386 lines
12 KiB
Python
386 lines
12 KiB
Python
# vim: ft=python fileencoding=utf-8 sts=4 sw=4 et:
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# Copyright 2016-2018 Ryan Roden-Corrent (rcorre) <ryan@rcorre.net>
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#
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# This file is part of qutebrowser.
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#
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# qutebrowser is free software: you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation, either version 3 of the License, or
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# (at your option) any later version.
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#
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# qutebrowser is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with qutebrowser. If not, see <http://www.gnu.org/licenses/>.
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"""Provides access to an in-memory sqlite database."""
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import collections
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from PyQt5.QtCore import QObject, pyqtSignal
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from PyQt5.QtSql import QSqlDatabase, QSqlQuery, QSqlError
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from qutebrowser.utils import log, debug
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class SqliteErrorCode:
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"""Error codes as used by sqlite.
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See https://sqlite.org/rescode.html - note we only define the codes we use
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in qutebrowser here.
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"""
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UNKNOWN = '-1'
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BUSY = '5' # database is locked
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READONLY = '8' # attempt to write a readonly database
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IOERR = '10' # disk I/O error
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CORRUPT = '11' # database disk image is malformed
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FULL = '13' # database or disk is full
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CANTOPEN = '14' # unable to open database file
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CONSTRAINT = '19' # UNIQUE constraint failed
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class SqlError(Exception):
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"""Base class for all SQL related errors."""
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def __init__(self, msg, error=None):
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super().__init__(msg)
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self.error = error
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def text(self):
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"""Get a short text description of the error.
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This is a string suitable to show to the user as error message.
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"""
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if self.error is None:
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return str(self)
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else:
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return self.error.databaseText()
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class SqlEnvironmentError(SqlError):
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"""Raised on an error interacting with the SQL database.
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This is raised in conditions resulting from the environment (like a full
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disk or I/O errors), where qutebrowser isn't to blame.
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"""
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pass
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class SqlBugError(SqlError):
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"""Raised on an error interacting with the SQL database.
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This is raised for errors resulting from a qutebrowser bug.
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"""
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pass
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def raise_sqlite_error(msg, error):
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"""Raise either a SqlBugError or SqlEnvironmentError."""
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error_code = error.nativeErrorCode()
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database_text = error.databaseText()
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driver_text = error.driverText()
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log.sql.debug("SQL error:")
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log.sql.debug("type: {}".format(
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debug.qenum_key(QSqlError, error.type())))
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log.sql.debug("database text: {}".format(database_text))
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log.sql.debug("driver text: {}".format(driver_text))
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log.sql.debug("error code: {}".format(error_code))
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environmental_errors = [
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SqliteErrorCode.BUSY,
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SqliteErrorCode.READONLY,
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SqliteErrorCode.IOERR,
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SqliteErrorCode.CORRUPT,
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SqliteErrorCode.FULL,
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SqliteErrorCode.CANTOPEN,
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]
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# WORKAROUND for https://bugreports.qt.io/browse/QTBUG-70506
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# We don't know what the actual error was, but let's assume it's not us to
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# blame... Usually this is something like an unreadable database file.
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qtbug_70506 = (error_code == SqliteErrorCode.UNKNOWN and
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driver_text == "Error opening database" and
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database_text == "out of memory")
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if error_code in environmental_errors or qtbug_70506:
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raise SqlEnvironmentError(msg, error)
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else:
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raise SqlBugError(msg, error)
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def init(db_path):
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"""Initialize the SQL database connection."""
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database = QSqlDatabase.addDatabase('QSQLITE')
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if not database.isValid():
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raise SqlEnvironmentError('Failed to add database. Are sqlite and Qt '
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'sqlite support installed?')
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database.setDatabaseName(db_path)
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if not database.open():
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error = database.lastError()
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msg = "Failed to open sqlite database at {}: {}".format(db_path,
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error.text())
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raise_sqlite_error(msg, error)
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# Enable write-ahead-logging and reduce disk write frequency
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# see https://sqlite.org/pragma.html and issues #2930 and #3507
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Query("PRAGMA journal_mode=WAL").run()
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Query("PRAGMA synchronous=NORMAL").run()
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def close():
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"""Close the SQL connection."""
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QSqlDatabase.removeDatabase(QSqlDatabase.database().connectionName())
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def version():
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"""Return the sqlite version string."""
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try:
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if not QSqlDatabase.database().isOpen():
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init(':memory:')
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ver = Query("select sqlite_version()").run().value()
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close()
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return ver
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return Query("select sqlite_version()").run().value()
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except SqlEnvironmentError as e:
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return 'UNAVAILABLE ({})'.format(e)
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class Query:
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"""A prepared SQL Query."""
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def __init__(self, querystr, forward_only=True):
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"""Prepare a new sql query.
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Args:
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querystr: String to prepare query from.
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forward_only: Optimization for queries that will only step forward.
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Must be false for completion queries.
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"""
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self.query = QSqlQuery(QSqlDatabase.database())
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log.sql.debug('Preparing SQL query: "{}"'.format(querystr))
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ok = self.query.prepare(querystr)
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self._check_ok('prepare', ok)
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self.query.setForwardOnly(forward_only)
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def __iter__(self):
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if not self.query.isActive():
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raise SqlBugError("Cannot iterate inactive query")
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rec = self.query.record()
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fields = [rec.fieldName(i) for i in range(rec.count())]
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rowtype = collections.namedtuple('ResultRow', fields)
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while self.query.next():
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rec = self.query.record()
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yield rowtype(*[rec.value(i) for i in range(rec.count())])
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def _check_ok(self, step, ok):
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if not ok:
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query = self.query.lastQuery()
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error = self.query.lastError()
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msg = 'Failed to {} query "{}": "{}"'.format(step, query,
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error.text())
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raise_sqlite_error(msg, error)
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def _bind_values(self, values):
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for key, val in values.items():
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self.query.bindValue(':{}'.format(key), val)
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if any(val is None for val in self.bound_values().values()):
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raise SqlBugError("Missing bound values!")
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def run(self, **values):
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"""Execute the prepared query."""
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log.sql.debug('Running SQL query: "{}"'.format(
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self.query.lastQuery()))
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self._bind_values(values)
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log.sql.debug('query bindings: {}'.format(self.bound_values()))
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ok = self.query.exec_()
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self._check_ok('exec', ok)
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return self
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def run_batch(self, values):
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"""Execute the query in batch mode."""
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log.sql.debug('Running SQL query (batch): "{}"'.format(
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self.query.lastQuery()))
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self._bind_values(values)
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db = QSqlDatabase.database()
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ok = db.transaction()
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self._check_ok('transaction', ok)
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ok = self.query.execBatch()
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try:
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self._check_ok('execBatch', ok)
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except SqlError:
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# Not checking the return value here, as we're failing anyways...
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db.rollback()
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raise
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ok = db.commit()
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self._check_ok('commit', ok)
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def value(self):
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"""Return the result of a single-value query (e.g. an EXISTS)."""
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if not self.query.next():
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raise SqlBugError("No result for single-result query")
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return self.query.record().value(0)
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def rows_affected(self):
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return self.query.numRowsAffected()
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def bound_values(self):
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return self.query.boundValues()
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class SqlTable(QObject):
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"""Interface to a sql table.
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Attributes:
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_name: Name of the SQL table this wraps.
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Signals:
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changed: Emitted when the table is modified.
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"""
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changed = pyqtSignal()
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def __init__(self, name, fields, constraints=None, parent=None):
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"""Create a new table in the sql database.
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Does nothing if the table already exists.
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Args:
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name: Name of the table.
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fields: A list of field names.
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constraints: A dict mapping field names to constraint strings.
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"""
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super().__init__(parent)
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self._name = name
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constraints = constraints or {}
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column_defs = ['{} {}'.format(field, constraints.get(field, ''))
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for field in fields]
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q = Query("CREATE TABLE IF NOT EXISTS {name} ({column_defs})"
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.format(name=name, column_defs=', '.join(column_defs)))
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q.run()
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def create_index(self, name, field):
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"""Create an index over this table.
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Args:
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name: Name of the index, should be unique.
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field: Name of the field to index.
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"""
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q = Query("CREATE INDEX IF NOT EXISTS {name} ON {table} ({field})"
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.format(name=name, table=self._name, field=field))
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q.run()
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def __iter__(self):
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"""Iterate rows in the table."""
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q = Query("SELECT * FROM {table}".format(table=self._name))
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q.run()
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return iter(q)
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def contains_query(self, field):
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"""Return a prepared query that checks for the existence of an item.
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Args:
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field: Field to match.
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"""
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return Query(
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"SELECT EXISTS(SELECT * FROM {table} WHERE {field} = :val)"
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.format(table=self._name, field=field))
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def __len__(self):
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"""Return the count of rows in the table."""
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q = Query("SELECT count(*) FROM {table}".format(table=self._name))
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q.run()
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return q.value()
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def delete(self, field, value):
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"""Remove all rows for which `field` equals `value`.
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Args:
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field: Field to use as the key.
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value: Key value to delete.
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Return:
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The number of rows deleted.
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"""
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q = Query("DELETE FROM {table} where {field} = :val"
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.format(table=self._name, field=field))
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q.run(val=value)
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if not q.rows_affected():
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raise KeyError('No row with {} = "{}"'.format(field, value))
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self.changed.emit()
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def _insert_query(self, values, replace):
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params = ', '.join(':{}'.format(key) for key in values)
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verb = "REPLACE" if replace else "INSERT"
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return Query("{verb} INTO {table} ({columns}) values({params})".format(
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verb=verb, table=self._name, columns=', '.join(values),
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params=params))
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def insert(self, values, replace=False):
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"""Append a row to the table.
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Args:
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values: A dict with a value to insert for each field name.
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replace: If set, replace existing values.
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"""
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q = self._insert_query(values, replace)
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q.run(**values)
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self.changed.emit()
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def insert_batch(self, values, replace=False):
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"""Performantly append multiple rows to the table.
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Args:
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values: A dict with a list of values to insert for each field name.
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replace: If true, overwrite rows with a primary key match.
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"""
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q = self._insert_query(values, replace)
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q.run_batch(values)
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self.changed.emit()
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def delete_all(self):
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"""Remove all rows from the table."""
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Query("DELETE FROM {table}".format(table=self._name)).run()
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self.changed.emit()
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def select(self, sort_by, sort_order, limit=-1):
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"""Prepare, run, and return a select statement on this table.
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Args:
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sort_by: name of column to sort by.
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sort_order: 'asc' or 'desc'.
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limit: max number of rows in result, defaults to -1 (unlimited).
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Return: A prepared and executed select query.
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"""
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q = Query("SELECT * FROM {table} ORDER BY {sort_by} {sort_order} "
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"LIMIT :limit"
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.format(table=self._name, sort_by=sort_by,
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sort_order=sort_order))
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q.run(limit=limit)
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return q
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