Multicorn soilgrids_fdw

__init__.py

from multicorn import ForeignDataWrapper
import json
import urllib2


class SoilGridsForeignDataWrapper(ForeignDataWrapper):
    def __init__(self, options, columns):
        super(SoilGridsForeignDataWrapper, self).__init__(options, columns)


    def execute(self, quals, columns):
        row = {}
        lat_ok = False
        long_ok = False

        if quals:
            for qual in quals:
                if qual.field_name.lower() == 'latitude' and qual.operator == '=':
                    latitude = qual.value
                    lat_ok = True
                if qual.field_name.lower() == 'longitude' and qual.operator == '=':
                    longitude = qual.value
                    long_ok = True

            if lat_ok and long_ok:
                req = urllib2.Request(
                    'http://rest.soilgrids.org/query?lon={0}&lat={1}&attributes=PHIHOX&confidence=L,M,U&depths=sd1'.format(longitude, latitude))
                req.add_header('Content-Type', 'application/json;charset=UTF-8')
                resp = urllib2.urlopen(req)
                results = resp.read()
                results = json.loads(results)

                properties = results['properties']

                row['longitude'] = longitude
                row['latitude'] = latitude
                row['ph_l'] = properties['PHIHOX']['L']['sd1'] / 10.0
                row['ph_m'] = properties['PHIHOX']['M']['sd1'] / 10.0
                row['ph_u'] = properties['PHIHOX']['U']['sd1'] / 10.0
                row['depth'] = -0.025
                row['publication_date'] = properties["publication_date"].encode("utf-8")

                yield row