sqlalchemy.exc OperationalError Example Code

OperationalError is a class within the sqlalchemy.exc module of the SQLAlchemy project.

ArgumentError, DataError, DatabaseError, IntegrityError, InvalidRequestError, NoInspectionAvailable, NoSuchTableError, ProgrammingError, and UnsupportedCompilationError are several other callables with code examples from the same sqlalchemy.exc package.

Example 1 from indico

indico (project website, documentation and sandbox demo) is a Flask-based web app for event management that is powered by SQLAlchemy on the backend. The code for this project is open sourced under the MIT license.

indico / indico / web / errors.py

# errors.py

from __future__ import absolute_import, unicode_literals

import traceback
from uuid import uuid4

from flask import g, jsonify, render_template, request, session
from itsdangerous import BadData
from sqlalchemy.exc import OperationalError
from werkzeug.exceptions import Forbidden, HTTPException

from indico.core.errors import NoReportError
from indico.legacy.common.cache import GenericCache
from indico.web.util import get_request_info
from indico.web.views import WPError


def render_error(exc, title, message, code, standalone=False):
    _save_error(exc, title, message)
    if _need_json_response():
        return _jsonify_error(exc, title, message, code)
    elif standalone:
        return render_template('standalone_error.html', error_message=title, error_description=message), code
    else:
        try:
            return WPError(title, message).getHTML(), code
        except OperationalError:
            return render_error(exc, title, message, code, standalone=True)


def load_error_data(uuid):
    return GenericCache('errors').get(uuid)


def _save_error(exc, title, message):
    if 'saved_error_uuid' in g:
        return
    if not _is_error_reportable(exc):
        return
    g.saved_error_uuid = uuid = unicode(uuid4())
    tb = traceback.format_exc()
    data = {'title': title,
            'message': message,
            'request_info': get_request_info(),
            'traceback': tb,
            'sentry_event_id': g.get('sentry_event_id')}
    GenericCache('errors').set(uuid, data, 7200)


def _need_json_response():
    return request.is_xhr or request.is_json


## ... source file continues with no further OperationalError examples...

Example 2 from sqlalchemy-utils

sqlalchemy-utils (project documentation and PyPI package information) is a code library with various helper functions and new data types that make it easier to use SQLAlchemy when building projects that involve more specific storage requirements such as currency. The wide array of data types includes ranged values and aggregated attributes.

sqlalchemy-utils / sqlalchemy_utils / functions / database.py

# database.py
import itertools
import os
from collections.abc import Mapping, Sequence
from copy import copy

import sqlalchemy as sa
from sqlalchemy.engine.url import make_url
from sqlalchemy.exc import OperationalError, ProgrammingError

from ..utils import starts_with
from .orm import quote


def escape_like(string, escape_char='*'):
    return (
        string
        .replace(escape_char, escape_char * 2)
        .replace('%', escape_char + '%')
        .replace('_', escape_char + '_')
    )


def json_sql(value, scalars_to_json=True):
    scalar_convert = sa.text
    if scalars_to_json:
        def scalar_convert(a):
            return sa.func.to_json(sa.text(a))

    if isinstance(value, Mapping):
        return sa.func.json_build_object(
            *(
                json_sql(v, scalars_to_json=False)


## ... source file abbreviated to get to OperationalError examples ...


        text = "SELECT 1 FROM pg_database WHERE datname='%s'" % database
        return bool(get_scalar_result(engine, text))

    elif engine.dialect.name == 'mysql':
        text = ("SELECT SCHEMA_NAME FROM INFORMATION_SCHEMA.SCHEMATA "
                "WHERE SCHEMA_NAME = '%s'" % database)
        return bool(get_scalar_result(engine, text))

    elif engine.dialect.name == 'sqlite':
        if database:
            return database == ':memory:' or sqlite_file_exists(database)
        else:
            return True

    else:
        engine.dispose()
        engine = None
        text = 'SELECT 1'
        try:
            url.database = database
            engine = sa.create_engine(url)
            result = engine.execute(text)
            result.close()
            return True

        except (ProgrammingError, OperationalError):
            return False
        finally:
            if engine is not None:
                engine.dispose()


def create_database(url, encoding='utf8', template=None):

    url = copy(make_url(url))

    database = url.database

    if url.drivername.startswith('postgres'):
        url.database = 'postgres'
    elif url.drivername.startswith('mssql'):
        url.database = 'master'
    elif not url.drivername.startswith('sqlite'):
        url.database = None

    if url.drivername == 'mssql+pyodbc':
        engine = sa.create_engine(url, connect_args={'autocommit': True})
    elif url.drivername == 'postgresql+pg8000':
        engine = sa.create_engine(url, isolation_level='AUTOCOMMIT')
    else:


## ... source file continues with no further OperationalError examples...

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