can't use RowProxy in params to execute()

[jek]

data = db1.execute(tbl.select())
db2.execute(tbl.insert(), data) # or list(data)

ought to work to copy data from one engine to another. haven't looked at the source yet, but the traceback suggests that execute *params inspection is doing an isinstance(dict) where it could be duck-typing hasattr('keys')

current workaround:

db2.execute(tbl.insert(), [for row in data](dict(row.items())))

[Mike Bayer]

someone hit this the other day, so lets do it.

[Mike Bayer]

after some research, I think the full feature here is not possible without making some expensive across-the-board behavior. The resultproxy is an iterator, and peeking into it requires that it be a non-iterable. This would imply we have to convert all incoming arguments into lists/tuples/dicts in all cases just to inspect them, which 99% of the time is needless overhead.

This fragment doesn't entirely work, but this is the idea:

Index: lib/sqlalchemy/engine/base.py
===================================================================
--- lib/sqlalchemy/engine/base.py   (revision 5546)
+++ lib/sqlalchemy/engine/base.py   (working copy)
@@ -834,17 +834,17 @@
                 return [        elif len(multiparams) == 1:
             zero = multiparams[0](]
)
-            if isinstance(zero, (list, tuple)):
-                if not zero or isinstance(zero[0](0), (list, tuple, dict)):
-                    return zero
+            if hasattr(zero, 'iteritems'):
+                return [zero](zero)
+            elif hasattr(zero, '__iter__'):
+                if not zero or hasattr(zero[0](0), '__iter__'):
+                    return tuple(zero)
                 else:
                     return [zero](zero)
-            elif isinstance(zero, dict):
-                return [zero](zero)
             else:
                 return [[zero]([zero)]
         else:
-            if isinstance(multiparams[0](0), (list, tuple, dict)):
+            if hasattr(multiparams[0](0), '__iter__'):
                 return multiparams
             else:
                 return [multiparams](multiparams)

a not-yet-working patch is attached.

Right now I think if you have a ResultProxy, you've got a live cursor. If you want to use an iterable as an argument, you should be explicit in converting it to a stable datastructure before passing it - SQLA shouldn't do that job.

[Mike Bayer]

yeah, list(data) works, never mind the noise. 7009653aa1c53d1f761501522d55617d3fdcc57c

[Mike Bayer]

Removing milestone: 0.5.0 (automated comment)