Allow swapping EE backends based on USE_LOCAL_PARQUET_ELECTIONS

polling_stations/apps/api/postcode.py

@@ -1,13 +1,11 @@
 from data_finder.helpers import (
-    EveryElectionWrapper,
     PostcodeError,
     RoutingHelper,
     geocode,
     get_council,
 )
 from data_finder.helpers.every_election import (
     EmptyEveryElectionWrapper,
-    StaticElectionsAPIElectionWrapper,
 )
 from data_finder.views import LogLookUpMixin, polling_station_current
 from django.core.exceptions import ObjectDoesNotExist
@@ -61,12 +59,12 @@ def get_ee_wrapper(self, postcode, rh, query_params):
         if rh.route_type == "multiple_addresses":
             return EmptyEveryElectionWrapper()
         if rh.elections_response:
-            return StaticElectionsAPIElectionWrapper(rh.elections_response)
+            return rh.elections_backend.ee_wrapper(rh.elections_response)
         kwargs = {}
         query_params = parse_qs_to_python(query_params)
         if include_current := query_params.get("include_current", False):
             kwargs["include_current"] = any(include_current)
-        return EveryElectionWrapper(postcode, **kwargs)
+        return rh.elections_backend.ee_wrapper(postcode, **kwargs)
 
     @extend_schema(
         parameters=[

polling_stations/apps/data_finder/helpers/baked_data_helper.py

@@ -1,10 +1,12 @@
 import abc
 import enum
 from pathlib import Path
-from typing import List, Optional, Tuple, Type
+from typing import List, Tuple
 from urllib.parse import urljoin
 
 import polars
+from data_finder.helpers import EveryElectionWrapper
+from data_finder.helpers.every_election import StaticElectionsAPIElectionWrapper
 from django.conf import settings
 from requests import Session
 from uk_geo_utils.helpers import Postcode
@@ -25,7 +27,7 @@ def ballot_paper_id_to_static_url(ballot_paper_id):
     return urljoin(settings.WCIVF_BALLOT_CACHE_URL, path)
 
 
-class BaseBakedElectionsStrategy(abc.ABC):
+class BaseBakedElectionsHelper(abc.ABC):
     def __init__(self, **kwargs):
         ...
 
@@ -34,25 +36,23 @@ def get_response_for_postcode(self, postcode: Postcode):
         raise NotImplementedError
 
 
-class RemoteBakedElectionsStrategy(BaseBakedElectionsStrategy):
-    def __init__(self, api_key=None, **kwargs):
-        self.api_key = api_key or getattr(settings, "DEVS_DC_API_KEY", None)
-        if not self.api_key:
-            raise ValueError("API key required for remote backend")
-        super().__init__(**kwargs)
+class NoOpElectionsHelper(BaseBakedElectionsHelper):
+    """
+    Just returns nothing, causing the app to use EE as it previously did.
+
+    This maintains the previous default behaviour for looking up elections
+
+    """
+
+    ee_wrapper = EveryElectionWrapper
 
     def get_response_for_postcode(self, postcode: Postcode):
-        # TODO: pull into a constant
-        devs_dc_base = "https://developers.democracyclub.org.uk"
-        req = session.get(
-            urljoin(devs_dc_base, f"/api/v1/elections/postcode/{postcode.with_space}/"),
-            params={"auth_token": self.api_key},
-        )
-        req.raise_for_status()
-        return req.json()
+        return {}
 
 
-class LocalParquetElectionsStrategy(BaseBakedElectionsStrategy):
+class LocalParquetElectionsHelper(BaseBakedElectionsHelper):
+    ee_wrapper = StaticElectionsAPIElectionWrapper
+
     def __init__(self, elections_parquet_path: Path = None, **kwargs):
         self.elections_parquet_path = elections_parquet_path or getattr(
             settings, "ELECTION_PARQUET_DATA_PATH", None
@@ -144,27 +144,20 @@ def get_ballot_list(self, postcode: Postcode) -> Tuple[bool, List]:
         return is_split, df["current_elections"][0].split(",")
 
 
-class BakedElectionsHelper:
-    """
-    Helper to get election data from "baked" data: a cut of EveryElection that's been
-    joined with AddressBase and stored in parquet files.
-
-    We host these files and proxy them via an API.
-
-    This helper allows us to consume the data either via parquet files or the API
-
-    """
-
-    def __init__(
-        self,
-        strategy: Optional[
-            Type[BaseBakedElectionsStrategy]
-        ] = LocalParquetElectionsStrategy,
-        **kwargs,
-    ):
-        self.strategy = strategy(**kwargs)
-
+class RemoteBakedElectionsHelper(BaseBakedElectionsHelper):
+    def __init__(self, api_key=None, **kwargs):
+        self.api_key = api_key or getattr(settings, "DEVS_DC_API_KEY", None)
+        if not self.api_key:
+            raise ValueError("API key required for remote backend")
+        super().__init__(**kwargs)
 
-if __name__ == "__main__":
-    helper = BakedElectionsHelper(strategy=None, api_key="asd")
-    helper.strategy.get_response_for_postcode(Postcode("GL5 1NA"))
+    def get_response_for_postcode(self, postcode: Postcode):
+        req = session.get(
+            urljoin(
+                settings.DEVS_DC_BASE,
+                f"/api/v1/elections/postcode/{postcode.with_space}/",
+            ),
+            params={"auth_token": self.api_key},
+        )
+        req.raise_for_status()
+        return req.json()

polling_stations/apps/data_finder/helpers/every_election.py

@@ -1,4 +1,5 @@
 import datetime
+from functools import cached_property
 from typing import List, Optional
 from urllib.parse import urlencode, urljoin
 
@@ -312,6 +313,19 @@ def get_ballots_for_next_date() -> List:
     def get_all_ballots() -> List:
         return []
 
+    @staticmethod
+    def multiple_elections():
+        return False
+
+    def get_explanations(self):
+        return None
+
+    def get_voter_id_status(self):
+        return None
+
+    def get_cancelled_election_info(self):
+        return {}
+
 
 class StaticElectionsAPIElectionWrapper:
     def __init__(self, elections_response):
@@ -323,7 +337,6 @@ def __init__(self, elections_response):
                 # so rename it back to what EE calls it
                 ballot["election_title"] = ballot["election_name"]
                 self.ballots.append(ballot)
-        ...
 
     def has_election(self, future_only=True):
         if not self.elections_response["dates"]:
@@ -367,12 +380,18 @@ def get_cancelled_election_info(self):
         if not rec["cancelled"]:
             return rec
 
-        cancelled_ballot = self.cancelled_ballots[0]
-        if len(self.cancelled_ballots) == 1:
-            rec["name"] = cancelled_ballot["election_title"]
-        rec["metadata"] = cancelled_ballot["metadata"]
+        cancelled_ballots = self.cancelled_ballots
+        if cancelled_ballots:
+            cancelled_ballot = cancelled_ballots[0]
+            if len(cancelled_ballots) == 1:
+                rec["name"] = cancelled_ballot["election_title"]
+            rec["metadata"] = cancelled_ballot["metadata"]
         return rec
 
+    @cached_property
+    def cancelled_ballots(self):
+        return [b for b in self.ballots if b["cancelled"]]
+
     def get_voter_id_status(self) -> Optional[str]:
         """
         For a given election, determine whether any ballots require photo ID

polling_stations/apps/data_finder/helpers/routing.py

@@ -4,7 +4,11 @@
 
 # use a postcode to decide which endpoint the user should be directed to
 from councils.models import CouncilGeography
-from data_finder.helpers.baked_data_helper import BakedElectionsHelper
+from data_finder.helpers.baked_data_helper import (
+    LocalParquetElectionsHelper,
+    NoOpElectionsHelper,
+)
+from django.conf import settings
 from django.urls import reverse
 from django.utils.functional import cached_property
 from uk_geo_utils.helpers import Postcode
@@ -21,7 +25,13 @@ class RoutingHelper:
     def __init__(self, postcode):
         self.postcode = Postcode(postcode)
         self.addresses = self.get_addresses()
-        self.elections_response = None
+        self.elections_backend = self.get_elections_backend()
+        self._elections_response = None
+
+    def get_elections_backend(self):
+        if getattr(settings, "USE_LOCAL_PARQUET_ELECTIONS", False):
+            return LocalParquetElectionsHelper
+        return NoOpElectionsHelper
 
     def get_addresses(self):
         return Address.objects.filter(postcode=self.postcode.with_space).select_related(
@@ -82,12 +92,17 @@ def addresses_have_single_station(self):
             return bool(list(self.polling_stations)[0])
         return False
 
+    @property
+    def elections_response(self):
+        if not self._elections_response:
+            self.lookup_elections()
+        return self._elections_response
+
     def lookup_elections(self):
-        helper = BakedElectionsHelper()
-        self.elections_response = helper.strategy.get_response_for_postcode(
+        self._elections_response = self.elections_backend().get_response_for_postcode(
             self.postcode
         )
-        return self.elections_response
+        return self._elections_response
 
     @property
     def split_elections(self):

polling_stations/apps/data_finder/views.py

@@ -300,14 +300,14 @@ def get_ee_wrapper(self, rh=None):
 
 
 class ExamplePostcodeView(BasePollingStationView):
-
     """
     This class presents a hard-coded example of what our website does
     without having to worry about having any data imported
     or whether an election is actually happening or not
     """
 
     def get(self, request, *args, **kwargs):
+        kwargs["rh"] = RoutingHelper("BS4 4NL")
         context = self.get_context_data(**kwargs)
         return self.render_to_response(context)
 
@@ -357,6 +357,7 @@ def get(self, request, *args, **kwargs):
                     kwargs={"postcode": self.postcode.without_space},
                 )
             )
+        kwargs["rh"] = rh
         context = self.get_context_data(**kwargs)
         return self.render_to_response(context)
 

polling_stations/settings/base.py

@@ -395,6 +395,7 @@ def repo_root(*x):
 from .constants.tiles import *  # noqa
 from .constants.uploads import *  # noqa
 
+
 # Import .local.py last - settings in local.py override everything else
 # only if we're not testing
 try:

polling_stations/settings/constants/elections.py

@@ -1,4 +1,5 @@
 import os
+from pathlib import Path
 
 EE_BASE = os.environ.get("EE_BASE", "https://elections.democracyclub.org.uk/")
 """
@@ -18,7 +19,15 @@
     "local.epping-forest.moreton-and-fyfield.by.2018-05-03"  # uncontested
 ]
 
-
 NEXT_CHARISMATIC_ELECTION_DATES = []
 
 SHOW_GB_ID_MESSAGING = True
+
+if data_path := os.environ.get("ELECTION_PARQUET_DATA_PATH", False):
+    ELECTION_PARQUET_DATA_PATH = Path(data_path)
+    USE_LOCAL_PARQUET_ELECTIONS = True
+WCIVF_BALLOT_CACHE_URL = (
+    "https://wcivf-ballot-cache.s3.eu-west-2.amazonaws.com/ballot_data/"
+)
+
+DEVS_DC_BASE = os.environ.get("DEVS_DC_BASE", "https://developers.democracyclub.org.uk")

polling_stations/settings/testing.py

@@ -2,7 +2,6 @@
 from dc_logging_client import DCWidePostcodeLoggingClient
 import os
 
-
 EVERY_ELECTION["CHECK"] = True  # noqa
 NEXT_CHARISMATIC_ELECTION_DATES = []
 DISABLE_GA = True  # don't log to Google Analytics when we are running tests
@@ -15,15 +14,13 @@
 GOOGLE_API_KEYS = []
 MAPBOX_API_KEY = ""
 
-
 STATICFILES_STORAGE = "pipeline.storage.PipelineStorage"
 
 RUNNING_TESTS = True
 
 POSTCODE_LOGGER = DCWidePostcodeLoggingClient(fake=True)
 EMAIL_BACKEND = "django.core.mail.backends.console.EmailBackend"
 
-
 os.environ["DJANGO_ALLOW_ASYNC_UNSAFE"] = "true"
 
 READ_ONLY_API_AUTH_TOKENS = [