Source code for pygeoapi.provider.geojson

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# Authors: Matthew Perry <[email protected]>
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# Copyright (c) 2018 Matthew Perry
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import json
import logging
import os
import uuid

from pygeoapi.provider.base import BaseProvider

LOGGER = logging.getLogger(__name__)


[docs]class GeoJSONProvider(BaseProvider): """Provider class backed by local GeoJSON files This is meant to be simple (no external services, no dependencies, no schema) at the expense of performance (no indexing, full serialization roundtrip on each request) Not thread safe, a single server process is assumed This implementation uses the feature 'id' heavily and will override any 'id' provided in the original data. The feature 'properties' will be preserved. TODO: * query method should take bbox * instead of methods returning FeatureCollections, we should be yielding Features and aggregating in the view * there are strict id semantics; all features in the input GeoJSON file must be present and be unique strings. Otherwise it will break. * How to raise errors in the provider implementation such that * appropriate HTTP responses will be raised """ def __init__(self, provider_def): """initializer""" BaseProvider.__init__(self, provider_def)
[docs] def _load(self): """Load and validate the source GeoJSON file at self.data Yes loading from disk, deserializing and validation happens on every request. This is not efficient. """ if os.path.exists(self.data): with open(self.data) as src: data = json.loads(src.read()) else: data = { 'type': 'FeatureCollection', 'features': []} # Must be a FeatureCollection assert data['type'] == 'FeatureCollection' # All features must have ids, TODO must be unique strings for i in data['features']: i['id'] = i['properties'][self.id_field] return data
[docs] def query(self, startindex=0, limit=10, resulttype='results', bbox=[], datetime=None, properties=[], sortby=[]): """ query the provider :param startindex: 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) :returns: FeatureCollection dict of 0..n GeoJSON features """ # TODO filter by bbox without resorting to third-party libs data = self._load() data['numberMatched'] = len(data['features']) if resulttype == 'hits': data['features'] = [] else: data['features'] = data['features'][startindex:startindex+limit] data['numberReturned'] = len(data['features']) return data
[docs] def get(self, identifier): """ query the provider by id :param identifier: feature id :returns: dict of single GeoJSON feature """ all_data = self._load() for feature in all_data['features']: if str(feature['properties'][self.id_field]) == identifier: return feature # default, no match LOGGER.error('feature {} not found'.format(identifier)) return None
[docs] def create(self, new_feature): """Create a new feature :param new_feature: new GeoJSON feature dictionary """ all_data = self._load() # Hijack the feature id and make sure it's unique new_feature['properties']['id'] = str(uuid.uuid4()) all_data['features'].append(new_feature) with open(self.data, 'w') as dst: dst.write(json.dumps(all_data))
[docs] def update(self, identifier, new_feature): """Updates an existing feature id with new_feature :param identifier: feature id :param new_feature: new GeoJSON feature dictionary """ all_data = self._load() for i, feature in enumerate(all_data['features']): if feature['properties']['id'] == identifier: # ensure new_feature retains id new_feature['properties']['id'] = identifier all_data['features'][i] = new_feature break with open(self.data, 'w') as dst: dst.write(json.dumps(all_data))
[docs] def delete(self, identifier): """Updates an existing feature id with new_feature :param identifier: feature id """ all_data = self._load() for i, feature in enumerate(all_data['features']): if feature['properties']['id'] == identifier: all_data['features'].pop(i) break with open(self.data, 'w') as dst: dst.write(json.dumps(all_data))
def __repr__(self): return '<GeoJSONProvider> {}'.format(self.data)