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#!/usr/bin/python3
#----------------------------------------------------------------------
# Webmap CGI (Common Gateway Interface) for the Klimatanalys Norr project
# Copyright © 2025 Guilhem Moulin <info@guilhem.se>
#
# This program is free software: you can redistribute it and/or modify it
# under the terms of the GNU Affero General Public License as published by
# the Free Software Foundation, either version 3 of the License, or (at
# your option) any later version.
#
# This program is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Affero
# General Public License for more details.
#
# You should have received a copy of the GNU Affero General Public License
# along with this program. If not, see <https://www.gnu.org/licenses/>.
#----------------------------------------------------------------------
# pylint: disable=invalid-name, missing-module-docstring, fixme
# pylint: enable=invalid-name
import sys
from os import path as os_path
from json import load as json_load, JSONDecodeError
import logging
from typing import Final, Iterator
import atexit
from psycopg import connect, Cursor # pylint: disable=import-error
import common
def get_table_map() -> dict[tuple[str, str], str]:
"""Get mapping of pairs (MVT group name, layername) to table name."""
ret = {}
config = common.load_config()
layer_groups = config.get('layer-groups', {})
layers = config.get('layers', {})
layernames = set(layers.keys())
for groupname, patterns in layer_groups.items():
for layername in common.layers_in_group(groupname, patterns, layernames):
exportdef = layers[layername].get('publish', None)
if exportdef is None:
continue
if isinstance(exportdef, str):
exportdef = [ exportdef ]
for layername_mvt in exportdef:
k = (groupname, layername_mvt)
if k in ret:
raise RuntimeError(f'Duplicate key {k}')
ret[k] = layername
return ret
SCHEMA_NAME : Final[str] = 'postgis'
def get_query(layername : str) -> bytes:
"""Get GeoJSON-producing query for the given layer."""
# TODO don't hardcode geometry column name
# TODO[trixie]id_column => 'ogc_fid' (but don't hardcode either)
query = 'SELECT convert_to(ST_AsGeoJSON(m.*,'
query += 'geom_column=>\'wkb_geometry\','
query += 'pretty_bool=>\'f\'),'
query += '\'UTF8\') AS "GeoJSON" '
query += 'FROM ('
query += 'SELECT l.* '
query += 'FROM ' + common.escape_identifier(SCHEMA_NAME)
query += '.' + common.escape_identifier(layername) + ' l '
query += 'WHERE l.ogc_fid = %s'
query += ') m'
return query.encode('utf-8')
STATUS_OK : Final[str] = '200 OK'
STATUS_BAD_REQUEST : Final[str] = '400 Bad Request'
STATUS_NOT_ALLOWED : Final[str] = '405 Method Not Allowed'
STATUS_INTERNAL_SERVER_ERROR : Final[str] = '500 Internal Server Error'
EMPTY_RESPONSE_HEADERS : Final[list[tuple[str,str]]] = [
('Content-Type', 'text/plain'),
('Content-Length', '0'),
]
CONTENT_TYPE_JSON : Final[tuple[str,str]] = ('Content-Type', 'application/json; charset=UTF-8')
MAX_FEATURE_COUNT : Final[int] = 500
def application(env, start_response) -> Iterator[bytes]:
"""Main application."""
if env['REQUEST_METHOD'].upper() != 'POST':
logging.error('Invalid request method %s', env['REQUEST_METHOD'])
start_response(STATUS_NOT_ALLOWED, EMPTY_RESPONSE_HEADERS)
return
content_type = env.get('CONTENT_TYPE', '').lower()
if content_type != 'application/json' and not content_type.startswith('application/json;'):
logging.error('Invalid Content-Type: %s', content_type)
start_response(STATUS_BAD_REQUEST, EMPTY_RESPONSE_HEADERS)
return
first = True
try:
body = json_load(env['wsgi.input'])
if not isinstance(body, dict):
raise ValueError
start_response(STATUS_OK, [CONTENT_TYPE_JSON])
# pylint: disable-next=no-member
with PG_CONN.cursor(binary=True, scrollable=False, withhold=False) as cur:
if not isinstance(body, dict):
raise ValueError
mvt = body.get('mvt', None)
layername = body.get('layer', None)
if not isinstance(mvt, str) or not isinstance(layername, str):
raise ValueError
query = QUERY_MAP[TABLE_MAP[(mvt, layername)]]
fid = body.get('fid', None)
if not isinstance(fid, int):
raise ValueError
cur.execute(query, params=(fid,))
resp = cur.fetchone()
if resp is not None:
yield resp[0]
except (JSONDecodeError, LookupError, UnicodeDecodeError, ValueError) as exc:
logging.exception('Invalid request body')
# start_response(,,sys.exc_info()) should work here, but doesn't
# because of https://github.com/unbit/uwsgi/issues/2278
if first:
start_response(STATUS_BAD_REQUEST, EMPTY_RESPONSE_HEADERS)
else:
# headers already sent, can't do better; the client will get a 200 status
# code, but fail to parse the payload as JSON anyway
exc_info = sys.exc_info()
raise exc_info[1].with_traceback(exc_info[2]) from exc
except Exception as exc: # pylint: disable=broad-exception-caught
logging.exception('Internal Server Error')
if first:
start_response(STATUS_INTERNAL_SERVER_ERROR, EMPTY_RESPONSE_HEADERS)
else:
exc_info = sys.exc_info()
raise exc_info[1].with_traceback(exc_info[2]) from exc
# We could use a psycopg_pool.ConnectionPool() but that would be
# overkill since we only have 2 workers and no threads. So each worker
# simply opens a (single) connection to PostgreSQL at launch time.
# Use autocommit to avoid starting a transaction, cf.
# https://www.psycopg.org/psycopg3/docs/basic/transactions.html#autocommit-transactions
PG_CONN = connect('postgresql://webmap_guest@/webmap',
autocommit=True,
prepare_threshold=0,
# TODO[trixie] use cursor_factory=RawCursor
# https://www.psycopg.org/psycopg3/docs/advanced/cursors.html#cursor-types
cursor_factory=Cursor)
@atexit.register
def handler():
"""Gracefully close the connection before terminating the worker"""
# avoid "AttributeError: 'NoneType' object has no attribute 'connection_summary'"
# when destructing the object
# TODO[trixie] reevaluate, possibly related to https://github.com/psycopg/psycopg/issues/591
PG_CONN.close() # pylint: disable=no-member
common.init_logger(app=os_path.basename(__file__), level=logging.INFO)
TABLE_MAP : Final[dict[tuple[str, str], str]] = get_table_map()
QUERY_MAP : Final[dict[str,bytes]] = { lyr:get_query(lyr) for lyr in set(TABLE_MAP.values()) }
PG_CONN.execute( # pylint: disable=no-member
'SET search_path TO ' + common.escape_identifier(SCHEMA_NAME) + ',public',
prepare=False)
PG_CONN.execute( # pylint: disable=no-member
'SET statement_timeout TO 15000', # 15s
prepare=False)
del sys.modules['common']
del common
del get_query
del get_table_map
del os_path
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