# =================================================================
#
# Authors: Jorge Samuel Mendes de Jesus <jorge.dejesus@protonmail.com>
# Tom Kralidis <tomkralidis@gmail.com>
# Mary Bucknell <mbucknell@usgs.gov>
#
# Copyright (c) 2018 Jorge Samuel Mendes de Jesus
# Copyright (c) 2019 Tom Kralidis
#
# Permission is hereby granted, free of charge, to any person
# obtaining a copy of this software and associated documentation
# files (the "Software"), to deal in the Software without
# restriction, including without limitation the rights to use,
# copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the
# Software is furnished to do so, subject to the following
# conditions:
#
# The above copyright notice and this permission notice shall be
# included in all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
# OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
# HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
# WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
# FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
# OTHER DEALINGS IN THE SOFTWARE.
#
# =================================================================
# Testing local docker:
# docker run --name "postgis" \
# -v postgres_data:/var/lib/postgresql -p 5432:5432 \
# -e ALLOW_IP_RANGE=0.0.0.0/0 \
# -e POSTGRES_USER=postgres \
# -e POSTGRES_PASS=postgres \
# -e POSTGRES_DBNAME=test \
# -d -t kartoza/postgis
# Import dump:
# gunzip < tests/data/hotosm_bdi_waterways.sql.gz |
# psql -U postgres -h 127.0.0.1 -p 5432 test
import logging
import json
import psycopg2
from psycopg2.sql import SQL, Identifier, Literal
from pygeoapi.provider.base import BaseProvider, \
ProviderConnectionError, ProviderQueryError, ProviderItemNotFoundError
from psycopg2.extras import RealDictCursor
LOGGER = logging.getLogger(__name__)
[docs]class DatabaseConnection:
"""Database connection class to be used as 'with' statement.
The class returns a connection object.
"""
def __init__(self, conn_dic, table, context="query"):
"""
PostgreSQLProvider Class constructor returning
:param conn: dictionary with connection parameters
to be used by psycopg2
dbname – the database name (database is a deprecated alias)
user – user name used to authenticate
password – password used to authenticate
host – database host address
(defaults to UNIX socket if not provided)
port – connection port number
(defaults to 5432 if not provided)
search_path – search path to be used (by order) , normally
data is in the public schema, [public],
or in a specific schema ["osm", "public"].
Note: First we should have the schema
being used and then public
:param table: table name containing the data. This variable is used to
assemble column information
:param context: query or hits, if query then it will determine
table column otherwise will not do it
:returns: psycopg2.extensions.connection
"""
self.conn_dic = conn_dic
self.table = table
self.context = context
self.columns = None
self.fields = {} # Dict of columns. Key is col name, value is type
self.conn = None
def __enter__(self):
try:
search_path = self.conn_dic.pop('search_path', ['public'])
if search_path != ['public']:
self.conn_dic["options"] = '-c \
search_path={}'.format(",".join(search_path))
LOGGER.debug('Using search path: {} '.format(search_path))
self.conn = psycopg2.connect(**self.conn_dic)
self.conn.set_client_encoding('utf8')
except psycopg2.OperationalError:
LOGGER.error("Couldn't connect to Postgis using:{}".format(
str(self.conn_dic)))
raise ProviderConnectionError()
self.cur = self.conn.cursor()
if self.context == 'query':
# Getting columns
query_cols = "SELECT column_name, udt_name FROM information_schema.columns \
WHERE table_name = '{}' and udt_name != 'geometry';".format(
self.table)
self.cur.execute(query_cols)
result = self.cur.fetchall()
self.columns = SQL(', ').join(
[Identifier(item[0]) for item in result]
)
self.fields = dict(result)
return self
def __exit__(self, exc_type, exc_val, exc_tb):
# some logic to commit/rollback
self.conn.close()
[docs]class PostgreSQLProvider(BaseProvider):
"""Generic provider for Postgresql based on psycopg2
using sync approach and server side
cursor (using support class DatabaseCursor)
"""
def __init__(self, provider_def):
"""
PostgreSQLProvider Class constructor
:param provider_def: provider definitions from yml pygeoapi-config.
data,id_field, name set in parent class
data contains the connection information
for class DatabaseCursor
:returns: pygeoapi.provider.base.PostgreSQLProvider
"""
BaseProvider.__init__(self, provider_def)
self.table = provider_def['table']
self.id_field = provider_def['id_field']
self.conn_dic = provider_def['data']
self.geom = provider_def.get('geom_field', 'geom')
LOGGER.debug('Setting Postgresql properties:')
LOGGER.debug('Connection String:{}'.format(
",".join(("{}={}".format(*i) for i in self.conn_dic.items()))))
LOGGER.debug('Name:{}'.format(self.name))
LOGGER.debug('ID_field:{}'.format(self.id_field))
LOGGER.debug('Table:{}'.format(self.table))
LOGGER.debug('Get available fields/properties')
self.get_fields()
[docs] def get_fields(self):
"""
Get fields from PostgreSQL table (columns are field)
:returns: dict of fields
"""
if not self.fields:
with DatabaseConnection(self.conn_dic, self.table) as db:
self.fields = db.fields
return self.fields
def __get_where_clauses(self, properties=[], bbox=[]):
"""
Generarates WHERE conditions to be implemented in query.
Private method mainly associated with query method
:param properties: list of tuples (name, value)
:param bbox: bounding box [minx,miny,maxx,maxy]
:returns: psycopg2.sql.Composed or psycopg2.sql.SQL
"""
where_conditions = []
if properties:
property_clauses = [SQL('{} = {}').format(
Identifier(k), Literal(v)) for k, v in properties]
where_conditions += property_clauses
if bbox:
bbox_clause = SQL('{} && ST_MakeEnvelope({})').format(
Identifier(self.geom), SQL(', ').join(
[Literal(bbox_coord) for bbox_coord in bbox]))
where_conditions.append(bbox_clause)
if where_conditions:
where_clause = SQL(' WHERE {}').format(
SQL(' AND ').join(where_conditions))
else:
where_clause = SQL('')
return where_clause
[docs] def query(self, startindex=0, limit=10, resulttype='results',
bbox=[], datetime_=None, properties=[], sortby=[],
select_properties=[], skip_geometry=False):
"""
Query Postgis for all the content.
e,g: http://localhost:5000/collections/hotosm_bdi_waterways/items?
limit=1&resulttype=results
:param startindex: starting record to return (default 0)
:param limit: number of records to return (default 10)
:param resulttype: return results or hit limit (default results)
:param bbox: bounding box [minx,miny,maxx,maxy]
:param datetime_: temporal (datestamp or extent)
:param properties: list of tuples (name, value)
:param sortby: list of dicts (property, order)
:param select_properties: list of property names
:param skip_geometry: bool of whether to skip geometry (default False)
:returns: GeoJSON FeaturesCollection
"""
LOGGER.debug('Querying PostGIS')
if resulttype == 'hits':
with DatabaseConnection(self.conn_dic,
self.table, context="hits") as db:
cursor = db.conn.cursor(cursor_factory=RealDictCursor)
where_clause = self.__get_where_clauses(
properties=properties, bbox=bbox)
sql_query = SQL("SELECT COUNT(*) as hits from {} {}").\
format(Identifier(self.table), where_clause)
try:
cursor.execute(sql_query)
except Exception as err:
LOGGER.error('Error executing sql_query: {}: {}'.format(
sql_query.as_string(cursor), err))
raise ProviderQueryError()
hits = cursor.fetchone()["hits"]
return self.__response_feature_hits(hits)
end_index = startindex + limit
with DatabaseConnection(self.conn_dic, self.table) as db:
cursor = db.conn.cursor(cursor_factory=RealDictCursor)
where_clause = self.__get_where_clauses(
properties=properties, bbox=bbox)
sql_query = SQL("DECLARE \"geo_cursor\" CURSOR FOR \
SELECT DISTINCT {},ST_AsGeoJSON({}) FROM {}{}").\
format(db.columns,
Identifier(self.geom),
Identifier(self.table),
where_clause)
LOGGER.debug('SQL Query: {}'.format(sql_query.as_string(cursor)))
LOGGER.debug('Start Index: {}'.format(startindex))
LOGGER.debug('End Index: {}'.format(end_index))
try:
cursor.execute(sql_query)
for index in [startindex, limit]:
cursor.execute("fetch forward {} from geo_cursor"
.format(index))
except Exception as err:
LOGGER.error('Error executing sql_query: {}'.format(
sql_query.as_string(cursor)))
LOGGER.error(err)
raise ProviderQueryError()
row_data = cursor.fetchall()
feature_collection = {
'type': 'FeatureCollection',
'features': []
}
for rd in row_data:
feature_collection['features'].append(
self.__response_feature(rd))
return feature_collection
[docs] def get_previous(self, cursor, identifier):
"""
Query previous ID given current ID
:param identifier: feature id
:returns: feature id
"""
sql = 'SELECT {} AS id FROM {} WHERE {}<%s ORDER BY {} DESC LIMIT 1'
cursor.execute(SQL(sql).format(
Identifier(self.id_field),
Identifier(self.table),
Identifier(self.id_field),
Identifier(self.id_field),
), (identifier,))
item = cursor.fetchall()
id_ = item[0]['id'] if item else identifier
return id_
[docs] def get_next(self, cursor, identifier):
"""
Query next ID given current ID
:param identifier: feature id
:returns: feature id
"""
sql = 'SELECT {} AS id FROM {} WHERE {}>%s ORDER BY {} LIMIT 1'
cursor.execute(SQL(sql).format(
Identifier(self.id_field),
Identifier(self.table),
Identifier(self.id_field),
Identifier(self.id_field),
), (identifier,))
item = cursor.fetchall()
id_ = item[0]['id'] if item else identifier
return id_
[docs] def get(self, identifier):
"""
Query the provider for a specific
feature id e.g: /collections/hotosm_bdi_waterways/items/13990765
:param identifier: feature id
:returns: GeoJSON FeaturesCollection
"""
LOGGER.debug('Get item from Postgis')
with DatabaseConnection(self.conn_dic, self.table) as db:
cursor = db.conn.cursor(cursor_factory=RealDictCursor)
sql_query = SQL("SELECT {},ST_AsGeoJSON({}) \
from {} WHERE {}=%s").format(db.columns,
Identifier(self.geom),
Identifier(self.table),
Identifier(self.id_field))
LOGGER.debug('SQL Query: {}'.format(sql_query.as_string(db.conn)))
LOGGER.debug('Identifier: {}'.format(identifier))
try:
cursor.execute(sql_query, (identifier, ))
except Exception as err:
LOGGER.error('Error executing sql_query: {}'.format(
sql_query.as_string(cursor)))
LOGGER.error(err)
raise ProviderQueryError()
results = cursor.fetchall()
row_data = None
if results:
row_data = results[0]
feature = self.__response_feature(row_data)
if feature:
feature['prev'] = self.get_previous(cursor, identifier)
feature['next'] = self.get_next(cursor, identifier)
return feature
else:
err = 'item {} not found'.format(identifier)
LOGGER.error(err)
raise ProviderItemNotFoundError(err)
def __response_feature(self, row_data):
"""
Assembles GeoJSON output from DB query
:param row_data: DB row result
:returns: `dict` of GeoJSON Feature
"""
if row_data:
rd = dict(row_data)
feature = {
'type': 'Feature'
}
feature["geometry"] = json.loads(
rd.pop('st_asgeojson'))
feature['properties'] = rd
feature['id'] = feature['properties'].get(self.id_field)
return feature
else:
return None
def __response_feature_hits(self, hits):
"""Assembles GeoJSON/Feature number
e.g: http://localhost:5000/collections/
hotosm_bdi_waterways/items?resulttype=hits
:returns: GeoJSON FeaturesCollection
"""
feature_collection = {"features": [],
"type": "FeatureCollection"}
feature_collection['numberMatched'] = hits
return feature_collection