[sqlalchemy] Re: Updating field by applying transformation function to current field value
Many thanks. Great help.
On Jun 9, 4:44 pm, Conor conor.edward.da...@gmail.com wrote:
On 06/09/2010 07:58 AM, bartomas wrote:
Hi,
I'm new to SqlAlchemy. I'd like to find the simplest way of updating
the fields of a table by applying a transformation function to the
current value of the field.
I've tried the following:
## Code snippet
engine = create_engine('mysql://root:t...@localhost:3306/Test1')
metadata = MetaData()
metadata.bind = engine
employees = Table('employees', metadata, autoload=True)
upd =
employees.update(values={employees.c.fullname:transform2(employees.c.fullname)})
engine.execute(upd)
def transform2(currentValue):
return re.sub('Peter','Paul',currentValue)
def transform1(currentValue):
return 'Mr ' + currentValue
## end code snippet
When applying the function transform1 which just concatenates another
string to the current value, it works fine. However if I apply
transform2 that does a regular expression substitution on the value I
get an error message saying that the re.sub function expects a string
argument.
How can I retrieve the current value from a Column object to transform
it? Or is there a better way to this problem?
Many thanks for any help.
In both transform functions, currentValue is the column object, not the
value for a particular row. transform1 happens to work because column
objects can turn the + operator into a SQL expression. To get the same
effect for transform2, you have to use database functions, e.g. for
PostgreSQL:
upd = employees.update(values={employees.c.fullname:
func.regex_replace(employees.c.fullname, 'Peter', 'Paul')})
If the transform function really does have to be run client-side, you
have no choice but to SELECT all the rows, apply the transform, and
issue many UPDATEs back to the database. Using the ORM can make this easier.
-Conor
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Re: [sqlalchemy] Some weir(for me) behavior of one-to-one relation.
I have 2 tables with one-to-one relation, and I got some unexpected
behaviour from sqlalchemy.
In attach there is demonstration script and its log.
If I try to add object into table right for already existing key I
expect error on DB level, telling about violation of unique
constraint, but sqlalchemy before try to insert new row, set relation
key to NULL for already existing object...
Is it right?
How can I avoid such behavior?
if you are replacing an object reference with another one, then yes SQLA will
null out the key for the old one first, since you have removed it from its
parent by replacing it. If you dont want the NULL allowed, the usual
approach is to have the left_idnr column be NOT NULL - the database then does
the work of disallowing the operation to proceed. There is a setting for
passive_deletes, 'all', which disallows the nulling out of the foreign key,
but that only applies to a cascading deletion scenario which is not the case
here.
For one-to-ones I usually set the foreign key on the child as the primary key
as well. You can see me asking about this (since a DBA gave me some
resistance about it recently) here:
http://stackoverflow.com/questions/2967450/foreign-key-constraints-on-primary-key-columns-issues
I try to change schema(updated example in attach, it drop
AssertionException), to use foreign key as primary key for child
table, but it doesn't want to work in this configuration at all.
Please give me link on sqlalchemy documentation, where I can read
about such usage of primary key.
There is only one place in sqlalchemy documentation where I see such
usage of primary key
http://www.sqlalchemy.org/docs/05/reference/ext/declarative.html?highlight=declarative#joined-table-inheritance
but this is not my case.
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#!/usr/bin/env python
#-*- coding:utf-8 -*-
#import pdb
import os, sys
import time
import logging
#import re
#import errno
#import locale
#import pprint
# mutable inputs
from sqlalchemy import *
from sqlalchemy import orm
from sqlalchemy.ext.declarative import declarative_base
decl = declarative_base()
class left(decl):
__tablename__ = 'left'
idnr= Column(Integer, primary_key=True)
data= Column(String(32), nullable=False)
rel = orm.relation('right', uselist=False,
backref=orm.backref('left'),
passive_updates=True, passive_deletes=True, lazy=True, cascade='all')
class right(decl):
__tablename__ = 'right'
#idnr= Column(Integer, primary_key=True)
left_idnr = Column(Integer, ForeignKey(left.idnr, onupdate='CASCADE', ondelete='CASCADE'), primary_key=True, unique=True)
data= Column(String(32), nullable=False)
def main():
logging.basicConfig()
log = logging.getLogger('sqlalchemy.engine')
log.setLevel(logging.DEBUG)
eng = create_engine('sqlite://')
sm = orm.sessionmaker(bind=eng, autoflush=False, autocommit=False)
decl.metadata.create_all(eng)
ses = sm()
l = left()
l.data = 'abc'
ses.add(l)
r = right()
r.left = l
r.data = 'cde'
ses.add(r)
ses.commit()
l_idnr = l.idnr
ses.close()
ses = sm()
l = ses.query(left).get(l_idnr)
r2 = right()
r2.left = l
r2.data = '012'
ses.flush()
ses.commit()
if __name__ == '__main__':
main()
[sqlalchemy] help please
Hello All,
I just began learning sqlalchemy and am not quite used to it yet so
please excuse my ignorance and which might be a trivial question to
some of you.
I am writing a database module and need to load a table and possibly
modify a record in the table. I can get the connection established and
everything works fine. The problem I am running into is that I do not
necessarily know the column name before hand to code it in the update
method. I want to be able to find out to send a generic column name
which will be updated (gets the column name dynamically).
I tried the following:
columns=['ProjectID', 'Program', 'progmanger']
test = str('table.c.'+columns[1])
update = table.update(test=='project-name', values = {test:'program'})
print update
update.execute()
I get a error when I try to run it. It does not recognize the column
for some reason even though if I print test everything seems to be OK.
I get 'project.c.Program'
Is there something I am missing here? How can I send the project and
column name to the update method dynamically?
Thank you so much in advance for any help or insight you could provide.
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[sqlalchemy] good IDE for SQLAlchemy and wxPython?
G'day, I'm developing my first desktop application with python and a database (to track cycling track sprinters, if anyone's interested, using sqlite at the moment, but anything lightweight is fine) - and have been poking around various IDE's and database layers that work with Python, SQLAlchemy seems to be the neatest way to tie a class to a database without having to manually do all the database 'stuff' by using the ORM. If only this stuff existed back when I was at Uni and trying to work out how to save a C structure, wow .. but anyway .. ! I've found Pythoncard as an IDE and toolkit, but it seems a bit inactive, I'm developing on Windows XP 32 bit and am wondering what sort of IDE works well with SQLAlchemy and wxPython? Should I just use the pythoncard editor (which works well enough as an editor but the whole setup of GUIs in template files is something I'm unsure about) or is there a better alternative? I'm using wxGlade to mockup my interfaces and then copying the bits it generates into my program, but am wondering if there's any SQLAlchemy-aware IDE's that might speed up making forms and so on, rather than coding them all by hand? -- You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalch...@googlegroups.com. To unsubscribe from this group, send email to sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en.
RE: [sqlalchemy] Sybase reports conversion from datatype 'CHAR' to 'INT' is not allowed. when using string instead of int for filterby
SQLAlchemy doesn't do type coercion out of the box. Some DBAPIs do, which is why you may have not noticed this issue on other platforms. You can build that functionality yourself using TypeDecorator: http://www.sqlalchemy.org/docs/reference/sqlalchemy/types.htm?highlight=typedecorator#sqlalchemy.types.TypeDecorator I've fixed my problem with the TypeDecorator you suggested. Thanks. Just to fix that, sqlalchemy doesn't do type coercion by default, and it will never do it. Is it correct? In my test application I was able to replace the Integer type to the decorated one, which is fine, but requires the same 4-line code for my projects. It would be better if sqlalchemy would do it for me by default but if it doesn't fit to the design I can accept that. Thanks, Zsolt -- NOTICE: If received in error, please destroy, and notify sender. Sender does not intend to waive confidentiality or privilege. Use of this email is prohibited when received in error. We may monitor and store emails to the extent permitted by applicable law. -- You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalch...@googlegroups.com. To unsubscribe from this group, send email to sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en.
[sqlalchemy] Kerberos authentication with sybase
Hi all, Is there any plan to add kerberos authentication to the sybase engine in sqlalchemy? I've implemented it but it's using the creator parameter of the create_engine function, which is ok, but in certain circumstances when the application using sqlalchemy uses configuration from a text file, I'm not able to do it easily (in pylons I need to modify my templates, or add a bunch of code to each project). It would be nice if sqlalchemy would be able to accept the server's principal specified in the connection string somehow - and if it's specified use kerberos to authenticate the client. Is it possible to implement this modification in sqlalchemy? I'm happy to contribute my current implementation. Thanks, Zsolt -- NOTICE: If received in error, please destroy, and notify sender. Sender does not intend to waive confidentiality or privilege. Use of this email is prohibited when received in error. We may monitor and store emails to the extent permitted by applicable law. -- You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalch...@googlegroups.com. To unsubscribe from this group, send email to sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en.
[sqlalchemy] Re: help please
you should access column names via lower case
i.e.
columns = 'projectid', 'program', 'progmanger']
On 10 Jun, 03:39, Aref arefnamm...@gmail.com wrote:
Hello All,
I just began learning sqlalchemy and am not quite used to it yet so
please excuse my ignorance and which might be a trivial question to
some of you.
I am writing a database module and need to load a table and possibly
modify a record in the table. I can get the connection established and
everything works fine. The problem I am running into is that I do not
necessarily know the column name before hand to code it in the update
method. I want to be able to find out to send a generic column name
which will be updated (gets the column name dynamically).
I tried the following:
columns=['ProjectID', 'Program', 'progmanger']
test = str('table.c.'+columns[1])
update = table.update(test=='project-name', values = {test:'program'})
print update
update.execute()
I get a error when I try to run it. It does not recognize the column
for some reason even though if I print test everything seems to be OK.
I get 'project.c.Program'
Is there something I am missing here? How can I send the project and
column name to the update method dynamically?
Thank you so much in advance for any help or insight you could provide.
--
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Re: [sqlalchemy] good IDE for SQLAlchemy and wxPython?
Carl, On 10/06/2010 08:17, Carl Brewer wrote: G'day, I'm developing my first desktop application with python and a database (to track cycling track sprinters, if anyone's interested, using sqlite at the moment, but anything lightweight is fine) - and have been poking around various IDE's and database layers that work with Python, SQLAlchemy seems to be the neatest way to tie a class to a database without having to manually do all the database 'stuff' by using the ORM. If only this stuff existed back when I was at Uni and trying to work out how to save a C structure, wow .. but anyway .. ! I've found Pythoncard as an IDE and toolkit, but it seems a bit inactive, I'm developing on Windows XP 32 bit and am wondering what sort of IDE works well with SQLAlchemy and wxPython? Should I just use the pythoncard editor (which works well enough as an editor but the whole setup of GUIs in template files is something I'm unsure about) or is there a better alternative? I'm using wxGlade to mockup my interfaces and then copying the bits it generates into my program, but am wondering if there's any SQLAlchemy-aware IDE's that might speed up making forms and so on, rather than coding them all by hand? That would be nice but I am not aware of one. Personally I use Boa to develop, it has a GUI designer built in you can use to generate the dialogs/frames etc and I then use validators to load data to/from the controls. Dabo (http://www.dabodev.com/) might also be an alternative you want to look at, also it has is own db access stuff - I asked in the past if they don't want to switch to SA but there doesn't seem to be any interest in doing this. Werner -- You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalch...@googlegroups.com. To unsubscribe from this group, send email to sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en.
Re: [sqlalchemy] Having case problem with column name in postgresql
On Jun 10, 2010, at 12:06 AM, Mike Bernson wrote:
I am trying to access a postgres database with mixed case column names.
I am using reflection to get the table.
Here is my connect string:
'postgresql://:mike@/cedar_senior_services'
The error message:
(ProgrammingError) column active does not exist
LINE 1: select * from license where Active=E'yes' and LicenseType=E'...
^
'select * from license where Active=%(Active)s and
LicenseType=%(LicenseType)s' {'Active': 'yes', 'LicenseType': 'ADMIN'}
The error message is correct that active does not exist but Active is the
requested column.
How do I get sqlalchemy when using postgres to quote thing so that looks for
same case column names.
Using Sqlalchemy 6.1 with postgres 8.4.4
The follow selection does work:
select * from license where Active='yes' and LicenseType='ADMIN';
Since this is my first try as using postgres from sqlalchemy I am sure that
I must by missing something simple on the connection url or create engine.
any column name with capital letters in it will be quoted in all cases. If
you are using table metadata and its spitting out Active without quotes,
thats a huge bug, although above that looks like a hand-coded statement.
Using a table with a column named Active I get:
SELECT t1.Active FROM t1
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Re: [sqlalchemy] Sybase reports conversion from datatype 'CHAR' to 'INT' is not allowed. when using string instead of int for filterby
On Jun 10, 2010, at 8:51 AM, Cserna, Zsolt wrote: SQLAlchemy doesn't do type coercion out of the box. Some DBAPIs do, which is why you may have not noticed this issue on other platforms. You can build that functionality yourself using TypeDecorator: http://www.sqlalchemy.org/docs/reference/sqlalchemy/types.htm?highlight=typedecorator#sqlalchemy.types.TypeDecorator I've fixed my problem with the TypeDecorator you suggested. Thanks. Just to fix that, sqlalchemy doesn't do type coercion by default, and it will never do it. Is it correct? In my test application I was able to replace the Integer type to the decorated one, which is fine, but requires the same 4-line code for my projects. It would be better if sqlalchemy would do it for me by default but if it doesn't fit to the design I can accept that. from string- something is not always a clean cut affair (though it is for int()) , but it also adds overhead to the usage of bind parameters, which can add up if you're doing an executemany() style call with thousands of parameter sets. Its better that this additional behavior is left up to extensions. Any non-trivial SQLAlchemy project would usually have a util.py of some sort that contains a set of SQLAlchemy idioms for usage throughout the application. In mine I usually have a whole set of types that are specific to the use case at hand, column-generating macros that enforce naming schemes, stuff like that. -- You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalch...@googlegroups.com. To unsubscribe from this group, send email to sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en.
Re: [sqlalchemy] Kerberos authentication with sybase
if you want to show me how that's done with your DBAPI (what DBAPI is this?), sure, though if its something that you pass in via **kw to DBAPI.connect(), you can already do that by passing connect_args to create_engine(), or adding them onto the querystring db://...?foo=bar. On Jun 10, 2010, at 9:10 AM, Cserna, Zsolt wrote: Hi all, Is there any plan to add kerberos authentication to the sybase engine in sqlalchemy? I've implemented it but it's using the creator parameter of the create_engine function, which is ok, but in certain circumstances when the application using sqlalchemy uses configuration from a text file, I'm not able to do it easily (in pylons I need to modify my templates, or add a bunch of code to each project). It would be nice if sqlalchemy would be able to accept the server's principal specified in the connection string somehow - and if it's specified use kerberos to authenticate the client. Is it possible to implement this modification in sqlalchemy? I'm happy to contribute my current implementation. Thanks, Zsolt -- NOTICE: If received in error, please destroy, and notify sender. Sender does not intend to waive confidentiality or privilege. Use of this email is prohibited when received in error. We may monitor and store emails to the extent permitted by applicable law. -- You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalch...@googlegroups.com. To unsubscribe from this group, send email to sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en. -- You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalch...@googlegroups.com. To unsubscribe from this group, send email to sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en.
[sqlalchemy] Re: help please
Thank you for the response. However, that is not the problem. If I do
update = table.update(project.c.ProjectID=='project-name', values =
{project.c.ProjectID:'program'})
print update
update.execute()
everything works fine.
if I do this:
test = 'table.c.'+columns[0] #columns is a list which contains the
columns names
update = table.update(test == 'project-name', values={test:'program'})
update.execute()
it does not work. I get an error that there is no such column.
I need to be able to update columns dynamically where I do not have a
prior knowledge of what tables and what are the table columns that may
exist. How can I do that if at all?
On Jun 10, 7:21 am, GHZ geraint.willi...@gmail.com wrote:
you should access column names via lower case
i.e.
columns = 'projectid', 'program', 'progmanger']
On 10 Jun, 03:39, Aref arefnamm...@gmail.com wrote:
Hello All,
I just began learning sqlalchemy and am not quite used to it yet so
please excuse my ignorance and which might be a trivial question to
some of you.
I am writing a database module and need to load a table and possibly
modify a record in the table. I can get the connection established and
everything works fine. The problem I am running into is that I do not
necessarily know the column name before hand to code it in the update
method. I want to be able to find out to send a generic column name
which will be updated (gets the column name dynamically).
I tried the following:
columns=['ProjectID', 'Program', 'progmanger']
test = str('table.c.'+columns[1])
update = table.update(test=='project-name', values = {test:'program'})
print update
update.execute()
I get a error when I try to run it. It does not recognize the column
for some reason even though if I print test everything seems to be OK.
I get 'project.c.Program'
Is there something I am missing here? How can I send the project and
column name to the update method dynamically?
Thank you so much in advance for any help or insight you could provide.-
Hide quoted text -
- Show quoted text -
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RE: [sqlalchemy] help please
-Original Message-
From: sqlalchemy@googlegroups.com
[mailto:sqlalch...@googlegroups.com] On Behalf Of Aref
Sent: 10 June 2010 02:40
To: sqlalchemy
Subject: [sqlalchemy] help please
Hello All,
I just began learning sqlalchemy and am not quite used to it yet so
please excuse my ignorance and which might be a trivial question to
some of you.
I am writing a database module and need to load a table and possibly
modify a record in the table. I can get the connection established and
everything works fine. The problem I am running into is that I do not
necessarily know the column name before hand to code it in the update
method. I want to be able to find out to send a generic column name
which will be updated (gets the column name dynamically).
I tried the following:
columns=['ProjectID', 'Program', 'progmanger']
test = str('table.c.'+columns[1])
update = table.update(test=='project-name', values = {test:'program'})
print update
update.execute()
I get a error when I try to run it. It does not recognize the column
for some reason even though if I print test everything seems to be OK.
I get 'project.c.Program'
Is there something I am missing here? How can I send the project and
column name to the update method dynamically?
Thank you so much in advance for any help or insight you
could provide.
The table.c object supports dictionary-style access, so you should be
able to use something like this:
colname = 'Program'
column = table.c[colname]
update = table.update(column=='project-name', values =
{test:'program'})
However, in general, if you want to get a named attribute of an object,
and the name is stored in a variable, you can use Python's getattr
function. This code should also work:
colname = 'Program'
column = getattr(table.c, colname)
update = table.update(column=='project-name', values =
{test:'program'})
Hope that helps,
Simon
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Re: [sqlalchemy] Re: help please
On 6/10/2010 10:29 AM, Aref wrote:
Thank you for the response. However, that is not the problem. If I do
update = table.update(project.c.ProjectID=='project-name', values =
{project.c.ProjectID:'program'})
print update
update.execute()
everything works fine.
if I do this:
test = 'table.c.'+columns[0] #columns is a list which contains the
columns names
update = table.update(test == 'project-name', values={test:'program'})
update.execute()
it does not work. I get an error that there is no such column.
I need to be able to update columns dynamically where I do not have a
prior knowledge of what tables and what are the table columns that may
exist. How can I do that if at all?
Instead try:
update = table.update(eval(test)=='project-name',
values={test:'program'})
I can't say for sure that's the best way to do it still, but it
would solve your immediate problem. The "test" variable is referencing
a string, not a column. You have to eval() it to get the column
reference.
However, you say your error is that "there is no such column" ... I'd
expect a much different error if my suggestion were to actually fix
your problem. Anyway good luck. :) Might include your traceback next
time if you still have problems.
Lance
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Re: [sqlalchemy] Having case problem with column name in postgresql
Michael Bayer wrote:
On Jun 10, 2010, at 12:06 AM, Mike Bernson wrote:
I am trying to access a postgres database with mixed case column names.
I am using reflection to get the table.
Here is my connect string:
'postgresql://:mike@/cedar_senior_services'
The error message:
(ProgrammingError) column active does not exist
LINE 1: select * from license where Active=E'yes' and LicenseType=E'...
^
'select * from license where Active=%(Active)s and LicenseType=%(LicenseType)s'
{'Active': 'yes', 'LicenseType': 'ADMIN'}
The error message is correct that active does not exist but Active is the
requested column.
How do I get sqlalchemy when using postgres to quote thing so that looks for
same case column names.
Using Sqlalchemy 6.1 with postgres 8.4.4
The follow selection does work:
select * from license where Active='yes' and LicenseType='ADMIN';
Since this is my first try as using postgres from sqlalchemy I am sure that
I must by missing something simple on the connection url or create engine.
any column name with capital letters in it will be quoted in all cases. If you are using table metadata and its spitting out Active without quotes, thats a huge bug, although above that looks like a hand-coded statement.
Using a table with a column named Active I get:
SELECT t1.Active FROM t1
I did some more hunting based on reply and did find that the query where
clause is coming from text strings and not metadata.
Thanks for the quick reply.
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[sqlalchemy] Re: help please
Thank you very much. I'll try it. Is there a better way of doing this--
I mean there must be since this is necessary for any application
needing to modify a database where generally tables are accessed
dynamically.
On Jun 10, 9:37 am, Lance Edgar lance.ed...@gmail.com wrote:
On 6/10/2010 10:29 AM, Aref wrote:Thank you for the response. However, that
is not the problem. If I do update =
table.update(project.c.ProjectID=='project-name', values =
{project.c.ProjectID:'program'}) print update update.execute() everything
works fine. if I do this: test = 'table.c.'+columns[0] #columns is a list
which contains the columns names update = table.update(test ==
'project-name', values={test:'program'}) update.execute() it does not work. I
get an error that there is no such column. I need to be able to update
columns dynamically where I do not have a prior knowledge of what tables and
what are the table columns that may exist. How can I do that if at all?
Instead try:update = table.update(eval(test)=='project-name',
values={test:'program'})I can't say for sure that's the best way to do it
still, but it would solve your immediate problem. The test variable is
referencing a string, not a column. You have to eval() it to get the column
reference.
However, you say your error is that there is no such column ... I'd expect
a much different error if my suggestion were to actually fix your problem.
Anyway good luck. :) Might include your traceback next time if you still
have problems.
Lance
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Re: [sqlalchemy] mssql 2000 Date type on sa 0.6 maps to non-existant DATE type
2010/6/9 Clovis Fabricio nos...@gmail.com: 2010/6/9 Michael Bayer mike...@zzzcomputing.com: I think I know what the problem is. You need to use freetds version 7.0 or 8.0. If I set mine down to 4.2, I get your goofy results. I'm away from the server right now, I'll do more tests tomorrow, and send you the results. ok, I did some testing and setting tds version to 8.0 fixed it. As a side issue, I had tds version = 8.0 on my freetds.conf file, but that is just not being read. When I use either the connection string or the environment variable to set the tds version, it works. I'll join freetds mailing list to check on this. I'm willing to open tickets and test more results, I'd love to see this solved for good. Any suggestions on the next step? -- nosklo -- You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalch...@googlegroups.com. To unsubscribe from this group, send email to sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en.
Re: [sqlalchemy] Re: help please
On 6/10/2010 11:22 AM, Aref wrote: Thank you very much. I'll try it. Is there a better way of doing this-- I mean there must be since this is necessary for any application needing to modify a database where generally tables are accessed dynamically. Well, I suspect the "better way" would be to follow King Simon's advice (http://groups.google.com/group/sqlalchemy/msg/b8c0f6bce263ff3d?hl=en) and avoid the eval() stuff as well. Instead you'd be using getattr() or accessing the table.c collection dictionary-style. Lance -- You received this message because you are subscribed to the Google Groups "sqlalchemy" group. To post to this group, send email to sqlalch...@googlegroups.com. To unsubscribe from this group, send email to sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en.
[sqlalchemy] Re: Questions about session
The pprintout was:
{type 'collections.defaultdict': 156,
type 'bool': 2,
type 'float': 1,
type 'int': 538,
type 'list': 1130,
type 'dict': 867,
type 'NoneType': 1,
type 'set': 932,
type 'str': 577,
type 'tuple': 1717,
type 'type': 5,
class 'sqlalchemy.util.symbol': 1,
class 'sqlalchemy.orm.state.InstanceState': 236,
class 'ProjectParties.Student': 156,
class 'ProjectParties.Supervisor': 39,
class 'ProjectParties.Project': 197}
I think the InstanceStates come from the Supervisor and Project
classes (197+39 = 236)
Sounds pretty ugly. What if you add extra tables to represent runs
and/or trials?
class Run(Base):
# Having a separate table here gives you nice auto-incrementing run ids
# and lets you attach additional information to a run, such as timestamp,
# human-supplied comment, etc.
__tablename__ = 'run'
id = Column(Integer, primary_key=True)
timestamp = Column(DateTime, nullable=False)
# comment = Column(UnicodeText(100), nullable=False)
trials = relationship('Trial',
back_populates='run',
order_by=lambda: Trial.id.asc())
class Trial(Base):
# Having a separate table here is of dubious value, but hey it makes the
# relationships a bit nicer!
__tablename__ = 'trial'
__table_args__ = (PrimaryKeyConstraint('run_id', 'id'), {})
run_id = Column(Integer, ForeignKey('run.id'))
id = Column(Integer)
run = relationship('Run', back_populates='trials')
sim_allocs = relationship('SimAllocation', back_populates='trial')
class SimAllocation(Base):
...
__table_args__ = (PrimaryKeyConstraint('run_id', 'trial_id', 'stud_id'),
ForeignKeyConstraint(['run_id', 'trial_id'],
['trial.run_id', 'trial.id']),
{})
run_id = Column(Integer)
trial_id = Column(Integer)
stud_id = Column(Integer)
trial = relationship('Trial', back_populates='sim_allocs')
Ah true, my solution was rather hacky and not very elegant.
Your class definitions... are you defining both table and Class in one
go? Would I have to change the way my monteCarloBasic creates
instances of SimAllocation?
On Jun 9, 9:46 pm, Conor conor.edward.da...@gmail.com wrote:
On 06/09/2010 02:45 PM, Az wrote:
Expected: students, supervisors, projects, dictionaries of said objects,
and other attribute values (strings, ints, lists, etc.). Unexpected:
anything else, especially sessions, InstanceState objects, or other ORM
support objects.
Actually got some stuff like the following (copy-pasting bits from my
print output):
(class 'sqlalchemy.orm.state.InstanceState',)
{'_sa_instance_state': sqlalchemy.orm.state.InstanceState object at
0x2d5beb0, 'proj_id': 1100034, 'postsim_probs': [], 'proj_sup': 1291,
'presim_pop': 0, 'own_project': False, 'allocated': False,
'proj_name': 'MPC on a Chip', 'blocked': False}
Stuff like that :S
I'm not sure what that printout indicates. Try this as your debug printout:
def get_memo_type_count(memo):
retval = {}
for obj in memo.itervalues():
type_ = obj.__class__
retval[type_] = retval.get(type_, 0) + 1
return retval
[perform deep copies]
type_count = get_memo_type_count(memo)
import pprint
pprint.pprint(type_count)
This will tell you, e.g. how may Student objects were copied, how many
InstanceState objects were copied, etc. Remember that you will have to
override __deepcopy__ on your mapped classes or use the
use-case-specific copy function to prevent ORM attributes (such as
_sa_instance_state) from being copied.
[...]
The most likely cause is if you call session.add(temp_alloc) after
calling session.merge(temp_alloc) for the same temp_alloc object. I
noticed your original monteCarloBasic had two calls to
session.add(temp_alloc); did both get changed to
session.merge(temp_alloc)? If that doesn't work, can you verify that
SQLAlchemy's primary key for SimAllocation matches the database's
primary key for sim_alloc? What column type are you using for uid? Which
call to session.merge is failing (line 163 according to your traceback),
the one inside your for rank in ranks loop or the one outside?
Oh yeah good point, they're separate calls. Basically for the one in
for rank in ranks
adds for a student getting a project, the other adds if a student
doesn't get a project since we want
to track all students (allocated or not, since the state of being
unallocated is what gives
us motivation to optimise the results).
Your original monteCarloBasic definition had this:
for rank in ranks:
proj = random.choice(list(student.preferences[rank]))
if not (proj.allocated or proj.blocked or proj.own_project):
[...]
session.add(temp_alloc) # #1
break
ident += 1
session.add(temp_alloc) # #2
session.add #1 is redundant since #2 gets
[sqlalchemy] Re: connection lost contact error for first database connection every morning
Thank you, we will try recycling every hour and see if tomorrow connects without a hitch. On Jun 9, 5:43 pm, Michael Bayer mike...@zzzcomputing.com wrote: since nobody is getting back to you on this one you want to look into pool_recycle athttp://www.sqlalchemy.org/docs/reference/sqlalchemy/connections.html# On Jun 9, 2010, at 10:33 AM, Kerrb wrote: We are using SQLAlchemy with our Plone CMS to connect to an Oracle database. The connection pool is set to 5 and it works fine all day. The first person to try to use it in the morning gets a connection lost contact error. If they refresh they get the connection. Oracle is not dropping the connections - they show up in Oracle as inactive. Is there a switch we're missing when we set up the connection pool in SQLAlchemy? -- You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalch...@googlegroups.com. To unsubscribe from this group, send email to sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group athttp://groups.google.com/group/sqlalchemy?hl=en.- Hide quoted text - - Show quoted text - -- You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalch...@googlegroups.com. To unsubscribe from this group, send email to sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en.
[sqlalchemy] Re: Questions about session
So I laid them out like this:
class Run(Base):
# For autoincrementing run IDs
# Allows addition of more information to a run
__tablename__ = 'run'
id = Column(Integer, primary_key=True)
timestamp = Column(DateTime, nullable=False)
# comment = Column(UnicodeText(100), nullable=False)
trials = relationship('Trial',
back_populates='run',
order_by=lambda: Trial.id.asc())
class Trial(Base):
# Having a separate table here is of dubious value, but hey it
makes the
# relationships a bit nicer!
__tablename__ = 'trial'
__table_args__ = (PrimaryKeyConstraint('run_id', 'id'), {})
run_id = Column(Integer, ForeignKey('run.id'))
id = Column(Integer)
run = relationship('Run', back_populates='trials')
sim_allocs = relationship('SimAllocation', back_populates='trial')
class SimAllocation(Base):
#
__tablename__ = 'sim_alloc'
__table_args__ = (PrimaryKeyConstraint('run_id', 'trial_id',
'stud_id'),
ForeignKeyConstraint(['run_id', 'trial_id'],
['trial.run_id',
'trial.id']),
{})
run_id = Column(Integer)
trial_id = Column(Integer)
stud_id = Column(Integer)
trial = relationship('Trial', back_populates='sim_allocs')
def __init__(self, ident, uid, session_id, stud_id, alloc_proj_rank):
self.ident = ident
self.uid = uid
self.session_id = session_id
self.stud_id = stud_id
self.alloc_proj = None
self.alloc_proj_ref = None
self.alloc_proj_rank = alloc_proj_rank
def __repr__(self):
return str(self)
def __str__(self):
return Row: %s UID: %s - %s: Student: %s (Project: %s - Rank:
%s) %
(self.ident, self.uid, self.session_id, self.stud_id, self.alloc_proj,
self.alloc_proj_rank)
#
The original mapping was:
simulation_allocation = Table('sim_alloc', metadata,
Column('ident', Integer),
Column('uid', String, primary_key=True),
Column('session_id', Integer, primary_key=True),
Column('stud_id', Integer, ForeignKey('studs.ee_id'),
primary_key=True),
Column('alloc_proj', Integer, ForeignKey('projs.proj_id')),
Column('alloc_proj_rank', Integer)
)
mapper(SimAllocation, simulation_allocation, properties={'stud' :
relation(StudentDBRecord), 'proj' : relation(Project)})
Of course, I'd get rid of the project relationship since an
allocated_project and allocated_proj_ref *can* be a NoneType
(realised that right now!)
Additionally, I'd like to maintain the ForeignKey relationship with
the StudentDRRecord table for pulling in info about a student.
Also, I've not got rid of ident because I don't know how else to map
SimAllocation to a dictionary as well. The only thing I could use for
keys was the IDENT before but now that we have a composite key, what
happens to the dictionary? However, the dictionary will just hold
information for the current run really.
On Jun 10, 6:33 pm, Az azfarul.is...@gmail.com wrote:
The pprintout was:
{type 'collections.defaultdict': 156,
type 'bool': 2,
type 'float': 1,
type 'int': 538,
type 'list': 1130,
type 'dict': 867,
type 'NoneType': 1,
type 'set': 932,
type 'str': 577,
type 'tuple': 1717,
type 'type': 5,
class 'sqlalchemy.util.symbol': 1,
class 'sqlalchemy.orm.state.InstanceState': 236,
class 'ProjectParties.Student': 156,
class 'ProjectParties.Supervisor': 39,
class 'ProjectParties.Project': 197}
I think the InstanceStates come from the Supervisor and Project
classes (197+39 = 236)
Sounds pretty ugly. What if you add extra tables to represent runs
and/or trials?
class Run(Base):
# Having a separate table here gives you nice auto-incrementing run ids
# and lets you attach additional information to a run, such as
timestamp,
# human-supplied comment, etc.
__tablename__ = 'run'
id = Column(Integer, primary_key=True)
timestamp = Column(DateTime, nullable=False)
# comment = Column(UnicodeText(100), nullable=False)
trials = relationship('Trial',
back_populates='run',
order_by=lambda: Trial.id.asc())
class Trial(Base):
# Having a separate table here is of dubious value, but hey it makes the
# relationships a bit nicer!
__tablename__ = 'trial'
__table_args__ = (PrimaryKeyConstraint('run_id', 'id'), {})
run_id = Column(Integer, ForeignKey('run.id'))
id = Column(Integer)
run = relationship('Run', back_populates='trials')
sim_allocs = relationship('SimAllocation', back_populates='trial')
class SimAllocation(Base):
...
__table_args__ = (PrimaryKeyConstraint('run_id', 'trial_id', 'stud_id'),
[sqlalchemy] mod_wsgi, SQLite3 and a threading anomaly because connection is not returned to pool by session.remove()
I'm getting the SQLite objects created in a thread can only be used
in that same thread. error when using a web application with mod_wsgi
configured in daemon mode with processes=1, threads=15 on Ubuntu
Karmic, using Python2.6.
I saw another thread [1] which mentioned a similar issue, and I
believe I am using the approach recommended by Mike Bayer in that
thread.
I have a multi-db setup - 2 of the databases are SQLite and one is
PostgreSQL. There are three sessions, set up using
session_var = scoped_session(sessionmaker(extension=extn))
where the extension just allows listeners to be registered which are
called at before_flush and before_commit - I don't believe that's part
of the problem.
When a GET request is received, a user is retrieved from an ID stored
in the HTTP session - this uses a query attribute on the mapped class
which is obtained using session_var.query_property(). All conventional
stuff.
At the end of the request, I call
session_var.remove()
for each of the three sessions. This is what I understand to be the
correct practice - no instantiation of session_var is required.
I enabled debug logging for sqlalchemy.pool and find that under the
failing scenariio, the session_var.remove() sometimes fails to remove
the session. This leads to the SQLite error on a subsequent request.
The failing scenario: Invoke the same URL multiple times from Firefox,
setting a new locale preference (Accept-Language) between requests.
Pretty soon you get the error, full log file is here [2]. I modified
the pool.py code to display a stack trace in the log, so that I could
see what led to a connection being created. From what I can see, it's
the same code path each time.
It's a 219-line trace, but I'll reproduce the relevant lines here: The
PID and thread ID are in braces in each log message.
[ersatz.core:705]{5648/-1385407632} DEBUG dispatching request GET
http://localhost/admin/book/add/
[sqlalchemy.pool.SingletonThreadPool.0x...c44c:275]{5648/-1385407632}
DEBUG Created new connection sqlite3.Connection object at 0x21d61ca0
[sqlalchemy.pool.SingletonThreadPool.0x...c44c:282]{5648/-1385407632}
DEBUG Stack at this point snipped
[sqlalchemy.pool.SingletonThreadPool.0x...c44c:337]{5648/-1385407632}
DEBUG Connection sqlite3.Connection object at 0x21d61ca0 checked out
from pool
[ersatz.core:746]{5648/-1385407632} DEBUG 0.420: time for
http://localhost/admin/book/add/ (end of request processing)
[ersatz.db:328]{5648/-1385407632} DEBUG session cleanup starting
[ersatz.db:336]{5648/-1385407632} DEBUG Calling session.remove() for
db1 (sqlalchemy.orm.scoping.ScopedSession object at 0x21b6190c)
[ersatz.db:336]{5648/-1385407632} DEBUG Calling session.remove() for
db3 (sqlalchemy.orm.scoping.ScopedSession object at 0x21b61aec)
[ersatz.db:336]{5648/-1385407632} DEBUG Calling session.remove() for
db2 (sqlalchemy.orm.scoping.ScopedSession object at 0x21b61ccc)
[sqlalchemy.pool.SingletonThreadPool.0x...c44c:310]{5648/-1385407632}
DEBUG Connection sqlite3.Connection object at 0x21d61ca0 being
returned to pool
[ersatz.db:338]{5648/-1385407632} DEBUG session cleanup done
As can be seen, the session.remove() for the session variable for db2
returns the connection to the pool, as expected. Next request:
[ersatz.core:705]{5648/-1238549648} DEBUG dispatching request GET
http://localhost/admin/book/add/
[sqlalchemy.pool.SingletonThreadPool.0x...c44c:275]{5648/-1238549648}
DEBUG Created new connection sqlite3.Connection object at 0x2202f5a0
[sqlalchemy.pool.SingletonThreadPool.0x...c44c:282]{5648/-1238549648}
DEBUG Stack at this point: snipped
The call to create this connection was made with the same code path as
for the previous request.
[sqlalchemy.pool.SingletonThreadPool.0x...c44c:337]{5648/-1238549648}
DEBUG Connection sqlite3.Connection object at 0x2202f5a0 checked out
from pool
[ersatz.core:746]{5648/-1238549648} DEBUG 0.085: time for
http://localhost/admin/book/add/ (end of request processing)
[ersatz.db:328]{5648/-1238549648} DEBUG session cleanup starting
[ersatz.db:336]{5648/-1238549648} DEBUG Calling session.remove() for
db1 (sqlalchemy.orm.scoping.ScopedSession object at 0x21b6190c)
[ersatz.db:336]{5648/-1238549648} DEBUG Calling session.remove() for
db3 (sqlalchemy.orm.scoping.ScopedSession object at 0x21b61aec)
[ersatz.db:336]{5648/-1238549648} DEBUG Calling session.remove() for
db2 (sqlalchemy.orm.scoping.ScopedSession object at 0x21b61ccc)
[ersatz.db:338]{5648/-1238549648} DEBUG session cleanup done
No connection was returned to the pool! Next request:
[ersatz.core:705]{5648/-1249039504} DEBUG dispatching request GET
http://localhost/admin/book/add/
[sqlalchemy.pool.SingletonThreadPool.0x...c44c:275]{5648/-1249039504}
DEBUG Created new connection sqlite3.Connection object at 0x2202f4a0
[sqlalchemy.pool.SingletonThreadPool.0x...c44c:282]{5648/-1249039504}
DEBUG Stack at this point: snipped
Called from the same place as the previous two requests.
Re: [sqlalchemy] help with 0.6 migration
thats very interesting. Would you care to share with us the error ?
On Jun 10, 2010, at 1:08 PM, Alexander Zhabotinskiy wrote:
I'v get an error with this construction with migrating to 0.6.1
sList = []
if len(curDeps) 0:
for item in curDeps:
sList.append(Orderitem.serivcecomments.like('%:' +
str(item) + '%'))
.
.filter(or_( Orderitem.department_id.in_(curDeps),
(and_((or_(*sList)), Orderitem.isbtype==True)) )) \
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[sqlalchemy] Re: Questions about session
Let me take a guess:
class Supervisor(object):
def __init__(self, ee_id, name, original_quota, loading_limit):
self.ee_id = ee_id
self.name = name
self.original_quota = original_quota
self.loading_limit = loading_limit
self.predecr_quota = 0
self.offered_proj = set()
self.total_prealloc_pop = 0
self.total_postalloc_pop = 0
def __repr__(self):
return str(self)
def __str__(self):
return self.name
return %s %s %s (Offered projects: %s) %(self.ee_id,
self.name,
self.predecr_quota, self.offered_proj)
So *inside* the Supervisor class would I define it like this (trying
to have a go at it)?
def __deepcopy__(self, memo):
dc = type(self)()
dc.__dict__.update(self.__dict__)
for attr in dir(supervisor):
if not attr.startswight('__'):
self.attr = deepcopy(self.attr, memo)
So this only overrides __deepcopy__ when I call it for a Supervisor
and not for any of the other classes right?
On Jun 10, 6:56 pm, Az azfarul.is...@gmail.com wrote:
So I laid them out like this:
class Run(Base):
# For autoincrementing run IDs
# Allows addition of more information to a run
__tablename__ = 'run'
id = Column(Integer, primary_key=True)
timestamp = Column(DateTime, nullable=False)
# comment = Column(UnicodeText(100), nullable=False)
trials = relationship('Trial',
back_populates='run',
order_by=lambda: Trial.id.asc())
class Trial(Base):
# Having a separate table here is of dubious value, but hey it
makes the
# relationships a bit nicer!
__tablename__ = 'trial'
__table_args__ = (PrimaryKeyConstraint('run_id', 'id'), {})
run_id = Column(Integer, ForeignKey('run.id'))
id = Column(Integer)
run = relationship('Run', back_populates='trials')
sim_allocs = relationship('SimAllocation', back_populates='trial')
class SimAllocation(Base):
#
__tablename__ = 'sim_alloc'
__table_args__ = (PrimaryKeyConstraint('run_id', 'trial_id',
'stud_id'),
ForeignKeyConstraint(['run_id', 'trial_id'],
['trial.run_id',
'trial.id']),
{})
run_id = Column(Integer)
trial_id = Column(Integer)
stud_id = Column(Integer)
trial = relationship('Trial', back_populates='sim_allocs')
def __init__(self, ident, uid, session_id, stud_id, alloc_proj_rank):
self.ident = ident
self.uid = uid
self.session_id = session_id
self.stud_id = stud_id
self.alloc_proj = None
self.alloc_proj_ref = None
self.alloc_proj_rank = alloc_proj_rank
def __repr__(self):
return str(self)
def __str__(self):
return Row: %s UID: %s - %s: Student: %s (Project: %s -
Rank: %s) %
(self.ident, self.uid, self.session_id, self.stud_id, self.alloc_proj,
self.alloc_proj_rank)
#
The original mapping was:
simulation_allocation = Table('sim_alloc', metadata,
Column('ident', Integer),
Column('uid', String, primary_key=True),
Column('session_id', Integer, primary_key=True),
Column('stud_id', Integer, ForeignKey('studs.ee_id'),
primary_key=True),
Column('alloc_proj', Integer, ForeignKey('projs.proj_id')),
Column('alloc_proj_rank', Integer)
)
mapper(SimAllocation, simulation_allocation, properties={'stud' :
relation(StudentDBRecord), 'proj' : relation(Project)})
Of course, I'd get rid of the project relationship since an
allocated_project and allocated_proj_ref *can* be a NoneType
(realised that right now!)
Additionally, I'd like to maintain the ForeignKey relationship with
the StudentDRRecord table for pulling in info about a student.
Also, I've not got rid of ident because I don't know how else to map
SimAllocation to a dictionary as well. The only thing I could use for
keys was the IDENT before but now that we have a composite key, what
happens to the dictionary? However, the dictionary will just hold
information for the current run really.
On Jun 10, 6:33 pm, Az azfarul.is...@gmail.com wrote:
The pprintout was:
{type 'collections.defaultdict': 156,
type 'bool': 2,
type 'float': 1,
type 'int': 538,
type 'list': 1130,
type 'dict': 867,
type 'NoneType': 1,
type 'set': 932,
type 'str': 577,
type 'tuple': 1717,
type 'type': 5,
class 'sqlalchemy.util.symbol': 1,
class 'sqlalchemy.orm.state.InstanceState': 236,
class 'ProjectParties.Student': 156,
class 'ProjectParties.Supervisor': 39,
class 'ProjectParties.Project': 197}
I think the InstanceStates come from the Supervisor and
Re: [sqlalchemy] mod_wsgi, SQLite3 and a threading anomaly because connection is not returned to pool by session.remove()
On Jun 10, 2010, at 2:54 PM, Vinay Sajip wrote: I'm getting the SQLite objects created in a thread can only be used in that same thread. error when using a web application with mod_wsgi configured in daemon mode with processes=1, threads=15 on Ubuntu Karmic, using Python2.6. When a GET request is received, a user is retrieved from an ID stored in the HTTP session - this uses a query attribute on the mapped class which is obtained using session_var.query_property(). All conventional stuff. First off, the absolute recommended behavior for SQLite if a file-based database is to not use pooling. I would suggest you use a NullPool to eliminate any connection pooling. Some detail on this at http://www.sqlalchemy.org/docs/reference/dialects/sqlite.html#threading-behavior . Seems like I mention it in the linked thread as well. You then need to ensure no sqlalchemy-session-bound objects in your web application are shared between threads. When you put things into your HTTP session, assuming its an in-memory HTTP session, make sure objects that go in there arent attached to a SQLAlchemy session. Use expunge() or similar for this. Calling remove() at the end of the request will work, except for the fact that a concurrent thread might be accessing the HTTP session before you get that far.I would recommend using cookie based HTTP sessions in any case (see Beaker for this functionality). Using Mike Bayer's _threading_local patch in thread [1] made no difference. That thread regarded someone using an extremely rare tool called PyISAPIe, which had threading bugs in it. That doesn't apply to a basic mod_wsgi configuration. -- You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalch...@googlegroups.com. To unsubscribe from this group, send email to sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en.
