[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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[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.-
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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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[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] 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.
