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Source code for temporal.core

"""
This module provides the functionality to create the temporal
SQL database and to establish a connection to the database.

Usage:

.. code-block:: python

    >>> import grass.temporal as tgis
    >>> # Create the temporal database
    >>> tgis.init()
    >>> # Establish a database connection
    >>> dbif, connected = tgis.init_dbif(None)
    >>> dbif.connect()
    >>> # Execute a SQL statement
    >>> dbif.execute_transaction("SELECT datetime(0, 'unixepoch', 'localtime');")
    >>> # Mogrify an SQL statement
    >>> dbif.mogrify_sql_statement(["SELECT name from raster_base where name = ?",
    ... ("precipitation",)])
    "SELECT name from raster_base where name = 'precipitation'"
    >>> dbif.close()


(C) 2011-2014 by the GRASS Development Team
This program is free software under the GNU General Public
License (>=v2). Read the file COPYING that comes with GRASS
for details.

:author: Soeren Gebbert
"""
#import traceback
import os
import sys
import grass.script as gscript
# i18N
import gettext
gettext.install('grasslibs', os.path.join(os.getenv("GISBASE"), 'locale'))

if sys.version_info.major == 3:
    long = int

from .c_libraries_interface import *
from grass.pygrass import messages
# Import all supported database backends
# Ignore import errors since they are checked later
try:
    import sqlite3
except ImportError:
    pass
# Postgresql is optional, existence is checked when needed
try:
    import psycopg2
    import psycopg2.extras
except:
    pass

import atexit
from datetime import datetime

###############################################################################


[docs]def profile_function(func): """Profiling function provided by the temporal framework""" do_profiling = os.getenv("GRASS_TGIS_PROFILE") if do_profiling is "True" or do_profiling is "1": import cProfile, pstats try: import StringIO as io except ImportError: import io pr = cProfile.Profile() pr.enable() func() pr.disable() s = io.StringIO() sortby = 'cumulative' ps = pstats.Stats(pr, stream=s).sort_stats(sortby) ps.print_stats() print(s.getvalue()) else: func() # Global variable that defines the backend # of the temporal GIS # It can either be "sqlite" or "pg"
tgis_backend = None
[docs]def get_tgis_backend(): """Return the temporal GIS backend as string :returns: either "sqlite" or "pg" """ global tgis_backend return tgis_backend # Global variable that defines the database string # of the temporal GIS
tgis_database = None
[docs]def get_tgis_database(): """Return the temporal database string specified with t.connect """ global tgis_database return tgis_database # The version of the temporal framework # this value must be an integer larger than 0 # Increase this value in case of backward incompatible changes in the TGIS API
tgis_version = 2 # The version of the temporal database since framework and database version # can differ this value must be an integer larger than 0 # Increase this value in case of backward incompatible changes # temporal database SQL layout tgis_db_version = 2 # We need to know the parameter style of the database backend tgis_dbmi_paramstyle = None
[docs]def get_tgis_dbmi_paramstyle(): """Return the temporal database backend parameter style :returns: "qmark" or "" """ global tgis_dbmi_paramstyle return tgis_dbmi_paramstyle # We need to access the current mapset quite often in the framework, so we make # a global variable that will be initiated when init() is called
current_mapset = None current_location = None current_gisdbase = None ###############################################################################
[docs]def get_current_mapset(): """Return the current mapset This is the fastest way to receive the current mapset. The current mapset is set by init() and stored in a global variable. This function provides access to this global variable. """ global current_mapset return current_mapset ###############################################################################
[docs]def get_current_location(): """Return the current location This is the fastest way to receive the current location. The current location is set by init() and stored in a global variable. This function provides access to this global variable. """ global current_location return current_location ###############################################################################
[docs]def get_current_gisdbase(): """Return the current gis database (gisdbase) This is the fastest way to receive the current gisdbase. The current gisdbase is set by init() and stored in a global variable. This function provides access to this global variable. """ global current_gisdbase return current_gisdbase ############################################################################### # If this global variable is set True, then maps can only be registered in # space time datasets with the same mapset. In addition, only maps in the # current mapset can be inserted, updated or deleted from the temporal database. # Overwrite this global variable by: g.gisenv set="TGIS_DISABLE_MAPSET_CHECK=True" # ATTENTION: Be aware to face corrupted temporal database in case this global # variable is set to False. This feature is highly # experimental and violates the grass permission guidance.
enable_mapset_check = True # If this global variable is set True, the timestamps of maps will be written # as textfiles for each map that will be inserted or updated in the temporal # database using the C-library timestamp interface. # Overwrite this global variable by: g.gisenv set="TGIS_DISABLE_TIMESTAMP_WRITE=True" # ATTENTION: Be aware to face corrupted temporal database in case this global # variable is set to False. This feature is highly # experimental and violates the grass permission guidance. enable_timestamp_write = True
[docs]def get_enable_mapset_check(): """Return True if the mapsets should be checked while insert, update, delete requests and space time dataset registration. If this global variable is set True, then maps can only be registered in space time datasets with the same mapset. In addition, only maps in the current mapset can be inserted, updated or deleted from the temporal database. Overwrite this global variable by: g.gisenv set="TGIS_DISABLE_MAPSET_CHECK=True" ..warning:: Be aware to face corrupted temporal database in case this global variable is set to False. This feature is highly experimental and violates the grass permission guidance. """ global enable_mapset_check return enable_mapset_check
[docs]def get_enable_timestamp_write(): """Return True if the map timestamps should be written to the spatial database metadata as well. If this global variable is set True, the timestamps of maps will be written as textfiles for each map that will be inserted or updated in the temporal database using the C-library timestamp interface. Overwrite this global variable by: g.gisenv set="TGIS_DISABLE_TIMESTAMP_WRITE=True" ..warning:: Be aware that C-libraries can not access timestamp information if they are not written as spatial database metadata, hence modules that make use of timestamps using the C-library interface will not work with maps that were created without writing the timestamps. """ global enable_timestamp_write return enable_timestamp_write ############################################################################### # The global variable that stores the PyGRASS Messenger object that # provides a fast and exit safe interface to the C-library message functions
message_interface = None def _init_tgis_message_interface(raise_on_error=False): """Initiate the global message interface :param raise_on_error: If True raise a FatalError exception in case of a fatal error, call sys.exit(1) otherwise """ global message_interface if message_interface is None: message_interface = messages.get_msgr(raise_on_error=raise_on_error)
[docs]def get_tgis_message_interface(): """Return the temporal GIS message interface which is of type grass.pygrass.message.Messenger() Use this message interface to print messages to stdout using the GRASS C-library messaging system. """ global message_interface return message_interface ############################################################################### # The global variable that stores the C-library interface object that # provides a fast and exit safe interface to the C-library libgis, # libraster, libraster3d and libvector functions
c_library_interface = None def _init_tgis_c_library_interface(): """Set the global C-library interface variable that provides a fast and exit safe interface to the C-library libgis, libraster, libraster3d and libvector functions """ global c_library_interface if c_library_interface is None: c_library_interface = CLibrariesInterface()
[docs]def get_tgis_c_library_interface(): """Return the C-library interface that provides a fast and exit safe interface to the C-library libgis, libraster, libraster3d and libvector functions """ global c_library_interface return c_library_interface ############################################################################### # Set this variable True to raise a FatalError exception # in case a fatal error occurs using the messenger interface
raise_on_error = False
[docs]def set_raise_on_error(raise_exp=True): """Define behavior on fatal error, invoked using the tgis messenger interface (msgr.fatal()) The messenger interface will be restarted using the new error policy :param raise_exp: True to raise a FatalError exception instead of calling sys.exit(1) when using the tgis messenger interface .. code-block:: python >>> import grass.temporal as tgis >>> tgis.init() >>> ignore = tgis.set_raise_on_error(False) >>> msgr = tgis.get_tgis_message_interface() >>> tgis.get_raise_on_error() False >>> msgr.fatal("Ohh no no no!") Traceback (most recent call last): File "__init__.py", line 239, in fatal sys.exit(1) SystemExit: 1 >>> tgis.set_raise_on_error(True) False >>> msgr.fatal("Ohh no no no!") Traceback (most recent call last): File "__init__.py", line 241, in fatal raise FatalError(message) FatalError: Ohh no no no! :returns: current status """ global raise_on_error tmp_raise = raise_on_error raise_on_error = raise_exp global message_interface if message_interface: message_interface.set_raise_on_error(raise_on_error) else: _init_tgis_message_interface(raise_on_error) return tmp_raise
[docs]def get_raise_on_error(): """Return True if a FatalError exception is raised instead of calling sys.exit(1) in case a fatal error was invoked with msgr.fatal() """ global raise_on_error return raise_on_error ###############################################################################
[docs]def get_tgis_version(): """Get the version number of the temporal framework :returns: The version number of the temporal framework as string """ global tgis_version return tgis_version ###############################################################################
[docs]def get_tgis_db_version(): """Get the version number of the temporal framework :returns: The version number of the temporal framework as string """ global tgis_db_version return tgis_db_version ###############################################################################
[docs]def get_tgis_metadata(dbif=None): """Return the tgis metadata table as a list of rows (dicts) or None if not present :param dbif: The database interface to be used :returns: The selected rows with key/value columns or None """ dbif, connected = init_dbif(dbif) # Select metadata if the table is present try: statement = "SELECT * FROM tgis_metadata;\n" dbif.execute(statement) rows = dbif.fetchall() except: rows = None if connected: dbif.close() return rows ############################################################################### # The temporal database string set with t.connect # with substituted GRASS variables gisdbase, location and mapset
tgis_database_string = None
[docs]def get_tgis_database_string(): """Return the preprocessed temporal database string This string is the temporal database string set with t.connect that was processed to substitue location, gisdbase and mapset variables. """ global tgis_database_string return tgis_database_string ###############################################################################
[docs]def get_sql_template_path(): base = os.getenv("GISBASE") base_etc = os.path.join(base, "etc") return os.path.join(base_etc, "sql") ###############################################################################
[docs]def stop_subprocesses(): """Stop the messenger and C-interface subprocesses that are started by tgis.init() """ global message_interface global c_library_interface if message_interface: message_interface.stop() if c_library_interface: c_library_interface.stop() # We register this function to be called at exit
atexit.register(stop_subprocesses)
[docs]def get_available_temporal_mapsets(): """Return a list of of mapset names with temporal database driver and names that are accessible from the current mapset. :returns: A dictionary, mapset names are keys, the tuple (driver, database) are the values """ global c_library_interface global message_interface mapsets = c_library_interface.available_mapsets() tgis_mapsets = {} for mapset in mapsets: driver = c_library_interface.get_driver_name(mapset) database = c_library_interface.get_database_name(mapset) message_interface.debug(1, "get_available_temporal_mapsets: "\ "\n mapset %s\n driver %s\n database %s"%(mapset, driver, database)) if driver and database: # Check if the temporal sqlite database exists # We need to set non-existing databases in case the mapset is the current mapset # to create it if (driver == "sqlite" and os.path.exists(database)) or mapset == get_current_mapset() : tgis_mapsets[mapset] = (driver, database) # We need to warn if the connection is defined but the database does not # exists if driver == "sqlite" and not os.path.exists(database): message_interface.warning("Temporal database connection defined as:\n" + \ database + "\nBut database file does not exist.") return tgis_mapsets ###############################################################################
[docs]def init(raise_fatal_error=False): """This function set the correct database backend from GRASS environmental variables and creates the grass temporal database structure for raster, vector and raster3d maps as well as for the space-time datasets strds, str3ds and stvds in case it does not exist. Several global variables are initiated and the messenger and C-library interface subprocesses are spawned. Re-run this function in case the following GRASS variables change while the process runs: - MAPSET - LOCATION_NAME - GISDBASE - TGIS_DISABLE_MAPSET_CHECK - TGIS_DISABLE_TIMESTAMP_WRITE Re-run this function if the following t.connect variables change while the process runs: - temporal GIS driver (set by t.connect driver=) - temporal GIS database (set by t.connect database=) The following environmental variables are checked: - GRASS_TGIS_PROFILE (True, False, 1, 0) - GRASS_TGIS_RAISE_ON_ERROR (True, False, 1, 0) ..warning:: This functions must be called before any spatio-temporal processing can be started :param raise_fatal_error: Set this True to assure that the init() function does not kill a persistent process like the GUI. If set True a grass.pygrass.messages.FatalError exception will be raised in case a fatal error occurs in the init process, otherwise sys.exit(1) will be called. """ # We need to set the correct database backend and several global variables # from the GRASS mapset specific environment variables of g.gisenv and t.connect global tgis_backend global tgis_database global tgis_database_string global tgis_dbmi_paramstyle global raise_on_error global enable_mapset_check global enable_timestamp_write global current_mapset global current_location global current_gisdbase raise_on_error = raise_fatal_error # We must run t.connect at first to create the temporal database and to # get the environmental variables gscript.run_command("t.connect", flags="c") grassenv = gscript.gisenv() # Set the global variable for faster access current_mapset = gscript.encode(grassenv["MAPSET"]) current_location = gscript.encode(grassenv["LOCATION_NAME"]) current_gisdbase = gscript.encode(grassenv["GISDBASE"]) # Check environment variable GRASS_TGIS_RAISE_ON_ERROR if os.getenv("GRASS_TGIS_RAISE_ON_ERROR") == "True" or \ os.getenv("GRASS_TGIS_RAISE_ON_ERROR") == "1": raise_on_error = True # Check if the script library raises on error, # if so we do the same if gscript.get_raise_on_error() is True: raise_on_error = True # Start the GRASS message interface server _init_tgis_message_interface(raise_on_error) # Start the C-library interface server _init_tgis_c_library_interface() msgr = get_tgis_message_interface() msgr.debug(1, "Initiate the temporal database") #"\n traceback:%s"%(str(" \n".join(traceback.format_stack())))) ciface = get_tgis_c_library_interface() driver_string = ciface.get_driver_name() database_string = ciface.get_database_name() # Set the mapset check and the timestamp write if "TGIS_DISABLE_MAPSET_CHECK" in grassenv: if gscript.encode(grassenv["TGIS_DISABLE_MAPSET_CHECK"]) == "True" or \ gscript.encode(grassenv["TGIS_DISABLE_MAPSET_CHECK"]) == "1": enable_mapset_check = False msgr.warning("TGIS_DISABLE_MAPSET_CHECK is True") if "TGIS_DISABLE_TIMESTAMP_WRITE" in grassenv: if gscript.encode(grassenv["TGIS_DISABLE_TIMESTAMP_WRITE"]) == "True" or \ gscript.encode(grassenv["TGIS_DISABLE_TIMESTAMP_WRITE"]) == "1": enable_timestamp_write = False msgr.warning("TGIS_DISABLE_TIMESTAMP_WRITE is True") if driver_string is not None and driver_string is not "": if driver_string == "sqlite": tgis_backend = driver_string try: import sqlite3 except ImportError: msgr.error("Unable to locate the sqlite SQL Python interface" " module sqlite3.") raise dbmi = sqlite3 elif driver_string == "pg": tgis_backend = driver_string try: import psycopg2 except ImportError: msgr.error("Unable to locate the Postgresql SQL Python " "interface module psycopg2.") raise dbmi = psycopg2 else: msgr.fatal(_("Unable to initialize the temporal DBMI interface. " "Please use t.connect to specify the driver and the" " database string")) else: # Set the default sqlite3 connection in case nothing was defined gscript.run_command("t.connect", flags="d") driver_string = ciface.get_driver_name() database_string = ciface.get_database_name() tgis_backend = driver_string try: import sqlite3 except ImportError: msgr.error("Unable to locate the sqlite SQL Python interface" " module sqlite3.") raise dbmi = sqlite3 tgis_database_string = database_string # Set the parameter style tgis_dbmi_paramstyle = dbmi.paramstyle # We do not know if the database already exists db_exists = False dbif = SQLDatabaseInterfaceConnection() # Check if the database already exists if tgis_backend == "sqlite": # Check path of the sqlite database if os.path.exists(tgis_database_string): dbif.connect() # Check for raster_base table dbif.execute("SELECT name FROM sqlite_master WHERE type='table' " "AND name='raster_base';") name = dbif.fetchone() if name and name[0] == "raster_base": db_exists = True dbif.close() elif tgis_backend == "pg": # Connect to database dbif.connect() # Check for raster_base table dbif.execute("SELECT EXISTS(SELECT * FROM information_schema.tables " "WHERE table_name=%s)", ('raster_base',)) if dbif.fetchone()[0]: db_exists = True backup_howto = "The format of your actual temporal database is not " \ "supported any more.\nSolution: You need to export it by " \ "restoring the GRASS GIS version used for creating this DB"\ ". From there, create a backup of your temporal database "\ "to avoid the loss of your temporal data.\nNotes: Use " \ "t.rast.export and t.vect.export to make a backup of your" \ " existing space time datasets.To safe the timestamps of" \ " your existing maps and space time datasets, use " \ "t.rast.list, t.vect.list and t.rast3d.list. "\ "You can register the existing time stamped maps easily if"\ " you export columns=id,start_time,end_time into text "\ "files and use t.register to register them again in new" \ " created space time datasets (t.create). After the backup"\ " remove the existing temporal database, a new one will be"\ " created automatically.\n" if db_exists is True: # Check the version of the temporal database dbif.close() dbif.connect() metadata = get_tgis_metadata(dbif) dbif.close() if metadata is None: msgr.fatal(_("Unable to receive temporal database metadata.\n" "Current temporal database info:%(info)s") % ( {"info": get_database_info_string()})) for entry in metadata: if "tgis_version" in entry and entry[1] != str(get_tgis_version()): msgr.fatal(_("Unsupported temporal database: version mismatch." "\n %(backup)s Supported temporal API version is:" " %(api)i.\nPlease update your GRASS GIS " "installation.\nCurrent temporal database info:" "%(info)s") % ({"backup": backup_howto, "api": get_tgis_version(), "info": get_database_info_string()})) if "tgis_db_version" in entry and entry[1] != str(get_tgis_db_version()): msgr.fatal(_("Unsupported temporal database: version mismatch." "\n %(backup)sSupported temporal database version" " is: %(tdb)i\nCurrent temporal database info:" "%(info)s") % ({"backup": backup_howto, "tdb": get_tgis_version(), "info": get_database_info_string()})) return create_temporal_database(dbif) ###############################################################################
[docs]def get_database_info_string(): dbif = SQLDatabaseInterfaceConnection() info = "\nDBMI interface:..... " + str(dbif.get_dbmi().__name__) info += "\nTemporal database:.. " + str(get_tgis_database_string()) return info ###############################################################################
[docs]def create_temporal_database(dbif): """This function will create the temporal database It will create all tables and triggers that are needed to run the temporal GIS :param dbif: The database interface to be used """ global tgis_backend global tgis_version global tgis_db_version global tgis_database_string template_path = get_sql_template_path() msgr = get_tgis_message_interface() # Read all SQL scripts and templates map_tables_template_sql = open(os.path.join( template_path, "map_tables_template.sql"), 'r').read() raster_metadata_sql = open(os.path.join( get_sql_template_path(), "raster_metadata_table.sql"), 'r').read() raster3d_metadata_sql = open(os.path.join(template_path, "raster3d_metadata_table.sql"), 'r').read() vector_metadata_sql = open(os.path.join(template_path, "vector_metadata_table.sql"), 'r').read() raster_views_sql = open(os.path.join(template_path, "raster_views.sql"), 'r').read() raster3d_views_sql = open(os.path.join(template_path, "raster3d_views.sql"), 'r').read() vector_views_sql = open(os.path.join(template_path, "vector_views.sql"), 'r').read() stds_tables_template_sql = open(os.path.join(template_path, "stds_tables_template.sql"), 'r').read() strds_metadata_sql = open(os.path.join(template_path, "strds_metadata_table.sql"), 'r').read() str3ds_metadata_sql = open(os.path.join(template_path, "str3ds_metadata_table.sql"), 'r').read() stvds_metadata_sql = open(os.path.join(template_path, "stvds_metadata_table.sql"), 'r').read() strds_views_sql = open(os.path.join(template_path, "strds_views.sql"), 'r').read() str3ds_views_sql = open(os.path.join(template_path, "str3ds_views.sql"), 'r').read() stvds_views_sql = open(os.path.join(template_path, "stvds_views.sql"), 'r').read() # Create the raster, raster3d and vector tables SQL statements raster_tables_sql = map_tables_template_sql.replace("GRASS_MAP", "raster") vector_tables_sql = map_tables_template_sql.replace("GRASS_MAP", "vector") raster3d_tables_sql = map_tables_template_sql.replace( "GRASS_MAP", "raster3d") # Create the space-time raster, raster3d and vector dataset tables # SQL statements strds_tables_sql = stds_tables_template_sql.replace("STDS", "strds") stvds_tables_sql = stds_tables_template_sql.replace("STDS", "stvds") str3ds_tables_sql = stds_tables_template_sql.replace("STDS", "str3ds") msgr.message(_("Creating temporal database: %s" % (str(tgis_database_string)))) if tgis_backend == "sqlite": # We need to create the sqlite3 database path if it does not exist tgis_dir = os.path.dirname(tgis_database_string) if not os.path.exists(tgis_dir): try: os.makedirs(tgis_dir) except Exception as e: msgr.fatal(_("Unable to create SQLite temporal database\n" "Exception: %s\nPlease use t.connect to set a " "read- and writable temporal database path" % (e))) # Set up the trigger that takes care of # the correct deletion of entries across the different tables delete_trigger_sql = open(os.path.join(template_path, "sqlite3_delete_trigger.sql"), 'r').read() indexes_sql = open(os.path.join(template_path, "sqlite3_indexes.sql"), 'r').read() else: # Set up the trigger that takes care of # the correct deletion of entries across the different tables delete_trigger_sql = open(os.path.join(template_path, "postgresql_delete_trigger.sql"), 'r').read() indexes_sql = open(os.path.join(template_path, "postgresql_indexes.sql"), 'r').read() # Connect now to the database if dbif.connected is not True: dbif.connect() # Execute the SQL statements for sqlite # Create the global tables for the native grass datatypes dbif.execute_transaction(raster_tables_sql) dbif.execute_transaction(raster_metadata_sql) dbif.execute_transaction(raster_views_sql) dbif.execute_transaction(vector_tables_sql) dbif.execute_transaction(vector_metadata_sql) dbif.execute_transaction(vector_views_sql) dbif.execute_transaction(raster3d_tables_sql) dbif.execute_transaction(raster3d_metadata_sql) dbif.execute_transaction(raster3d_views_sql) # Create the tables for the new space-time datatypes dbif.execute_transaction(strds_tables_sql) dbif.execute_transaction(strds_metadata_sql) dbif.execute_transaction(strds_views_sql) dbif.execute_transaction(stvds_tables_sql) dbif.execute_transaction(stvds_metadata_sql) dbif.execute_transaction(stvds_views_sql) dbif.execute_transaction(str3ds_tables_sql) dbif.execute_transaction(str3ds_metadata_sql) dbif.execute_transaction(str3ds_views_sql) # The delete trigger dbif.execute_transaction(delete_trigger_sql) # The indexes dbif.execute_transaction(indexes_sql) # Create the tgis metadata table to store the database # initial configuration # The metadata table content metadata = {} metadata["tgis_version"] = tgis_version metadata["tgis_db_version"] = tgis_db_version metadata["creation_time"] = datetime.today() _create_tgis_metadata_table(metadata, dbif) dbif.close() ###############################################################################
def _create_tgis_metadata_table(content, dbif=None): """!Create the temporal gis metadata table which stores all metadata information about the temporal database. :param content: The dictionary that stores the key:value metadata that should be stored in the metadata table :param dbif: The database interface to be used """ dbif, connected = init_dbif(dbif) statement = "CREATE TABLE tgis_metadata (key VARCHAR NOT NULL, value VARCHAR);\n"; dbif.execute_transaction(statement) for key in content.keys(): statement = "INSERT INTO tgis_metadata (key, value) VALUES " + \ "(\'%s\' , \'%s\');\n" % (str(key), str(content[key])) dbif.execute_transaction(statement) if connected: dbif.close() ###############################################################################
[docs]class SQLDatabaseInterfaceConnection(object): def __init__(self): self.tgis_mapsets = get_available_temporal_mapsets() self.current_mapset = get_current_mapset() self.connections = {} self.connected = False self.unique_connections = {} for mapset in self.tgis_mapsets.keys(): driver, dbstring = self.tgis_mapsets[mapset] if dbstring not in self.unique_connections.keys(): self.unique_connections[dbstring] = DBConnection(backend=driver, dbstring=dbstring) self.connections[mapset] = self.unique_connections[dbstring] self.msgr = get_tgis_message_interface()
[docs] def get_dbmi(self, mapset=None): if mapset is None: mapset = self.current_mapset return self.connections[mapset].dbmi
[docs] def rollback(self, mapset=None): """ Roll back the last transaction. This must be called in case a new query should be performed after a db error. This is only relevant for postgresql database. """ if mapset is None: mapset = self.current_mapset
[docs] def connect(self): """Connect to the DBMI to execute SQL statements Supported backends are sqlite3 and postgresql """ for mapset in self.tgis_mapsets.keys(): driver, dbstring = self.tgis_mapsets[mapset] conn = self.connections[mapset] if conn.is_connected() is False: conn.connect(dbstring) self.connected = True
[docs] def is_connected(self): return self.connected
[docs] def close(self): """Close the DBMI connection There may be several temporal databases in a location, hence close all temporal databases that have been opened. """ for key in self.unique_connections.keys(): self.unique_connections[key].close() self.connected = False
[docs] def mogrify_sql_statement(self, content, mapset=None): """Return the SQL statement and arguments as executable SQL string :param content: The content as tuple with two entries, the first entry is the SQL statement with DBMI specific place holder (?), the second entry is the argument list that should substitute the place holder. :param mapset: The mapset of the abstract dataset or temporal database location, if None the current mapset will be used """ if mapset is None: mapset = self.current_mapset if mapset not in self.tgis_mapsets.keys(): self.msgr.fatal(_("Unable to mogrify sql statement. " + self._create_mapset_error_message(mapset))) return self.connections[mapset].mogrify_sql_statement(content)
[docs] def check_table(self, table_name, mapset=None): """Check if a table exists in the temporal database :param table_name: The name of the table to be checked for existence :param mapset: The mapset of the abstract dataset or temporal database location, if None the current mapset will be used :returns: True if the table exists, False otherwise TODO: There may be several temporal databases in a location, hence the mapset is used to query the correct temporal database. """ if mapset is None: mapset = self.current_mapset if mapset not in self.tgis_mapsets.keys(): self.msgr.fatal(_("Unable to check table. " + self._create_mapset_error_message(mapset))) return self.connections[mapset].check_table(table_name)
[docs] def execute(self, statement, args=None, mapset=None): """ :param mapset: The mapset of the abstract dataset or temporal database location, if None the current mapset will be used """ if mapset is None: mapset = self.current_mapset if mapset not in self.tgis_mapsets.keys(): self.msgr.fatal(_("Unable to execute sql statement. " + self._create_mapset_error_message(mapset))) return self.connections[mapset].execute(statement, args)
[docs] def fetchone(self, mapset=None): if mapset is None: mapset = self.current_mapset if mapset not in self.tgis_mapsets.keys(): self.msgr.fatal(_("Unable to fetch one. " + self._create_mapset_error_message(mapset))) return self.connections[mapset].fetchone()
[docs] def fetchall(self, mapset=None): if mapset is None: mapset = self.current_mapset if mapset not in self.tgis_mapsets.keys(): self.msgr.fatal(_("Unable to fetch all. " + self._create_mapset_error_message(mapset))) return self.connections[mapset].fetchall()
[docs] def execute_transaction(self, statement, mapset=None): """Execute a transactional SQL statement The BEGIN and END TRANSACTION statements will be added automatically to the sql statement :param statement: The executable SQL statement or SQL script """ if mapset is None: mapset = self.current_mapset if mapset not in self.tgis_mapsets.keys(): self.msgr.fatal(_("Unable to execute transaction. " + self._create_mapset_error_message(mapset))) return self.connections[mapset].execute_transaction(statement)
def _create_mapset_error_message(self, mapset): return("You have no permission to " "access mapset <%(mapset)s>, or " "mapset <%(mapset)s> has no temporal database. " "Accessible mapsets are: <%(mapsets)s>" % \ {"mapset": mapset, "mapsets":','.join(self.tgis_mapsets.keys())}) ###############################################################################
[docs]class DBConnection(object): """This class represents the database interface connection and provides access to the chosen backend modules. The following DBMS are supported: - sqlite via the sqlite3 standard library - postgresql via psycopg2 """ def __init__(self, backend=None, dbstring=None): """ Constructor of a database connection param backend:The database backend sqlite or pg param dbstring: The database connection string """ self.connected = False if backend is None: global tgis_backend if tgis_backend == "sqlite": self.dbmi = sqlite3 else: self.dbmi = psycopg2 else: if backend == "sqlite": self.dbmi = sqlite3 else: self.dbmi = psycopg2 if dbstring is None: global tgis_database_string self.dbstring = tgis_database_string self.dbstring = dbstring self.msgr = get_tgis_message_interface() self.msgr.debug(1, "DBConnection constructor:"\ "\n backend: %s"\ "\n dbstring: %s"%(backend, self.dbstring)) #"\n traceback:%s"%(backend, self.dbstring, #str(" \n".join(traceback.format_stack())))) def __del__(self): if self.connected is True: self.close()
[docs] def is_connected(self): return self.connected
[docs] def rollback(self): """ Roll back the last transaction. This must be called in case a new query should be performed after a db error. This is only relevant for postgresql database. """ if self.dbmi.__name__ == "psycopg2": if self.connected: self.connection.rollback()
[docs] def connect(self, dbstring=None): """Connect to the DBMI to execute SQL statements Supported backends are sqlite3 and postgresql param dbstring: The database connection string """ # Connection in the current mapset if dbstring is None: dbstring = self.dbstring try: if self.dbmi.__name__ == "sqlite3": self.connection = self.dbmi.connect(dbstring, detect_types=self.dbmi.PARSE_DECLTYPES | self.dbmi.PARSE_COLNAMES) self.connection.row_factory = self.dbmi.Row self.connection.isolation_level = None self.connection.text_factory = str self.cursor = self.connection.cursor() self.cursor.execute("PRAGMA synchronous = OFF") self.cursor.execute("PRAGMA journal_mode = MEMORY") elif self.dbmi.__name__ == "psycopg2": self.connection = self.dbmi.connect(dbstring) #self.connection.set_isolation_level(dbmi.extensions.ISOLATION_LEVEL_AUTOCOMMIT) self.cursor = self.connection.cursor( cursor_factory=self.dbmi.extras.DictCursor) self.connected = True except Exception as e: self.msgr.fatal(_("Unable to connect to %(db)s database: " "%(string)s\nException: \"%(ex)s\"\nPlease use" " t.connect to set a read- and writable " "temporal database backend") % ( {"db": self.dbmi.__name__, "string": tgis_database_string, "ex": e, }))
[docs] def close(self): """Close the DBMI connection TODO: There may be several temporal databases in a location, hence close all temporal databases that have been opened. Use a dictionary to manage different connections. """ self.connection.commit() self.cursor.close() self.connected = False
[docs] def mogrify_sql_statement(self, content): """Return the SQL statement and arguments as executable SQL string TODO: Use the mapset argument to identify the correct database driver :param content: The content as tuple with two entries, the first entry is the SQL statement with DBMI specific place holder (?), the second entry is the argument list that should substitute the place holder. :param mapset: The mapset of the abstract dataset or temporal database location, if None the current mapset will be used Usage: .. code-block:: python >>> init() >>> dbif = SQLDatabaseInterfaceConnection() >>> dbif.mogrify_sql_statement(["SELECT ctime FROM raster_base WHERE id = ?", ... ["soil@PERMANENT",]]) "SELECT ctime FROM raster_base WHERE id = 'soil@PERMANENT'" """ sql = content[0] args = content[1] if self.dbmi.__name__ == "psycopg2": if len(args) == 0: return sql else: if self.connected: try: return self.cursor.mogrify(sql, args) except Exception as exc: print(sql, args) raise exc else: self.connect() statement = self.cursor.mogrify(sql, args) self.close() return statement elif self.dbmi.__name__ == "sqlite3": if len(args) == 0: return sql else: # Unfortunately as sqlite does not support # the transformation of sql strings and qmarked or # named arguments we must make our hands dirty # and do it by ourself. :( # Doors are open for SQL injection because of the # limited python sqlite3 implementation!!! pos = 0 count = 0 maxcount = 100 statement = sql while count < maxcount: pos = statement.find("?", pos + 1) if pos == -1: break if args[count] is None: statement = "%sNULL%s" % (statement[0:pos], statement[pos + 1:]) elif isinstance(args[count], (int, long)): statement = "%s%d%s" % (statement[0:pos], args[count], statement[pos + 1:]) elif isinstance(args[count], float): statement = "%s%f%s" % (statement[0:pos], args[count], statement[pos + 1:]) elif isinstance(args[count], datetime): statement = "%s\'%s\'%s" % (statement[0:pos], str(args[count]), statement[pos + 1:]) else: # Default is a string, this works for datetime # objects too statement = "%s\'%s\'%s" % (statement[0:pos], str(args[count]), str(statement[pos + 1:])) count += 1 return statement
[docs] def check_table(self, table_name): """Check if a table exists in the temporal database :param table_name: The name of the table to be checked for existence :param mapset: The mapset of the abstract dataset or temporal database location, if None the current mapset will be used :returns: True if the table exists, False otherwise TODO: There may be several temporal databases in a location, hence the mapset is used to query the correct temporal database. """ table_exists = False connected = False if not self.connected: self.connect() connected = True # Check if the database already exists if self.dbmi.__name__ == "sqlite3": self.cursor.execute("SELECT name FROM sqlite_master WHERE " "type='table' AND name='%s';" % table_name) name = self.cursor.fetchone() if name and name[0] == table_name: table_exists = True else: # Check for raster_base table self.cursor.execute("SELECT EXISTS(SELECT * FROM information_schema.tables " "WHERE table_name=%s)", ('%s' % table_name,)) if self.cursor.fetchone()[0]: table_exists = True if connected: self.close() return table_exists
[docs] def execute(self, statement, args=None): """Execute a SQL statement :param statement: The executable SQL statement or SQL script """ connected = False if not self.connected: self.connect() connected = True try: if args: self.cursor.execute(statement, args) else: self.cursor.execute(statement) except: if connected: self.close() self.msgr.error(_("Unable to execute :\n %(sql)s" % {"sql": statement})) raise if connected: self.close()
[docs] def fetchone(self): if self.connected: return self.cursor.fetchone() return None
[docs] def fetchall(self): if self.connected: return self.cursor.fetchall() return None
[docs] def execute_transaction(self, statement, mapset=None): """Execute a transactional SQL statement The BEGIN and END TRANSACTION statements will be added automatically to the sql statement :param statement: The executable SQL statement or SQL script """ connected = False if not self.connected: self.connect() connected = True sql_script = "" sql_script += "BEGIN TRANSACTION;\n" sql_script += statement sql_script += "END TRANSACTION;" try: if self.dbmi.__name__ == "sqlite3": self.cursor.executescript(statement) else: self.cursor.execute(statement) self.connection.commit() except: if connected: self.close() self.msgr.error(_("Unable to execute transaction:\n %(sql)s" % {"sql": statement})) raise if connected: self.close() ###############################################################################
[docs]def init_dbif(dbif): """This method checks if the database interface connection exists, if not a new one will be created, connected and True will be returned. If the database interface exists but is connected, the connection will be established. :returns: the tuple (dbif, True|False) Usage code sample: .. code-block:: python dbif, connect = tgis.init_dbif(None) sql = dbif.mogrify_sql_statement(["SELECT * FROM raster_base WHERE ? = ?"], ["id", "soil@PERMANENT"]) dbif.execute_transaction(sql) if connect: dbif.close() """ if dbif is None: dbif = SQLDatabaseInterfaceConnection() dbif.connect() return dbif, True elif dbif.is_connected() is False: dbif.connect() return dbif, True return dbif, False ###############################################################################
if __name__ == "__main__": import doctest doctest.testmod()

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