> -----Original Message-----
> From: sqlalchemy@googlegroups.com
> [mailto:sqlalch...@googlegroups.com] On Behalf Of Harry Percival
> Sent: 03 June 2010 16:24
> To: sqlalchemy@googlegroups.com
> Subject: [sqlalchemy] reflecting existing databases with no a
> priori knowledge of their structure
>
> Hi All,
>
> I'm building a tool to extract info from databases. The
> user/programmer doesn't have any advance knowledge of the structure of
> the database before they load it, and i want to dynamically generate
> mapped classes for the database.
>
> i just want to check there isn't some helpful sqlalchemy stuff that
> can make my life easier, cos it feels harder than it should be.
>
> sqlsoup seems to expect you to know table names ahead of time. i can't
> find a way of extracting a list of table names from db =
> SqlSoup(engine) and i'm finding myself generating classes on the fly
> using the type() function.
>
> stuff like:
>
>
>
> meta.reflect(bind=engine)
> tables = meta.raw_tables
>
> class MyTable(object):
> pass
>
> for t in tables:
> tempclass =
> type('Table%d'%counter,(MyTable,),{'engine':self.engine})
> mapper(tempclass,t)
>
> then i use a bunch of classfunctions hanging off MyTable to do things
> like return select alls ... anyways, this feels harder than it should
> be. am i missing something? or is sqlalchemy simply not really used
> much to work with existing / arbitrary databases?
>
I'm not quite sure what you're asking for. Once you've used meta.reflect to
reflect all your tables, you can pass that metadata instance to the SqlSoup
constructor. So you now have all the table names available in MetaData.tables
(or MetaData.sorted_tables), and you can access the mapped classes via
SqlSoup.entity(<table_name>).
For example:
import sqlalchemy as sa
from sqlalchemy.ext.sqlsoup import SqlSoup
meta = sa.MetaData('db://user:passw...@host/database')
meta.reflect()
db = SqlSoup(meta)
for table in meta.sorted_tables:
cls = db.entity(table.name)
print cls
print cls.get(1)
Hope that helps,
Simon
Hope that helps,
Simon
--
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.
