Mike,
Thanx for your reply. I'll try out the 3rd option. It would still be better
than updating record by record at object level.
Thanx,
Rajesh
On Wednesday, September 28, 2016 at 1:59:38 PM UTC+5:30, Rajesh Rolo wrote:
>
> I'm trying to do a bulk update using core SQLAlchemy to a postgres
> database. bulk_update_mappings does not work (reports StaleDataError). So
> I'm trying to use core functions to do a bulk update. This works fine when
> the update data passed to the values have all the columns in the db but
> fails to work when we update only a certain columns. In my application,
> during periodic syncs between the server and the client only a few of the
> columns will get updated most of the times.
>
> The code snippet I have for update is :
>
> conn = session.connection()
> table = table_dict[table_key].__table__
> stmt=table.update().where(and_(table.c.user_id==bindparam('uid'),
> tbl_pk[table_key]==bindparam('pkey'))).values()
> conn.execute(stmt, update_list)
>
> Since I update multiple tables on every sync, table names and primary keys
> are indexed through an array. For the example below table_dict[table_key]
> would translate to the table 'nwork' and tbl_pk[table_key] would translate
> to 'table.c.nwid' which would be 'nwork.nwid'.
>
> The update_list is a list of records (that need to get updated) as a
> python dictionary. When the record has values for all the columns it works
> fine and when only some of the columns is getting updated it's throwing the
> following error:
>
> StatementError: (sqlalchemy.exc.InvalidRequestError) A value is required
> for bind parameter 'last_sync', in parameter group 1
> [SQL: u'UPDATE nwork SET type=%(type)s, name=%(name)s,
> last_sync=%(last_sync)s,
> update_time=%(update_time)s, status=%(status)s,
> total_contacts=%(total_contacts)s,
> import_type=%(import_type)s, cur_index=%(cur_index)s WHERE
> nwork.user_id = %(uid)s AND nwork.nwid = %(pkey)s']
>
> In this case the error was happening for a record where the column
> 'last_sync' was not getting updated.
>
> What's the way of doing a bulk update where the records may not have all
> the columns (the same set of them) getting updated?
>
>
> I'm running SQLAlchemy 1.0.14.
>
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