datalad/datalad-neuroimaging

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#   See COPYING file distributed along with the datalad package for the
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"""NIDM metadata extractor"""

# TODO: ATM this is just a minimalistic place holder to document how it works
# it doesn't do anything meaningful

import logging
lgr = logging.getLogger('datalad.metadata.extractors.nidm')

from datalad_deprecated.metadata.definitions import vocabulary_id
from datalad_deprecated.metadata.extractors.base import BaseMetadataExtractor


class MetadataExtractor(BaseMetadataExtractor):
    # this extractor instance knows:
    #   self.ds -- an instance of the dataset it shall operate on
    #   self.paths -- a list of paths within the dataset from which
    #                 metadata should be extracted, pretty much up to
    #                 the extractor if those those paths are used. They are
    #                 provided to avoid duplicate directory tree traversal
    #                 when multiples extractors are executed
    def get_metadata(self, dataset, content):
        # function gets two flags indicating whether to extract dataset-global
        # and/or content metadata

        # function returns a tuple
        # item 1: dict with dataset-global metadata (e.g. a NIDM blob)
        #         should come with a JSON-LD context for that blob, context
        #         is preserved during aggregation
        # item 2: generator yielding metadata dicts for each (file) path in the
        #         dataset. When querying aggregated metadata for a file, the dataset's
        #         JSON-LD context is assigned to the metadata dict, hence file metadata
        #         should not be returned with individual/repeated contexts, but rather
        #         the dataset-global context should provide all definitions
        return {
            '@context': {
                'myvocabprefix': {
                    '@id': 'http://purl.org/ontology/mydefinition',
                    'description': 'I am a vocabulary',
                    'type': vocabulary_id,
                },
                'mydurationkey': {
                    "@id": 'time:Duration',
                },
            },
            'mydurationkey': 0.6,
        }, \
            []