[UK] May 2025 Boundary-Line import.

And NIE update script from 2024 general election.

Author: dracos

mapit_gb/controls/2025-05.py

@@ -0,0 +1,110 @@
+# A control file for importing Boundary-Line.
+# CEDs (county council electoral divisions) don't have ONS codes, so we have to
+# have something manual as this is a year of county council boundary changes.
+#
+# OS release notes are at https://docs.os.uk/os-downloads/addressing-and-location/boundary-line/release-notes/may-2025
+#
+# The following English counties have had full boundary changes:
+# Derbyshire - https://www.legislation.gov.uk/uksi/2024/1189/contents/made
+# Gloucestershire - https://www.legislation.gov.uk/uksi/2025/34/contents/made
+# Oxfordshire - https://www.legislation.gov.uk/uksi/2025/33/contents/made
+# Staffordshire - https://www.legislation.gov.uk/uksi/2024/1184/contents/made
+# Worcestershire - https://www.legislation.gov.uk/uksi/2024/1176/contents/made
+#
+# Unitaries with boundary changes are the following, but we spot them
+# automatically by GSS code: Buckinghamshire, Durham, North Northamptonshire,
+# Northumberland, Shropshire, West Northamptonshire
+
+from mapit.models import Area, Generation, CodeType
+
+COUNTIES_CHANGED = ["%s County Council" % c for c in [
+    'Derbyshire', 'Gloucestershire', 'Oxfordshire', 'Staffordshire', 'Worcestershire'
+]]
+COUNTIES_NOT_CHANGED = ["%s County Council" % c for c in [
+    'Cambridgeshire', 'Devon', 'Dorset', 'East Sussex', 'Essex', 'Hampshire',
+    'Hertfordshire', 'Kent', 'Lancashire', 'Leicestershire', 'Lincolnshire',
+    "Norfolk", "Northamptonshire", "North Yorkshire", 'Nottinghamshire',
+    "Somerset", "Suffolk", "Surrey", 'Warwickshire', 'West Sussex'
+]]
+
+
+def code_version():
+    return 'gss'
+
+
+def check(name, type, country, geometry, ons_code, commit, **args):
+    """Should return True if this area is NEW, False if we should match against
+    an ONS/unit_id code, or an Area to be used as an override instead."""
+
+    current = Generation.objects.current()
+    if not current:  # Fresh import
+        return False
+
+    # The boundary between Maidstone Rural West and Maidstone Central is
+    # incorrect (the release notes say they did not get the fixed amendment in
+    # in time). There was a change, but a much smaller one than what is
+    # incorrectly included, so better to keep the old boundaries, as less wrong
+    if type == 'CED' and name in ('Maidstone Rural West ED', 'Maidstone Central ED'):
+        return 'SKIP'
+
+    # Another repeat of 2012-05/2013-10/2018-05/2019-05 comments; still nothing
+    # has changed, I'm doing the dance the same as last time.
+
+    # There is a problem, in that users of this service, including ourselves,
+    # have assumed a mapit ID is an identifier for a concept, rather than a
+    # particular boundary. Until now, this has not really been an issue, but
+    # this edition of Boundary-Line changes the boundary of two councils,
+    # assigning them new ONS IDs in the process. This would cause some amount
+    # of pain for code that assumes e.g. ID 2579 is the concept of Glasgow City
+    # Council, rather than the boundary of Glasgow City Council from
+    # generations 1 to 16 (but then not 17).
+    #
+    # Therefore, for the time being, we have decided to match up the new
+    # boundaries with the current mapit IDs for these four councils.
+    #
+    # In the future, perhaps the current IDs should host the concept, for
+    # continuity, and the current and historical boundaries are then available
+    # under it in some way. Tricky.
+
+    if type == 'MTD' and name in ('Barnsley District (B)', 'Sheffield District (B)'):
+        # 1. Create a deep copy of the existing area with a new ID
+        area = Area.objects.get(
+            names__name=name, names__type__code='O', generation_low__lte=current, generation_high__gte=current)
+        area_id = area.id
+        area_polygons = list(area.polygons.all())
+        area_codes = list(area.codes.all())
+        area_names = list(area.names.all())
+        area.pk = None
+        if commit:
+            area.save()
+            for data in [area_polygons, area_codes, area_names]:
+                for thing in data:
+                    thing.pk = None
+                    thing.area = area
+                    thing.save()
+
+        # 2. Update the existing area with the new boundary/generation IDs
+        area = Area.objects.get(id=area_id)
+        new_generation = Generation.objects.new()
+        area.generation_low = new_generation
+        if commit:
+            area.save()
+            # Delete the old ONS code because that only applies to the old boundary
+            area.codes.filter(type=CodeType.objects.get(code='ons')).delete()
+            # Update the GSS code because it's what the main script will then use, oddly.
+            area.codes.update_or_create(type=CodeType.objects.get(code='gss'), defaults={'code': ons_code})
+
+        return area
+
+    # Some UTAs have had boundary changes, but have ONS codes and so can be
+    # ignored/ detected that way.
+    if type != 'CED':
+        return False
+
+    # Make sure CEDs are loaded *after* CTY
+    area_within = Area.objects.filter(type__code='CTY', polygons__polygon__contains=geometry.geos.point_on_surface)[0]
+    if area_within.name in COUNTIES_CHANGED:
+        return True
+    elif area_within.name in COUNTIES_NOT_CHANGED:
+        return False
+    raise Exception("Bad county name given: %s" % area_within.name)

mapit_gb/management/commands/mapit_UK_2025_update_nie.py

@@ -0,0 +1,37 @@
+# This script is to be run as a one-off after the 2024 UK General Election
+# to update the Northern Ireland Assembly boundaries to match the UK
+# constituencies, as per section 33 of the Northern Ireland Act 1998.
+
+from django.core.management.base import BaseCommand
+from mapit.models import Area, Generation, Type
+
+
+def save(obj, options, space=''):
+    obj.pk = None
+    if options['commit']:
+        obj.save()
+    print(space, obj)
+
+
+class Command(BaseCommand):
+    help = 'Update the NI Assembly constituencies after the 2024 election'
+
+    def add_arguments(self, parser):
+        parser.add_argument('--commit', action='store_true', dest='commit', help='Actually update the database')
+
+    def handle(self, **options):
+        areas = Area.objects.filter(type__code='WMC', country__code='N', generation__high=Generation.objects.current())
+        nie_type = Type.objects.get(code='NIE')
+        generation = Generation.objects.new()
+        for area in areas:
+            polygons = list(area.polygons.all())
+            names = list(area.names.all())
+            codes = list(area.codes.all())
+            area.type = nie_type
+            area.generation_low_id = generation
+            area.generation_high_id = generation
+            save(area, options)
+            for data in [polygons, names, codes]:
+                for obj in data:
+                    obj.area = area
+                    save(obj, options, '  ')

mapit_gb/management/commands/mapit_UK_import_boundary_line.py

@@ -63,6 +63,8 @@ def handle_label(self, filename, **options):
                 ons_code = patch['ons-code']
             elif 'unit-id' in patch:
                 unit_id = patch['unit-id']
+            elif 'name' in patch:
+                name = patch['name']
 
             if area_code == 'NCP':
                 continue  # Ignore Non Parished Areas
@@ -220,4 +222,8 @@ def patch_boundary_line(self, name, ons_code, unit_id, area_code):
         if area_code == 'DIW' and name == 'Loughton Fairmead Ward' and ons_code == 'E05015731':
             return {'ons-code': 'E05015730'}
 
+        # Tewkesbury is *not* renaming, May 2025 has renamed it
+        if name == 'North Gloucestershire District (B)' and ons_code == 'E07000083':
+            return {'name': 'Tewkesbury District (B)'}
+
         return {}