pygeoapi/pygeoapi/provider/csv_.py

# =================================================================
#
# Authors: Tom Kralidis <tomkralidis@gmail.com>
#
# Copyright (c) 2021 Tom Kralidis
#
# Permission is hereby granted, free of charge, to any person
# obtaining a copy of this software and associated documentation
# files (the "Software"), to deal in the Software without
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# copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the
# Software is furnished to do so, subject to the following
# conditions:
#
# The above copyright notice and this permission notice shall be
# included in all copies or substantial portions of the Software.
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# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
# OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
# HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
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# FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
# OTHER DEALINGS IN THE SOFTWARE.
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# =================================================================

from collections import OrderedDict
import csv
import itertools
import logging

from pygeoapi.provider.base import (BaseProvider, ProviderQueryError,
                                    ProviderItemNotFoundError)

LOGGER = logging.getLogger(__name__)


class CSVProvider(BaseProvider):
    """CSV provider"""

    def __init__(self, provider_def):
        """
        Initialize object

        :param provider_def: provider definition

        :returns: pygeoapi.provider.csv_.CSVProvider
        """

        super().__init__(provider_def)
        self.geometry_x = provider_def['geometry']['x_field']
        self.geometry_y = provider_def['geometry']['y_field']
        self.fields = self.get_fields()

    def get_fields(self):
        """
         Get provider field information (names, types)

        :returns: dict of fields
        """

        LOGGER.debug('Treating all columns as string types')
        with open(self.data) as ff:
            LOGGER.debug('Serializing DictReader')
            data_ = csv.DictReader(ff)
            fields = {}
            for f in data_.fieldnames:
                fields[f] = {'type': 'string'}
            return fields

    def _load(self, offset=0, limit=10, resulttype='results',
              identifier=None, bbox=[], datetime_=None, properties=[],
              select_properties=[], skip_geometry=False, q=None):
        """
        Load CSV data

        :param offset: starting record to return (default 0)
        :param limit: number of records to return (default 10)
        :param datetime_: temporal (datestamp or extent)
        :param resulttype: return results or hit limit (default results)
        :param properties: list of tuples (name, value)
        :param select_properties: list of property names
        :param skip_geometry: bool of whether to skip geometry (default False)
        :param q: full-text search term(s)

        :returns: dict of GeoJSON FeatureCollection
        """

        found = False
        result = None
        feature_collection = {
            'type': 'FeatureCollection',
            'features': []
        }

        with open(self.data) as ff:
            LOGGER.debug('Serializing DictReader')
            data_ = csv.DictReader(ff)
            if properties:
                data_ = filter(
                    lambda p: all(
                        [p[prop[0]] == prop[1] for prop in properties]), data_)

            if resulttype == 'hits':
                LOGGER.debug('Returning hits only')
                feature_collection['numberMatched'] = len(list(data_))
                return feature_collection
            LOGGER.debug('Slicing CSV rows')
            for row in itertools.islice(data_, offset, offset+limit):
                feature = {'type': 'Feature'}
                feature['id'] = row.pop(self.id_field)
                if not skip_geometry:
                    feature['geometry'] = {
                        'type': 'Point',
                        'coordinates': [
                            float(row.pop(self.geometry_x)),
                            float(row.pop(self.geometry_y))
                        ]
                    }
                else:
                    feature['geometry'] = None
                if self.properties or select_properties:
                    feature['properties'] = OrderedDict()
                    for p in set(self.properties) | set(select_properties):
                        try:
                            feature['properties'][p] = row[p]
                        except KeyError as err:
                            LOGGER.error(err)
                            raise ProviderQueryError()
                else:
                    feature['properties'] = row

                if identifier is not None and feature['id'] == identifier:
                    found = True
                    result = feature
                feature_collection['features'].append(feature)
                feature_collection['numberMatched'] = \
                    len(feature_collection['features'])

        if identifier is not None and not found:
            return None
        elif identifier is not None and found:
            return result

        feature_collection['numberReturned'] = len(
            feature_collection['features'])

        return feature_collection

    def query(self, offset=0, limit=10, resulttype='results',
              bbox=[], datetime_=None, properties=[], sortby=[],
              select_properties=[], skip_geometry=False, q=None, **kwargs):
        """
        CSV query

        :param offset: starting record to return (default 0)
        :param limit: number of records to return (default 10)
        :param resulttype: return results or hit limit (default results)
        :param bbox: bounding box [minx,miny,maxx,maxy]
        :param datetime_: temporal (datestamp or extent)
        :param properties: list of tuples (name, value)
        :param sortby: list of dicts (property, order)
        :param select_properties: list of property names
        :param skip_geometry: bool of whether to skip geometry (default False)
        :param q: full-text search term(s)

        :returns: dict of GeoJSON FeatureCollection
        """

        return self._load(offset, limit, resulttype,
                          properties=properties,
                          select_properties=select_properties,
                          skip_geometry=skip_geometry)

    def get(self, identifier, **kwargs):
        """
        query CSV id

        :param identifier: feature id

        :returns: dict of single GeoJSON feature
        """
        item = self._load(identifier=identifier)
        if item:
            return item
        else:
            err = 'item {} not found'.format(identifier)
            LOGGER.error(err)
            raise ProviderItemNotFoundError(err)

    def __repr__(self):
        return '<CSVProvider> {}'.format(self.data)