Re: [sqlalchemy] Problem inserting records in blob column
Hi, I'm experiencing a similar problem in my program (Sqlalchemy 0.8.4).
In my case no blob column is involved, the problem seems to be related to
presence of a foreign key in the target table. Here is the traceback of the
error:
File C:\Python27\lib\site-packages\sqlalchemy\orm\session.py, line 721,
in commit
self.transaction.commit()
File C:\Python27\lib\site-packages\sqlalchemy\orm\session.py, line 354,
in commit
self._prepare_impl()
File C:\Python27\lib\site-packages\sqlalchemy\orm\session.py, line 334,
in _prepare_impl
self.session.flush()
File C:\Python27\lib\site-packages\sqlalchemy\orm\session.py, line
1818, in flush
self._flush(objects)
File C:\Python27\lib\site-packages\sqlalchemy\orm\session.py, line
1936, in _flush
transaction.rollback(_capture_exception=True)
File C:\Python27\lib\site-packages\sqlalchemy\util\langhelpers.py, line
58, in __exit__
compat.reraise(exc_type, exc_value, exc_tb)
File C:\Python27\lib\site-packages\sqlalchemy\orm\session.py, line
1900, in _flush
flush_context.execute()
File C:\Python27\lib\site-packages\sqlalchemy\orm\unitofwork.py, line
372, in execute
rec.execute(self)
File C:\Python27\lib\site-packages\sqlalchemy\orm\unitofwork.py, line
525, in execute
uow
File C:\Python27\lib\site-packages\sqlalchemy\orm\persistence.py, line
64, in save_obj
table, insert)
File C:\Python27\lib\site-packages\sqlalchemy\orm\persistence.py, line
569, in _emit_insert_statements
execute(statement, params)
File C:\Python27\lib\site-packages\sqlalchemy\engine\base.py, line 662,
in execute
params)
File C:\Python27\lib\site-packages\sqlalchemy\engine\base.py, line 761,
in _execute_clauseelement
compiled_sql, distilled_params
File C:\Python27\lib\site-packages\sqlalchemy\engine\base.py, line 828,
in _execute_context
None, None)
File C:\Python27\lib\site-packages\sqlalchemy\engine\base.py, line
1024, in _handle_dbapi_exception
exc_info
File C:\Python27\lib\site-packages\sqlalchemy\util\compat.py, line 196,
in raise_from_cause
reraise(type(exception), exception, tb=exc_tb)
File C:\Python27\lib\site-packages\sqlalchemy\engine\base.py, line 824,
in _execute_context
context = constructor(dialect, self, conn, *args)
File C:\Python27\lib\site-packages\sqlalchemy\engine\default.py, line
446, in _init_compiled
self.__process_defaults()
File C:\Python27\lib\site-packages\sqlalchemy\engine\default.py, line
821, in __process_defaults
val = self.get_insert_default(c)
File C:\Python27\lib\site-packages\sqlalchemy\engine\default.py, line
777, in get_insert_default
return self._exec_default(column.default, column.type)
File C:\Python27\lib\site-packages\sqlalchemy\engine\default.py, line
761, in _exec_default
return self.fire_sequence(default, type_)
StatementError: 'SQLiteExecutionContext' object has no attribute
'fire_sequence' (original cause: AttributeError: 'SQLiteExecutionContext'
object has no attribute 'fire_sequence') u'INSERT INTO dataset (set_id,
user_id, label, set_table, nam_table, val_table, datasource, info) VALUES
(?, ?, ?, ?, ?, ?, ?, ?)' [{'info': None, 'user_id': 1, 'val_table':
u'val_table', 'label': u'tab1', 'nam_tab': u'nam_table', 'set_table':
u'tab1', 'datasource': None}]
The construct which causes the error is this:
dataset.append_constraint(sa.ForeignKeyConstraint([dataset.c.set_id],
[task.c.set_id]))
If I remove this line of code everything goes well (but of course I cannot
set up the relationship between the dataset table and the task table).
Any help is really appreciated.
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Re: [sqlalchemy] How to declare a custom type that will imply a check on a column?
The example works wonderfully,
however i noticed, that when i attach a constraint to the column, it gets
mirrored in the table
so the event handler
@event.listens_for(PString, after_parent_attach)
def create_constraint(target, parent):
@event.listens_for(parent, after_parent_attach)
def add_to_table(col, table):
col.constraints.add(CheckConstraint(parent != ''))
will result in
CREATE TABLE fun (
name VARCHAR(100) CHECK (name != ''),
CHECK (name != '')
)
instead of
CREATE TABLE fun (
name VARCHAR(100) CHECK (name != '')
)
when using
m = MetaData()
t = Table(
'fun', m,
Column('name', PString(100)),
)
e = create_engine('sqlite://', echo=1)
m.create_all(e)
m.drop_all(e)
assert 0
On Wednesday, December 18, 2013 5:26:53 PM UTC+1, Michael Bayer wrote:
On Dec 18, 2013, at 5:41 AM, RonnyPfannschmidt
ronny.pfa...@gmail.comjavascript:
wrote:
Hi,
for supporting a certain schema requirement,
i have to create a quite a number of columns that are checked not to be
a empty string,
So i'd like to declare a custom type, which will automatically imply the
check on those columns.
I already Investigated, how Boolean does this for databases with
non-native boolean types,
however it uses number private methods,
Should i follow its example or is there a official way?
what i currently have to do is
Column('foo', String(20), CheckConstraint(foo '')
what i'd like use is something like
Column('foo', PString(20))
you’d use a TypeDecorator for this. See the example
http://docs.sqlalchemy.org/en/rel_0_9/core/types.html#coercing-encoded-strings-to-unicodefor
something similar (coerces to utf-8, just replace that with checking
for non-empty).
--
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Re: [sqlalchemy] How to declare a custom type that will imply a check on a column?
i discovered a workaround
by doing
@event.listens_for(PString, after_parent_attach)
def create_constraint(target, parent):
@event.listens_for(parent, after_parent_attach)
def add_to_table(col, table):
constraint = CheckConstraint(column(col.name) != text(''),
_autoattach=False)
constraint.parent = col
col.constraints.add(constraint)
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Re: [sqlalchemy] Problem inserting records in blob column
there’s a SQLAlchemy issue here, marked as ticket
http://www.sqlalchemy.org/trac/ticket/2896, however resolving this issue still
won’t fix your issue. You’re emitting an INSERT on a table where the primary
key needs to refer to a column elsewhere. that is:
task = Table('y', metadata,
Column('set_id', Integer, primary_key=True)
)
dataset = Table(x, metadata,
Column(set_id, Integer, primary_key=True)
)
dataset.append_constraint(ForeignKeyConstraint([dataset.c.set_id],
[task.c.set_id]))
to insert a dataset row, the dataset must refer to a task row. SQLite doesn’t
enforce foreign key constraints by default so that the INSERT will proceed but
the row will be relationally inconsistent.
also, if you aren’t planning on using Oracle as a backend, I’d remove the
Sequence directive from your program for now. until #2896 is fixed it will
get in the way of allowing this issue to be clear.
On Dec 20, 2013, at 5:50 AM, Massi massi_...@msn.com wrote:
Hi, I'm experiencing a similar problem in my program (Sqlalchemy 0.8.4). In
my case no blob column is involved, the problem seems to be related to
presence of a foreign key in the target table. Here is the traceback of the
error:
File C:\Python27\lib\site-packages\sqlalchemy\orm\session.py, line 721,
in commit
self.transaction.commit()
File C:\Python27\lib\site-packages\sqlalchemy\orm\session.py, line 354,
in commit
self._prepare_impl()
File C:\Python27\lib\site-packages\sqlalchemy\orm\session.py, line 334,
in _prepare_impl
self.session.flush()
File C:\Python27\lib\site-packages\sqlalchemy\orm\session.py, line 1818,
in flush
self._flush(objects)
File C:\Python27\lib\site-packages\sqlalchemy\orm\session.py, line 1936,
in _flush
transaction.rollback(_capture_exception=True)
File C:\Python27\lib\site-packages\sqlalchemy\util\langhelpers.py, line
58, in __exit__
compat.reraise(exc_type, exc_value, exc_tb)
File C:\Python27\lib\site-packages\sqlalchemy\orm\session.py, line 1900,
in _flush
flush_context.execute()
File C:\Python27\lib\site-packages\sqlalchemy\orm\unitofwork.py, line
372, in execute
rec.execute(self)
File C:\Python27\lib\site-packages\sqlalchemy\orm\unitofwork.py, line
525, in execute
uow
File C:\Python27\lib\site-packages\sqlalchemy\orm\persistence.py, line
64, in save_obj
table, insert)
File C:\Python27\lib\site-packages\sqlalchemy\orm\persistence.py, line
569, in _emit_insert_statements
execute(statement, params)
File C:\Python27\lib\site-packages\sqlalchemy\engine\base.py, line 662,
in execute
params)
File C:\Python27\lib\site-packages\sqlalchemy\engine\base.py, line 761,
in _execute_clauseelement
compiled_sql, distilled_params
File C:\Python27\lib\site-packages\sqlalchemy\engine\base.py, line 828,
in _execute_context
None, None)
File C:\Python27\lib\site-packages\sqlalchemy\engine\base.py, line 1024,
in _handle_dbapi_exception
exc_info
File C:\Python27\lib\site-packages\sqlalchemy\util\compat.py, line 196,
in raise_from_cause
reraise(type(exception), exception, tb=exc_tb)
File C:\Python27\lib\site-packages\sqlalchemy\engine\base.py, line 824,
in _execute_context
context = constructor(dialect, self, conn, *args)
File C:\Python27\lib\site-packages\sqlalchemy\engine\default.py, line
446, in _init_compiled
self.__process_defaults()
File C:\Python27\lib\site-packages\sqlalchemy\engine\default.py, line
821, in __process_defaults
val = self.get_insert_default(c)
File C:\Python27\lib\site-packages\sqlalchemy\engine\default.py, line
777, in get_insert_default
return self._exec_default(column.default, column.type)
File C:\Python27\lib\site-packages\sqlalchemy\engine\default.py, line
761, in _exec_default
return self.fire_sequence(default, type_)
StatementError: 'SQLiteExecutionContext' object has no attribute
'fire_sequence' (original cause: AttributeError: 'SQLiteExecutionContext'
object has no attribute 'fire_sequence') u'INSERT INTO dataset (set_id,
user_id, label, set_table, nam_table, val_table, datasource, info) VALUES (?,
?, ?, ?, ?, ?, ?, ?)' [{'info': None, 'user_id': 1, 'val_table':
u'val_table', 'label': u'tab1', 'nam_tab': u'nam_table', 'set_table':
u'tab1', 'datasource': None}]
The construct which causes the error is this:
dataset.append_constraint(sa.ForeignKeyConstraint([dataset.c.set_id],
[task.c.set_id]))
If I remove this line of code everything goes well (but of course I cannot
set up the relationship between the dataset table and the task table).
Any help is really appreciated.
--
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To unsubscribe from this group and stop receiving emails from it, send an
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Visit
Re: [sqlalchemy] Problem inserting records in blob column
issue #2896 is resolved for 0.8.5 and 0.9.0.
On Dec 20, 2013, at 10:03 AM, Michael Bayer mike...@zzzcomputing.com wrote:
there’s a SQLAlchemy issue here, marked as ticket
http://www.sqlalchemy.org/trac/ticket/2896, however resolving this issue
still won’t fix your issue. You’re emitting an INSERT on a table where the
primary key needs to refer to a column elsewhere. that is:
task = Table('y', metadata,
Column('set_id', Integer, primary_key=True)
)
dataset = Table(x, metadata,
Column(set_id, Integer, primary_key=True)
)
dataset.append_constraint(ForeignKeyConstraint([dataset.c.set_id],
[task.c.set_id]))
to insert a dataset row, the dataset must refer to a task row. SQLite
doesn’t enforce foreign key constraints by default so that the INSERT will
proceed but the row will be relationally inconsistent.
also, if you aren’t planning on using Oracle as a backend, I’d remove the
Sequence directive from your program for now. until #2896 is fixed it will
get in the way of allowing this issue to be clear.
On Dec 20, 2013, at 5:50 AM, Massi massi_...@msn.com wrote:
Hi, I'm experiencing a similar problem in my program (Sqlalchemy 0.8.4). In
my case no blob column is involved, the problem seems to be related to
presence of a foreign key in the target table. Here is the traceback of the
error:
File C:\Python27\lib\site-packages\sqlalchemy\orm\session.py, line 721,
in commit
self.transaction.commit()
File C:\Python27\lib\site-packages\sqlalchemy\orm\session.py, line 354,
in commit
self._prepare_impl()
File C:\Python27\lib\site-packages\sqlalchemy\orm\session.py, line 334,
in _prepare_impl
self.session.flush()
File C:\Python27\lib\site-packages\sqlalchemy\orm\session.py, line 1818,
in flush
self._flush(objects)
File C:\Python27\lib\site-packages\sqlalchemy\orm\session.py, line 1936,
in _flush
transaction.rollback(_capture_exception=True)
File C:\Python27\lib\site-packages\sqlalchemy\util\langhelpers.py, line
58, in __exit__
compat.reraise(exc_type, exc_value, exc_tb)
File C:\Python27\lib\site-packages\sqlalchemy\orm\session.py, line 1900,
in _flush
flush_context.execute()
File C:\Python27\lib\site-packages\sqlalchemy\orm\unitofwork.py, line
372, in execute
rec.execute(self)
File C:\Python27\lib\site-packages\sqlalchemy\orm\unitofwork.py, line
525, in execute
uow
File C:\Python27\lib\site-packages\sqlalchemy\orm\persistence.py, line
64, in save_obj
table, insert)
File C:\Python27\lib\site-packages\sqlalchemy\orm\persistence.py, line
569, in _emit_insert_statements
execute(statement, params)
File C:\Python27\lib\site-packages\sqlalchemy\engine\base.py, line 662,
in execute
params)
File C:\Python27\lib\site-packages\sqlalchemy\engine\base.py, line 761,
in _execute_clauseelement
compiled_sql, distilled_params
File C:\Python27\lib\site-packages\sqlalchemy\engine\base.py, line 828,
in _execute_context
None, None)
File C:\Python27\lib\site-packages\sqlalchemy\engine\base.py, line 1024,
in _handle_dbapi_exception
exc_info
File C:\Python27\lib\site-packages\sqlalchemy\util\compat.py, line 196,
in raise_from_cause
reraise(type(exception), exception, tb=exc_tb)
File C:\Python27\lib\site-packages\sqlalchemy\engine\base.py, line 824,
in _execute_context
context = constructor(dialect, self, conn, *args)
File C:\Python27\lib\site-packages\sqlalchemy\engine\default.py, line
446, in _init_compiled
self.__process_defaults()
File C:\Python27\lib\site-packages\sqlalchemy\engine\default.py, line
821, in __process_defaults
val = self.get_insert_default(c)
File C:\Python27\lib\site-packages\sqlalchemy\engine\default.py, line
777, in get_insert_default
return self._exec_default(column.default, column.type)
File C:\Python27\lib\site-packages\sqlalchemy\engine\default.py, line
761, in _exec_default
return self.fire_sequence(default, type_)
StatementError: 'SQLiteExecutionContext' object has no attribute
'fire_sequence' (original cause: AttributeError: 'SQLiteExecutionContext'
object has no attribute 'fire_sequence') u'INSERT INTO dataset (set_id,
user_id, label, set_table, nam_table, val_table, datasource, info) VALUES
(?, ?, ?, ?, ?, ?, ?, ?)' [{'info': None, 'user_id': 1, 'val_table':
u'val_table', 'label': u'tab1', 'nam_tab': u'nam_table', 'set_table':
u'tab1', 'datasource': None}]
The construct which causes the error is this:
dataset.append_constraint(sa.ForeignKeyConstraint([dataset.c.set_id],
[task.c.set_id]))
If I remove this line of code everything goes well (but of course I cannot
set up the relationship between the dataset table and the task table).
Any help is really appreciated.
--
You received this message because you are subscribed to the Google Groups
sqlalchemy group.
To unsubscribe from this group and stop receiving
Re: [sqlalchemy] How to declare a custom type that will imply a check on a column?
On Dec 20, 2013, at 8:45 AM, RonnyPfannschmidt ronny.pfannschm...@gmail.com
wrote:
The example works wonderfully,
however i noticed, that when i attach a constraint to the column, it gets
mirrored in the table
so the event handler
@event.listens_for(PString, after_parent_attach)
def create_constraint(target, parent):
@event.listens_for(parent, after_parent_attach)
def add_to_table(col, table):
col.constraints.add(CheckConstraint(parent != '’))
use:
table.append_constraint(CheckConstraint(parent != '’))
the constraints collection on the Column is handled by the internals.
will result in
CREATE TABLE fun (
name VARCHAR(100) CHECK (name != ''),
CHECK (name != '')
)
instead of
CREATE TABLE fun (
name VARCHAR(100) CHECK (name != '')
)
when using
m = MetaData()
t = Table(
'fun', m,
Column('name', PString(100)),
)
e = create_engine('sqlite://', echo=1)
m.create_all(e)
m.drop_all(e)
assert 0
On Wednesday, December 18, 2013 5:26:53 PM UTC+1, Michael Bayer wrote:
On Dec 18, 2013, at 5:41 AM, RonnyPfannschmidt ronny.pfa...@gmail.com
wrote:
Hi,
for supporting a certain schema requirement,
i have to create a quite a number of columns that are checked not to be a
empty string,
So i'd like to declare a custom type, which will automatically imply the
check on those columns.
I already Investigated, how Boolean does this for databases with non-native
boolean types,
however it uses number private methods,
Should i follow its example or is there a official way?
what i currently have to do is
Column('foo', String(20), CheckConstraint(foo '')
what i'd like use is something like
Column('foo', PString(20))
you’d use a TypeDecorator for this. See the example
http://docs.sqlalchemy.org/en/rel_0_9/core/types.html#coercing-encoded-strings-to-unicode
for something similar (coerces to utf-8, just replace that with checking for
non-empty).
--
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