304 lines
12 KiB
Python
304 lines
12 KiB
Python
# backend.py
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# openeventdatabase
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from datetime import datetime
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import json
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import os
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import re
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import subprocess
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import falcon
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import psycopg2
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import psycopg2.extras
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def db_connect():
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return psycopg2.connect(
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dbname=os.getenv("DB_NAME", "oedb"),
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host=os.getenv("DB_HOST", None),
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password=os.getenv("POSTGRES_PASSWORD", None),
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user=os.getenv("DB_USER", None))
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class EventEncoder(json.JSONEncoder):
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def default(self, o):
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if isinstance(o, datetime):
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return o.isoformat()
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try:
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return super().default(o)
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except TypeError:
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return str(o)
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def dumps(data):
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return json.dumps(data, cls=EventEncoder, sort_keys=True)
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class HeaderMiddleware:
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def process_response(self, req, resp, resource):
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resp.set_header('X-Powered-By', 'OpenEventDatabase')
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resp.set_header('Access-Control-Allow-Origin', '*')
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resp.set_header('Access-Control-Allow-Headers', 'X-Requested-With')
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resp.set_header('Access-Control-Allow-Headers', 'Content-Type')
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class StatsResource(object):
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def on_get(self, req, resp):
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db = db_connect()
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cur = db.cursor(cursor_factory=psycopg2.extras.DictCursor)
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# estimated row count, way faster then count(*)
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cur.execute("SELECT reltuples FROM pg_class r WHERE relname = 'events';")
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count = cur.fetchone()[0]
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cur.execute("SELECT max(lastupdate) as last_updated, current_timestamp-pg_postmaster_start_time() from events;")
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pg_stats = cur.fetchone()
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last = pg_stats[0]
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pg_uptime = pg_stats[1]
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uptime = subprocess.check_output(["uptime","-p"]).decode('utf-8')[0:-1]
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cur.close()
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db.close()
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resp.body = dumps(dict(events_count=count, last_updated=last, uptime=uptime, db_uptime=pg_uptime))
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resp.status = falcon.HTTP_200
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class BaseEvent:
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def row_to_feature(self, row):
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properties = dict(row['events_tags'])
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properties.update({
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'createdate': row['createdate'],
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'lastupdate': row['lastupdate'],
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'lon': row['lon'],
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'lat': row['lat'],
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"id": row['events_id']
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})
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if "distance" in row:
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properties['distance'] = row['distance']
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return {
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"type": "Feature",
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"geometry": json.loads(row['geometry']),
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"properties": properties
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}
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def rows_to_collection(self, rows):
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return {
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"type": "FeatureCollection",
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"features": [self.row_to_feature(r) for r in rows],
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"count": len(rows)
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}
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class EventsResource(BaseEvent):
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def on_get(self, req, resp):
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db = db_connect()
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cur = db.cursor(cursor_factory=psycopg2.extras.DictCursor)
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cur.execute("SELECT events_id, events_tags, createdate, lastupdate, st_asgeojson(geom) as geometry FROM events JOIN geo ON (hash=events_geo)")
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resp.body = dumps(self.rows_to_collection(cur.fetchall()))
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resp.status = falcon.HTTP_200
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class EventResource(BaseEvent):
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def maybe_insert_geometry(self, geometry, cur):
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# insert into geo table if not existing
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cur.execute("""INSERT INTO geo (hash, geom, geom_center) SELECT *, st_centroid(geom) FROM (SELECT md5(ewkt) as hash, st_setsrid(st_geomfromewkt(ewkt),4326) as geom FROM (SELECT st_asewkt(st_geomfromgeojson( %s )) as ewkt) as g) as i ON CONFLICT DO NOTHING RETURNING hash;""", (geometry,))
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# get its id (md5 hash)
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h = cur.fetchone()
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if h is None:
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cur.execute("""SELECT md5(st_asewkt(st_geomfromgeojson( %s )));""", (geometry,))
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h = cur.fetchone()
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return h
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def relative_time(self, when, cur):
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when = when.upper().replace(' ','+')
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event_start = cur.mogrify("%s",(when,)).decode("utf-8")
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event_stop = cur.mogrify("%s",(when,)).decode("utf-8")
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if when == 'NOW':
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event_start = "now()"
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event_stop = "now()"
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if when == 'TODAY':
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event_start = "CURRENT_DATE"
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event_stop = "CURRENT_DATE + INTERVAL '1 DAY'"
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if when == 'TOMORROW':
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event_start = "CURRENT_DATE + INTERVAL '1 DAY'"
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event_stop = "CURRENT_DATE + INTERVAL '2 DAY'"
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if when == 'YESTERDAY':
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event_start = "CURRENT_DATE - INTERVAL '1 DAY'"
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event_stop = "CURRENT_DATE"
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m = re.match('(LAST|NEXT)(YEAR|MONTH|WEEK|DAY|HOUR|MINUTE)',when)
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if m is not None:
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when = m.group(1)+'1'+m.group(2)+'S'
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m = re.match('(LAST|NEXT)([0-9]*)(YEAR|MONTH|WEEK|MINUTE|HOUR|DAY)S',when)
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if m is not None:
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if m.group(1) == 'LAST':
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event_start = "now() - INTERVAL '%s %s'" % m.group(2,3)
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event_stop = "now()"
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else:
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event_start = "now()"
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event_stop = "now() + INTERVAL '%s %s'" % m.group(2,3)
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return event_start, event_stop
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def on_get(self, req, resp, id=None):
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db = db_connect()
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cur = db.cursor(cursor_factory=psycopg2.extras.DictCursor)
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if id is None:
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# get query search parameters
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if 'bbox' in req.params:
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# limit search with bbox (E,S,W,N)
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event_bbox = cur.mogrify(" AND geom && ST_SetSRID(ST_MakeBox2D(ST_Point(%s,%s),ST_Point(%s,%s)),4326) ",tuple(req.params['bbox'])).decode("utf-8")
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event_dist = ""
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elif 'near' in req.params:
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# Limit search with location+distance
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# (long, lat, distance in meters)
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if len(req.params['near']) < 3:
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dist = 1
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else:
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dist = req.params['near'][2]
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event_bbox = cur.mogrify(" AND ST_Intersects(geom, ST_Buffer(st_setsrid(st_makepoint(%s,%s),4326)::geography,%s)::geometry) ", (req.params['near'][0], req.params['near'][1], dist)).decode("utf-8")
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event_dist = cur.mogrify("ST_Length(ST_ShortestLine(geom, st_setsrid(st_makepoint(%s,%s),4326))::geography)::integer as distance,", (req.params['near'][0], req.params['near'][1])).decode("utf-8")
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else:
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event_bbox = ""
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event_dist = ""
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if 'when' in req.params:
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# limit search with fixed time
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when = req.params['when'].upper()
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event_when = "tstzrange(%s,%s,'[]')" % (self.relative_time(when,cur))
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elif 'start' in req.params and 'stop' in req.params:
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# limit search with fixed time (start to stop)
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event_start, unused = self.relative_time(req.params['start'],cur)
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unused, event_stop = self.relative_time(req.params['stop'],cur)
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event_when = "tstzrange(%s,%s,'[]')" % (event_start, event_stop)
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elif 'start' in req.params and 'stop' not in req.params:
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# limit search with fixed time (start to now)
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event_start, unused = self.relative_time(req.params['start'],cur)
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event_when = "tstzrange(%s,now(),'[]')" % event_start
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elif 'start' not in req.params and 'stop' in req.params:
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# limit search with fixed time (now to stop)
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unused, event_stop = self.relative_time(req.params['stop'],cur)
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event_when = "tstzrange(now(),%s,'[]')" % event_stop
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else:
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event_when = "tstzrange(now(),now(),'[]')"
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if 'what' in req.params:
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# limit search based on "what"
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event_what = cur.mogrify(" AND events_what LIKE %s ", (req.params['what']+"%",)).decode("utf-8")
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else:
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event_what = ""
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if 'type' in req.params:
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# limit search based on type (scheduled, forecast, unscheduled)
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event_type = cur.mogrify(" AND events_type = %s ", (req.params['type'],)).decode("utf-8")
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else:
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event_type = ""
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if 'limit' in req.params:
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limit = cur.mogrify("LIMIT %s", (req.params['limit'],)).decode("utf-8")
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else:
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limit = "LIMIT 200"
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event_geom = "geom_center"
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if 'geom' in req.params:
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if req.params['geom'] == 'full':
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event_geom = "geom"
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else:
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event_geom = cur.mogrify("ST_SnapToGrid(geom,%s)",(req.params['geom'],)).decode("utf-8")
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# Search recent active events.
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sql = """SELECT events_id, events_tags, createdate, lastupdate, {event_dist} st_asgeojson({event_geom}) as geometry, st_x(geom_center) as lon, st_y(geom_center) as lat FROM events JOIN geo ON (hash=events_geo) {event_bbox} WHERE events_when && {event_when} {event_what} {event_type} ORDER BY createdate DESC {limit}"""
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# No user generated content here, so format is safe.
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sql = sql.format(event_dist=event_dist, event_geom=event_geom,
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event_bbox=event_bbox, event_what=event_what,
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event_when=event_when, event_type=event_type, limit=limit)
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cur.execute(sql)
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resp.body = dumps(self.rows_to_collection(cur.fetchall()))
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resp.status = falcon.HTTP_200
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else:
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# Get single event geojson Feature by id.
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cur.execute("SELECT events_id, events_tags, createdate, lastupdate, st_asgeojson(geom) as geometry, st_x(geom_center) as lon, st_y(geom_center) as lat FROM events JOIN geo ON (hash=events_geo) WHERE events_id=%s", [id])
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e = cur.fetchone()
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if e is not None:
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resp.body = dumps(self.row_to_feature(e))
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resp.status = falcon.HTTP_200
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else:
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resp.status = falcon.HTTP_404
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db.close()
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def insert_or_update(self, req, resp, id, query):
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# get request body payload (geojson Feature)
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body = req.stream.read().decode('utf-8')
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j = json.loads(body)
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if "properties" not in j or "geometry" not in j:
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resp.body = "missing 'geometry' or 'properties' elements"
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resp.status = falcon.HTTP_400
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if "start" not in j['properties']:
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event_start = j['properties']['when']
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else:
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event_start = j['properties']['start']
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if "stop" not in j['properties']:
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event_stop = j['properties']['when']
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else:
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event_stop = j['properties']['stop']
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if event_start == event_stop:
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bounds = '[]'
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else:
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bounds = '[)'
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# connect to db and insert
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db = db_connect()
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cur = db.cursor()
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# get the geometry part
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geometry=dumps(j['geometry'])
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h = self.maybe_insert_geometry(geometry,cur)
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params = (j['properties']['type'], j['properties']['what'], event_start, event_stop, bounds, dumps(j['properties']), h[0])
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if id:
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params = params + (id,)
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cur.execute(query, params)
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# get newly created event id
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e = cur.fetchone()
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db.commit()
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cur.close()
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db.close()
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# send back to client
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if e is None:
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resp.status = falcon.HTTP_409
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else:
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resp.body = """{"id":"%s"}""" % (e[0])
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resp.status = falcon.HTTP_201
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def on_post(self, req, resp):
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self.insert_or_update(req, resp, None, """INSERT INTO events ( events_type, events_what, events_when, events_tags, events_geo) VALUES (%s, %s, tstzrange(%s,%s,%s) , %s, %s) ON CONFLICT DO NOTHING RETURNING events_id;""")
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def on_put(self, req, resp, id):
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self.insert_or_update(req, resp, id, """UPDATE events SET ( events_type, events_what, events_when, events_tags, events_geo) = (%s, %s, tstzrange(%s,%s,%s) , %s, %s) WHERE events_id = %s RETURNING events_id;""")
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def on_delete(self, req, resp, id):
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db = db_connect()
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cur = db.cursor()
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cur.execute("""DELETE FROM events WHERE events_id = %s;""", (id,));
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db.commit()
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cur.close()
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db.close()
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if cur.rowcount:
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resp.status = falcon.HTTP_204
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else:
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resp.status = falcon.HTTP_404
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# Falcon.API instances are callable WSGI apps.
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app = falcon.API(middleware=[HeaderMiddleware()])
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# Resources are represented by long-lived class instances
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events = EventsResource()
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event = EventResource()
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stats = StatsResource()
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# things will handle all requests to the matching URL path
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app.add_route('/events', events)
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app.add_route('/event/{id}', event) # handle single event requests
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app.add_route('/event', event) # handle single event requests
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app.add_route('/stats', stats)
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