On Nov 13, 2011, at 8:29 PM, Hanss wrote:
> Hello,
>
> I'm trying to get the name of the columns of my tables, writing
>
> columnDb = self.table.__table__.columns._all_cols
>
> self.labels = [col.name for col in columnDb]
>
> ColumnDb is a Set Type... and it usually returns all the columns in
> the same order defined in the table...but not always. Is not possible
> to force the order always in the same way for all the tables?
First off, _all_cols is private. You know this because it starts with an
underscore, and in this case is also only referenced within ColumnCollection
internally and not part of any documentation. Never rely on private
variables, especially when unnecessary. Sets in Python are not ordered.
The columns in a Table can be iterated in the order in which they were added
based on the ".c." collection directly:
self.labels = [col.name for col in table.c]
this is from
http://www.sqlalchemy.org/docs/core/schema.html#accessing-tables-and-columns
When using Declarative, the order ultimately comes from the order in which each
Column object was generated, which drives the order in which Declarative adds
them to the Table which is then what you get when you iterate over Table.c.
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