Re: [Sqlalchemy-tickets] [sqlalchemy] #2944: Confusing error message when passing empty list to Insert.values()

[sqlalchemy <mi...@zz...>]

#2944: Confusing error message when passing empty list to Insert.values()
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      Reporter:  jet57            |      Owner:  zzzeek
          Type:  defect           |     Status:  new
      Priority:  medium           |  Milestone:
     Component:  (none)           |   Severity:  no triage selected yet
    Resolution:                   |   Keywords:
Progress State:  awaiting triage  |
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Comment (by zzzeek):

 an empty list should indicate a single list of parameters for one row,
 where the row has no values.

 so this patch:

 {{{
 #!diff
 diff --git a/lib/sqlalchemy/sql/dml.py b/lib/sqlalchemy/sql/dml.py
 index 854b894..658b116 100644
 --- a/lib/sqlalchemy/sql/dml.py
 +++ b/lib/sqlalchemy/sql/dml.py
 @@ -37,7 +37,8 @@ class UpdateBase(DialectKWArgs, HasPrefixes, Executable,
 ClauseElement):
                  return p

          if isinstance(parameters, (list, tuple)) and \
 -              isinstance(parameters[0], (list, tuple, dict)):
 +            parameters and \
 +            isinstance(parameters[0], (list, tuple, dict)):

              if not self._supports_multi_parameters:
                  raise exc.InvalidRequestError(
 }}}

 gets us this for PG:

 {{{
 from sqlalchemy.sql import table, column
 from sqlalchemy.dialects import postgresql

 s = table('t', column('a'), column('b')).insert().values([])
 print s.compile(dialect=postgresql.dialect())}

 INSERT INTO t DEFAULT VALUES
 }}}

 the same as if you called `.values()` with no argument.

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Ticket URL: <http://www.sqlalchemy.org/trac/ticket/2944#comment:1>
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