+# SPDX-License-Identifier: GPL-2.0-only
+#
+# This file is part of Nominatim. (https://nominatim.org)
+#
+# Copyright (C) 2022 by the Nominatim developer community.
+# For a full list of authors see the git log.
"""
Specialised connection and cursor functions.
"""
+from typing import Optional, Any, Callable, ContextManager, Dict, cast, overload, Tuple, Iterable
import contextlib
import logging
import os
import psycopg2
import psycopg2.extensions
import psycopg2.extras
+from psycopg2 import sql as pysql
+from nominatim.typing import SysEnv, Query, T_cursor
from nominatim.errors import UsageError
LOG = logging.getLogger()
-class _Cursor(psycopg2.extras.DictCursor):
+class Cursor(psycopg2.extras.DictCursor):
""" A cursor returning dict-like objects and providing specialised
execution functions.
"""
-
- def execute(self, query, args=None): # pylint: disable=W0221
+ # pylint: disable=arguments-renamed,arguments-differ
+ def execute(self, query: Query, args: Any = None) -> None:
""" Query execution that logs the SQL query when debugging is enabled.
"""
- LOG.debug(self.mogrify(query, args).decode('utf-8'))
+ if LOG.isEnabledFor(logging.DEBUG):
+ LOG.debug(self.mogrify(query, args).decode('utf-8'))
super().execute(query, args)
- def scalar(self, sql, args=None):
+
+ def execute_values(self, sql: Query, argslist: Iterable[Tuple[Any, ...]],
+ template: Optional[Query] = None) -> None:
+ """ Wrapper for the psycopg2 convenience function to execute
+ SQL for a list of values.
+ """
+ LOG.debug("SQL execute_values(%s, %s)", sql, argslist)
+
+ psycopg2.extras.execute_values(self, sql, argslist, template=template)
+
+
+ def scalar(self, sql: Query, args: Any = None) -> Any:
""" Execute query that returns a single value. The value is returned.
If the query yields more than one row, a ValueError is raised.
"""
if self.rowcount != 1:
raise RuntimeError("Query did not return a single row.")
- return self.fetchone()[0]
+ result = self.fetchone()
+ assert result is not None
+
+ return result[0]
+
+
+ def drop_table(self, name: str, if_exists: bool = True, cascade: bool = False) -> None:
+ """ Drop the table with the given name.
+ Set `if_exists` to False if a non-existent table should raise
+ an exception instead of just being ignored. If 'cascade' is set
+ to True then all dependent tables are deleted as well.
+ """
+ sql = 'DROP TABLE '
+ if if_exists:
+ sql += 'IF EXISTS '
+ sql += '{}'
+ if cascade:
+ sql += ' CASCADE'
+
+ self.execute(pysql.SQL(sql).format(pysql.Identifier(name)))
-class _Connection(psycopg2.extensions.connection):
+class Connection(psycopg2.extensions.connection):
""" A connection that provides the specialised cursor by default and
adds convenience functions for administrating the database.
"""
+ @overload # type: ignore[override]
+ def cursor(self) -> Cursor:
+ ...
+
+ @overload
+ def cursor(self, name: str) -> Cursor:
+ ...
- def cursor(self, cursor_factory=_Cursor, **kwargs):
+ @overload
+ def cursor(self, cursor_factory: Callable[..., T_cursor]) -> T_cursor:
+ ...
+
+ def cursor(self, cursor_factory = Cursor, **kwargs): # type: ignore
""" Return a new cursor. By default the specialised cursor is returned.
"""
return super().cursor(cursor_factory=cursor_factory, **kwargs)
- def table_exists(self, table):
+ def table_exists(self, table: str) -> bool:
""" Check that a table with the given name exists in the database.
"""
with self.cursor() as cur:
num = cur.scalar("""SELECT count(*) FROM pg_tables
WHERE tablename = %s and schemaname = 'public'""", (table, ))
- return num == 1
+ return num == 1 if isinstance(num, int) else False
+
+
+ def table_has_column(self, table: str, column: str) -> bool:
+ """ Check if the table 'table' exists and has a column with name 'column'.
+ """
+ with self.cursor() as cur:
+ has_column = cur.scalar("""SELECT count(*) FROM information_schema.columns
+ WHERE table_name = %s
+ and column_name = %s""",
+ (table, column))
+ return has_column > 0 if isinstance(has_column, int) else False
- def index_exists(self, index, table=None):
+ def index_exists(self, index: str, table: Optional[str] = None) -> bool:
""" Check that an index with the given name exists in the database.
If table is not None then the index must relate to the given
table.
if table is not None:
row = cur.fetchone()
+ if row is None or not isinstance(row[0], str):
+ return False
return row[0] == table
return True
- def drop_table(self, name, if_exists=True):
+ def drop_table(self, name: str, if_exists: bool = True, cascade: bool = False) -> None:
""" Drop the table with the given name.
- Set `if_exists` to False if a non-existant table should raise
+ Set `if_exists` to False if a non-existent table should raise
an exception instead of just being ignored.
"""
with self.cursor() as cur:
- cur.execute("""DROP TABLE {} "{}"
- """.format('IF EXISTS' if if_exists else '', name))
+ cur.drop_table(name, if_exists, cascade)
self.commit()
- def server_version_tuple(self):
+ def server_version_tuple(self) -> Tuple[int, int]:
""" Return the server version as a tuple of (major, minor).
Converts correctly for pre-10 and post-10 PostgreSQL versions.
"""
version = self.server_version
if version < 100000:
- return (int(version / 10000), (version % 10000) / 100)
+ return (int(version / 10000), int((version % 10000) / 100))
return (int(version / 10000), version % 10000)
- def postgis_version_tuple(self):
+ def postgis_version_tuple(self) -> Tuple[int, int]:
""" Return the postgis version installed in the database as a
tuple of (major, minor). Assumes that the PostGIS extension
has been installed already.
with self.cursor() as cur:
version = cur.scalar('SELECT postgis_lib_version()')
- return tuple((int(x) for x in version.split('.')[:2]))
+ version_parts = version.split('.')
+ if len(version_parts) < 2:
+ raise UsageError(f"Error fetching Postgis version. Bad format: {version}")
+ return (int(version_parts[0]), int(version_parts[1]))
+
+class ConnectionContext(ContextManager[Connection]):
+ """ Context manager of the connection that also provides direct access
+ to the underlying connection.
+ """
+ connection: Connection
-def connect(dsn):
+def connect(dsn: str) -> ConnectionContext:
""" Open a connection to the database using the specialised connection
factory. The returned object may be used in conjunction with 'with'.
When used outside a context manager, use the `connection` attribute
to get the connection.
"""
try:
- conn = psycopg2.connect(dsn, connection_factory=_Connection)
- ctxmgr = contextlib.closing(conn)
+ conn = psycopg2.connect(dsn, connection_factory=Connection)
+ ctxmgr = cast(ConnectionContext, contextlib.closing(conn))
ctxmgr.connection = conn
return ctxmgr
except psycopg2.OperationalError as err:
- raise UsageError("Cannot connect to database: {}".format(err)) from err
+ raise UsageError(f"Cannot connect to database: {err}") from err
# Translation from PG connection string parameters to PG environment variables.
}
-def get_pg_env(dsn, base_env=None):
+def get_pg_env(dsn: str,
+ base_env: Optional[SysEnv] = None) -> Dict[str, str]:
""" Return a copy of `base_env` with the environment variables for
PostgresSQL set up from the given database connection string.
If `base_env` is None, then the OS environment is used as a base
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