sqlobject-discuss

[SQLObject] Checking if a table exists ?

[Markus J. <mar...@ya...>]

hello

what is the best way in SQLObject to check if
a table already exists.

lets say I have a table of authors and a 
class Author.

for creating the table I would call
Author.createTable()

now I want to check everytime I start my programm
if the table already exists and if not it should
be created.

is there a way to this ?

I could't find anything in the documentation.

thanks

regards

Markus








	

	
		
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Re: [SQLObject] Checking if a table exists ?

[<pa...@su...>]

Markus Jais wrote:
> hello
> 
> what is the best way in SQLObject to check if
> a table already exists.
> 
> lets say I have a table of authors and a 
> class Author.
> 
> for creating the table I would call
> Author.createTable()
> 
> now I want to check everytime I start my programm
> if the table already exists and if not it should
> be created.
Author.createTable(ifNotExists=True)

hth
  Paul

[SQLObject] Re: Checking if a table exists ?

[Hendrik M. <he...@ma...>]

> Author.createTable(ifNotExists=True)

IMO, it would still be very handy to be able to have SQLObject check if a
table exists. In fact, I think it would be very cool if SQLObject provided
a method that compares an existing database table scheme to the scheme
defined in an SQLObject class and returns True if they match.

- Hendrik

-- 
http://www.mans.de

Re: [SQLObject] Checking if a table exists ?

[Ian B. <ia...@co...>]

paul kölle wrote:
>> now I want to check everytime I start my programm
>> if the table already exists and if not it should
>> be created.
> 
> Author.createTable(ifNotExists=True)

Besides this you can also do __connection__.tableExists('author').  And 
you could try something like:

if __connection__.tableExists('author'):
     class DBAuthor(SQLObject):
         _table = 'author'
         _fromDatabase = True

And then you could compare DBAuthor._columns with Author._columns, to 
make sure the schema was up-to-date.  From there you might just signal 
an error if not, or you could try to do something more sophisticated. 
But be warned that this introspection is getting into undocumented 
portions of SQLObject, that might change in the future.

-- 
Ian Bicking  /  ia...@co...  / http://blog.ianbicking.org

Re: [SQLObject] Checking if a table exists ?

[Markus J. <mar...@ya...>]

thanks.this is what I was looking for.

regards

markus

 --- Ian Bicking <ia...@co...> schrieb: 
> paul kölle wrote:
> >> now I want to check everytime I start my programm
> >> if the table already exists and if not it should
> >> be created.
> > 
> > Author.createTable(ifNotExists=True)
> 
> Besides this you can also do
> __connection__.tableExists('author').  And 
> you could try something like:
> 
> if __connection__.tableExists('author'):
>      class DBAuthor(SQLObject):
>          _table = 'author'
>          _fromDatabase = True
> 
> And then you could compare DBAuthor._columns with
> Author._columns, to 
> make sure the schema was up-to-date.  From there you
> might just signal 
> an error if not, or you could try to do something
> more sophisticated. 
> But be warned that this introspection is getting
> into undocumented 
> portions of SQLObject, that might change in the
> future.
> 
> -- 
> Ian Bicking  /  ia...@co...  /
> http://blog.ianbicking.org
> 
> 
>
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