exceptions.py

SQLAlchemy. 经典的Python ORM框架。学习必看。

# exceptions.py - exceptions for SQLAlchemy
# Copyright (C) 2005, 2006, 2007, 2008 Michael Bayer [e-mail]
#
# This module is part of SQLAlchemy and is released under
# the MIT License: http://www.opensource.org/licenses/mit-license.php
"""Exceptions used with SQLAlchemy.

The base exception class is SQLAlchemyError.  Exceptions which are raised as a result
of DBAPI exceptions are all subclasses of [sqlalchemy.exceptions#DBAPIError]."""

class SQLAlchemyError(Exception):
    """Generic error class."""


class ArgumentError(SQLAlchemyError):
    """Raised for all those conditions where invalid arguments are
    sent to constructed objects.  This error generally corresponds to
    construction time state errors.
    """


class CompileError(SQLAlchemyError):
    """Raised when an error occurs during SQL compilation"""


class TimeoutError(SQLAlchemyError):
    """Raised when a connection pool times out on getting a connection."""


class ConcurrentModificationError(SQLAlchemyError):
    """Raised when a concurrent modification condition is detected."""


class CircularDependencyError(SQLAlchemyError):
    """Raised by topological sorts when a circular dependency is detected"""


class FlushError(SQLAlchemyError):
    """Raised when an invalid condition is detected upon a ``flush()``."""


class InvalidRequestError(SQLAlchemyError):
    """SQLAlchemy was asked to do something it can't do, return
    nonexistent data, etc.

    This error generally corresponds to runtime state errors.
    """

class UnmappedColumnError(InvalidRequestError):
    """A mapper was asked to return mapped information about a column
    which it does not map"""

class NoSuchTableError(InvalidRequestError):
    """SQLAlchemy was asked to load a table's definition from the
    database, but the table doesn't exist.
    """

class UnboundExecutionError(InvalidRequestError):
    """SQL was attempted without a database connection to execute it on."""

class AssertionError(SQLAlchemyError):
    """Corresponds to internal state being detected in an invalid state."""


class NoSuchColumnError(KeyError, SQLAlchemyError):
    """Raised by ``RowProxy`` when a nonexistent column is requested from a row."""


class DisconnectionError(SQLAlchemyError):
    """Raised within ``Pool`` when a disconnect is detected on a raw DB-API connection.

    This error is consumed internally by a connection pool.  It can be raised by
    a ``PoolListener`` so that the host pool forces a disconnect.
    """


class DBAPIError(SQLAlchemyError):
    """Raised when the execution of a database operation fails.

    ``DBAPIError`` wraps exceptions raised by the DB-API underlying the
    database operation.  Driver-specific implementations of the standard
    DB-API exception types are wrapped by matching sub-types of SQLAlchemy's
    ``DBAPIError`` when possible.  DB-API's ``Error`` type maps to
    ``DBAPIError`` in SQLAlchemy, otherwise the names are identical.  Note
    that there is no guarantee that different DB-API implementations will
    raise the same exception type for any given error condition.

    If the error-raising operation occured in the execution of a SQL
    statement, that statement and its parameters will be available on
    the exception object in the ``statement`` and ``params`` attributes.

    The wrapped exception object is available in the ``orig`` attribute.
    Its type and properties are DB-API implementation specific.
    """

    def instance(cls, statement, params, orig, connection_invalidated=False):
        # Don't ever wrap these, just return them directly as if
        # DBAPIError didn't exist.
        if isinstance(orig, (KeyboardInterrupt, SystemExit)):
            return orig

        if orig is not None:
            name, glob = orig.__class__.__name__, globals()
            if name in glob and issubclass(glob[name], DBAPIError):
                cls = glob[name]

        return cls(statement, params, orig, connection_invalidated)
    instance = classmethod(instance)

    def __init__(self, statement, params, orig, connection_invalidated=False):
        try:
            text = str(orig)
        except (KeyboardInterrupt, SystemExit):
            raise
        except Exception, e:
            text = 'Error in str() of DB-API-generated exception: ' + str(e)
        SQLAlchemyError.__init__(
            self, "(%s) %s" % (orig.__class__.__name__, text))
        self.statement = statement
        self.params = params
        self.orig = orig
        self.connection_invalidated = connection_invalidated

    def __str__(self):
        return ' '.join([SQLAlchemyError.__str__(self),
                         repr(self.statement), repr(self.params)])


# As of 0.4, SQLError is now DBAPIError
SQLError = DBAPIError

class InterfaceError(DBAPIError):
    """Wraps a DB-API InterfaceError."""

class DatabaseError(DBAPIError):
    """Wraps a DB-API DatabaseError."""

class DataError(DatabaseError):
    """Wraps a DB-API DataError."""

class OperationalError(DatabaseError):
    """Wraps a DB-API OperationalError."""

class IntegrityError(DatabaseError):
    """Wraps a DB-API IntegrityError."""

class InternalError(DatabaseError):
    """Wraps a DB-API InternalError."""

class ProgrammingError(DatabaseError):
    """Wraps a DB-API ProgrammingError."""

class NotSupportedError(DatabaseError):
    """Wraps a DB-API NotSupportedError."""

# Warnings
class SADeprecationWarning(DeprecationWarning):
    """Issued once per usage of a deprecated API."""

class SAWarning(RuntimeWarning):
    """Issued at runtime."""