docker image.

Could someone please help me understand what might be causing this issue?

Thanks in advance!

[tomkralidis]

@mahsa-frj can you provide a test case that we can reproduce?

[mahsa-frj]

Hi @tomkralidis, Thanks for your reply.

Yes, I am using the following command with the predefined resources (such as observations, lake, etc.) without any changes. In the observations collection, we have the linked-data block configured.

sudo docker run -d -p 5000:80 -it geopython/pygeoapi

resources:
    obs:
        type: collection
        title: Observations
        description: My cool observations
        keywords:
            - observations
            - monitoring
        linked-data:
            context:
                - datetime: https://schema.org/DateTime
                - vocab: https://example.com/vocab#
                  stn_id: "vocab:stn_id"
                  value: "vocab:value"

However, when I open the collections in the browser, I cannot see the context in either the items JSON-LD or the collections JSON-LD, as shown in the attached image.

When I tested with my previous pygeoapi installation (without Docker, version pygeoapi 0.20.dev0), the observations linked-data information was displayed correctly. But with the newer version of pygeoapi (again without Docker), the linked-data context is no longer shown.

To investigate further, I modified the linked-data.py code to explicitly pass the context. With this change, the context now appears in the items JSON-LD but still does not show up in the collections JSON-LD. I am currently working on this.

def geojson2jsonld(cls, data: dict, dataset: str,
                   identifier: str = None, id_field: str = 'id') -> str:
    """
    Render GeoJSON-LD from a GeoJSON base. Inserts a @context exactly
    from the pygeoapi configuration for a particular dataset if present.
    No merging with defaults unless context is missing.

    :param cls: API object
    :param data: dict of data
    :param dataset: dataset identifier
    :param identifier: item identifier (optional)
    :param id_field: item identifier_field (optional)

    :returns: string of rendered JSON (GeoJSON-LD)
    """

    LOGGER.debug('Fetching context from resource configuration')
    context = cls.config['resources'][dataset].get('linked-data', {}).get('context', []).copy()
    print("RESOURCES KEYS:", cls.config['resources'].keys())
    print(f"{dataset} linked-data section:", cls.config['resources'][dataset].get('linked-data'))
    templates = cls.get_dataset_templates(dataset)

    # Only used if no context provided in config
    defaultVocabulary_item = {
        'schema': 'https://schema.org/',
        'gsp': 'http://www.opengis.net/ont/geosparql#',
        'type': '@type'
    }
    defaultVocabulary_collection = {
        **defaultVocabulary_item,
        'features': 'schema:itemListElement',
        'FeatureCollection': 'schema:itemList'
    }

    if identifier:
        # Single item
        data.update(data.pop('properties'))

        if data.get('geometry') is not None:
            jsonldify_geometry(data)

        data['@id'] = identifier

        ldjsonData = {
            '@context': context or [defaultVocabulary_item],
            **data
        }

        LOGGER.debug('Rendering JSON-LD item template')
        content = render_j2_template(
            cls.tpl_config, templates,
            'collections/items/item.jsonld', ldjsonData
        )

    else:
        # Collection
        ds_url = url_join(cls.get_collections_url(), dataset)
        data['@id'] = ds_url

        for i, feature in enumerate(data['features']):
            identifier_ = feature.get(id_field,
                                      feature['properties'].get(id_field, ''))
            if not is_url(str(identifier_)):
                identifier_ = f"{ds_url}/items/{feature['id']}"

            if feature.get('geometry') is not None:
                jsonldify_geometry(feature)

            data['features'][i] = {
                '@id': identifier_,
                'type': 'schema:Place',
                **feature.pop('properties'),
                **feature
            }

        if data.get('timeStamp', False):
            data['https://schema.org/sdDatePublished'] = data.pop('timeStamp')

        data['links'] = data.pop('links')

        ldjsonData = {
            '@context': context or [defaultVocabulary_collection],
            **data
        }

        LOGGER.debug('Rendering JSON-LD items template')
        content = render_j2_template(
            cls.tpl_config, templates,
            'collections/items/index.jsonld', ldjsonData
        )

    return content

If you have any ideas or suggestions to help resolve this issue, I would greatly appreciate it. Once I solve the problem, I will also share my updated code so that the context is included in each collection.

Thanks in advance.

[mahsa-frj]

Update:
I have changed the example-config.yanl to new format like below (removed the linked-data)

        keywords:
            - observations
            - monitoring
        context:
           - datetime: https://schema.org/DateTime
           - vocab: https://example.com/vocab#
             stn_id: "vocab:stn_id"
             value: "vocab:value"

and also I changed the index.jsonld to:

{
    "@context": {{ to_json(data["@context"], config.server.pretty_print) | safe }},
    "type": "FeatureCollection",
    "@id": "{{ data["@id"] }}",
    {%- if data.features %}
    "features": [
        {%- for ft in data.features %}
        {
            "@type": "{{ ft.type }}",
            "@id": "{{ ft["@id"] }}"
        }
        {%- if not loop.last -%},{%- endif -%}
        {%- endfor %}
    ]
    {%- endif %}
}

and now the context is available in both "/collections/obs/items?f=jsonld" and "/collections/obs/items/371?f=jsonld".

But if you have any further suggestions, please share them with me.
Thanks