# Buggy code
def upload_single_file(request, book, book_id):
    # Check and handle Uploaded file
    if "btn-upload-format" in request.files:
        requested_file = request.files["btn-upload-format"]
        # check for empty request
        if requested_file.filename != "":
            if "." in requested_file.filename:
                file_ext = requested_file.filename.rsplit(".", 1)[-1].lower()
                if file_ext not in EXTENSIONS_UPLOAD:
                    flash(
                        _(
                            "File extension '%(ext)s' is not allowed to be uploaded to this server",
                            ext=file_ext,
                        ),
                        category="error",
                    )
                    return redirect(url_for("show_book", book_id=book.id))
            else:
                flash(_("File to be uploaded must have an extension"), category="error")
                return redirect(url_for("show_book", book_id=book.id))

            file_name = book.path.rsplit("/", 1)[-1]
            filepath = os.path.normpath(
                os.path.join(config.config_calibre_dir, book.path)
            )
            saved_filename = os.path.join(filepath, file_name + "." + file_ext)

            # check if file path exists, otherwise create it, copy file to calibre path and delete temp file
            if not os.path.exists(filepath):
                try:
                    os.makedirs(filepath)
                except OSError:
                    flash(
                        _(
                            "Failed to create path %(path)s (Permission denied).",
                            path=filepath,
                        ),
                        category="error",
                    )
                    return redirect(url_for("show_book", book_id=book.id))
            try:
                requested_file.save(saved_filename)
            except OSError:
                flash(
                    _("Failed to store file %(file)s.", file=saved_filename),
                    category="error",
                )
                return redirect(url_for("show_book", book_id=book.id))

            file_size = os.path.getsize(saved_filename)
            is_format = (
                db.session.query(db.Data)
                .filter(db.Data.book == book_id)
                .filter(db.Data.format == file_ext.upper())
                .first()
            )

            # Format entry already exists, no need to update the database
            if is_format:
                app.logger.info("Book format already existing")
            else:
                db_format = db.Data(book_id, file_ext.upper(), file_size, file_name)
                db.session.add(db_format)
                db.session.commit()
                db.session.connection().connection.connection.create_function(
                    "title_sort", 1, db.title_sort
                )

            # Queue uploader info
            uploadText = _(
                "File format %(ext)s added to %(book)s",
                ext=file_ext.upper(),
                book=book.title,
            )
            helper.global_WorkerThread.add_upload(
                current_user.nickname,
                '<a href="'
                + url_for("show_book", book_id=book.id)
                + '">'
                + uploadText
                + "</a>",
            )


# Traceback (OperationalError)
ERROR:cps.web:Exception on /book/125 [GET]
Traceback (most recent call last):
File "/Users/jgillman/Code/calibre-web/vendor/flask/app.py", line 1817, in wsgi_app
response = self.full_dispatch_request()
File "/Users/jgillman/Code/calibre-web/vendor/flask/app.py", line 1477, in full_dispatch_request
rv = self.handle_user_exception(e)
File "/Users/jgillman/Code/calibre-web/vendor/flask/app.py", line 1381, in handle_user_exception
reraise(exc_type, exc_value, tb)
File "/Users/jgillman/Code/calibre-web/vendor/flask/app.py", line 1475, in full_dispatch_request
rv = self.dispatch_request()
File "/Users/jgillman/Code/calibre-web/vendor/flask/app.py", line 1461, in dispatch_request
return self.view_functions[rule.endpoint](**req.view_args)
File "/Users/jgillman/Code/calibre-web/vendor/flask_login.py", line 717, in decorated_view
return func(*args, **kwargs)
File "/Users/jgillman/Code/calibre-web/cps/web.py", line 381, in show_book
return render_template('detail.html', entry=entries,  cc=cc, title=entries.title, books_shelfs=book_in_shelfs)
File "/Users/jgillman/Code/calibre-web/vendor/flask/templating.py", line 128, in render_template
context, ctx.app)
File "/Users/jgillman/Code/calibre-web/vendor/flask/templating.py", line 110, in _render
rv = template.render(context)
File "/Users/jgillman/Code/calibre-web/vendor/jinja2/environment.py", line 969, in render
return self.environment.handle_exception(exc_info, True)
File "/Users/jgillman/Code/calibre-web/vendor/jinja2/environment.py", line 742, in handle_exception
reraise(exc_type, exc_value, tb)
File "/Users/jgillman/Code/calibre-web/cps/templates/detail.html", line 1, in top-level template code
{% extends "layout.html" %}
File "/Users/jgillman/Code/calibre-web/cps/templates/layout.html", line 136, in top-level template code
{% block body %}{% endblock %}
File "/Users/jgillman/Code/calibre-web/cps/templates/detail.html", line 66, in block "body"
{% if entry['custom_column_' ~ c.id]|length > 0 %}
File "/Users/jgillman/Code/calibre-web/vendor/jinja2/environment.py", line 387, in getitem
return getattr(obj, attr)
File "/Users/jgillman/Code/calibre-web/vendor/sqlalchemy/orm/attributes.py", line 316, in __get__
return self.impl.get(instance_state(instance), dict_)
File "/Users/jgillman/Code/calibre-web/vendor/sqlalchemy/orm/attributes.py", line 613, in get
value = self.callable_(state, passive)
File "/Users/jgillman/Code/calibre-web/vendor/sqlalchemy/orm/strategies.py", line 524, in _load_for_state
return self._emit_lazyload(session, state, ident_key, passive)
File "/Users/jgillman/Code/calibre-web/vendor/sqlalchemy/orm/strategies.py", line 585, in _emit_lazyload
result = q.all()
File "/Users/jgillman/Code/calibre-web/vendor/sqlalchemy/orm/query.py", line 2241, in all
return list(self)
File "/Users/jgillman/Code/calibre-web/vendor/sqlalchemy/orm/query.py", line 2353, in __iter__
return self._execute_and_instances(context)
File "/Users/jgillman/Code/calibre-web/vendor/sqlalchemy/orm/query.py", line 2368, in _execute_and_instances
result = conn.execute(querycontext.statement, self._params)
File "/Users/jgillman/Code/calibre-web/vendor/sqlalchemy/engine/base.py", line 662, in execute
params)
File "/Users/jgillman/Code/calibre-web/vendor/sqlalchemy/engine/base.py", line 761, in _execute_clauseelement
compiled_sql, distilled_params
File "/Users/jgillman/Code/calibre-web/vendor/sqlalchemy/engine/base.py", line 874, in _execute_context
context)
File "/Users/jgillman/Code/calibre-web/vendor/sqlalchemy/engine/base.py", line 1024, in _handle_dbapi_exception
exc_info
File "/Users/jgillman/Code/calibre-web/vendor/sqlalchemy/util/compat.py", line 196, in raise_from_cause
reraise(type(exception), exception, tb=exc_tb)
File "/Users/jgillman/Code/calibre-web/vendor/sqlalchemy/engine/base.py", line 867, in _execute_context
context)
File "/Users/jgillman/Code/calibre-web/vendor/sqlalchemy/engine/default.py", line 324, in do_execute
cursor.execute(statement, parameters)
OperationalError: (OperationalError) no such table: books_custom_column_1_link u'SELECT custom_column_1.id AS custom_column_1_id, custom_column_1.value AS custom_column_1_value \
nFROM custom_column_1, books_custom_column_1_link \nWHERE ? = books_custom_column_1_link.book AND custom_column_1.id = books_custom_column_1_link.value' (125,)
ERROR:tornado.access:500 GET /book/125 (::1) 89.60ms

# Fixed code
def upload_single_file(request, book, book_id):
    # Check and handle Uploaded file
    if "btn-upload-format" in request.files:
        requested_file = request.files["btn-upload-format"]
        # check for empty request
        if requested_file.filename != "":
            if "." in requested_file.filename:
                file_ext = requested_file.filename.rsplit(".", 1)[-1].lower()
                if file_ext not in EXTENSIONS_UPLOAD:
                    flash(
                        _(
                            "File extension '%(ext)s' is not allowed to be uploaded to this server",
                            ext=file_ext,
                        ),
                        category="error",
                    )
                    return redirect(url_for("show_book", book_id=book.id))
            else:
                flash(_("File to be uploaded must have an extension"), category="error")
                return redirect(url_for("show_book", book_id=book.id))

            file_name = book.path.rsplit("/", 1)[-1]
            filepath = os.path.normpath(
                os.path.join(config.config_calibre_dir, book.path)
            )
            saved_filename = os.path.join(filepath, file_name + "." + file_ext)

            # check if file path exists, otherwise create it, copy file to calibre path and delete temp file
            if not os.path.exists(filepath):
                try:
                    os.makedirs(filepath)
                except OSError:
                    flash(
                        _(
                            "Failed to create path %(path)s (Permission denied).",
                            path=filepath,
                        ),
                        category="error",
                    )
                    return redirect(url_for("show_book", book_id=book.id))
            try:
                requested_file.save(saved_filename)
            except OSError:
                flash(
                    _("Failed to store file %(file)s.", file=saved_filename),
                    category="error",
                )
                return redirect(url_for("show_book", book_id=book.id))

            file_size = os.path.getsize(saved_filename)
            is_format = (
                db.session.query(db.Data)
                .filter(db.Data.book == book_id)
                .filter(db.Data.format == file_ext.upper())
                .first()
            )

            # Format entry already exists, no need to update the database
            if is_format:
                app.logger.info("Book format already existing")
            else:
                db_format = db.Data(book_id, file_ext.upper(), file_size, file_name)
                db.session.add(db_format)
                db.session.commit()
                db.session.connection().connection.connection.create_function(
                    "title_sort", 1, db.title_sort
                )

            # Queue uploader info
            uploadText = _(
                "File format %(ext)s added to %(book)s",
                ext=file_ext.upper(),
                book=book.title,
            )
            helper.global_WorkerThread.add_upload(
                current_user.nickname,
                '<a href="'
                + url_for("show_book", book_id=book.id)
                + '">'
                + uploadText
                + "</a>",
            )