OpenWeatherMap FDW

__init__.py

import requests
from multicorn import ForeignDataWrapper
from multicorn.utils import log_to_postgres, ERROR

__author__ = "Ernst-Georg Schmid"
__copyright__ = "Copyright (c) 2019 Ernst-Georg Schmid"
__license__ = "PostgreSQL"
__version__ = "2.0"

class OWMForeignDataWrapper(ForeignDataWrapper):
    """A multicorn based foreign data wrapper for Open Weather Map"""

    def __init__(self, options, columns):
        super(OWMForeignDataWrapper, self).__init__(options, columns)
        self.weather_api_url = options.get('weather_api_url', 'api.openweathermap.org/data/2.5/weather')
        self.uvi_api_url = options.get('uvi_api_url', 'api.openweathermap.org/data/2.5/uvi')
        self.https_proxy = options.get('https_proxy', None)
        self.api_key = options.get('api_key', None)
        self.default_language = options.get('default_language', 'en')

    def get_rel_size(self, quals, columns):
        """Inform the planner about the cost of a query"""
        width = len(columns) * 100
        nb_rows = 1

        return (nb_rows, width)

    def execute(self, quals, columns, sortkeys=None):
        """Execute a query"""
        url = 'https://{}'.format(self.weather_api_url)
        row = {}
        proxies = None
        lat_ok = False
        long_ok = False
        language = self.default_language

        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 qual.field_name.lower() == 'language' and qual.operator == '=':
                    language = qual.value
                    language = language.lower()

            if self.api_key and lat_ok and long_ok:
                query_params = {'appid': self.api_key, 'lat': latitude, 'lon': longitude, 'lang': language}
                if self.https_proxy:
                    proxies = {'https': self.https_proxy}

                with requests.Session() as s:
                    r = s.get(url, params=query_params, proxies=proxies)

                    if requests.codes.ok == r.status_code:
                        row['latitude'] = latitude
                        row['longitude'] = longitude
                        row['language'] = language
                        row['weather_data'] = r.text

                        url = 'https://{}'.format(self.uvi_api_url)
                        r = s.get(url, params=query_params, proxies=proxies)

                        if requests.codes.ok == r.status_code:
                            row['uvi_data'] = r.text
                            yield row
                        else:
                            log_to_postgres('Call to {} returned HTTP {}.'.format(url, r.status_code), ERROR)
                    else:
                        log_to_postgres('Call to {} returned HTTP {}.'.format(url, r.status_code), ERROR)