[sqlalchemy] Longer tuple passed to query.get doesn't throw exception

[Eoghan Murray]

With a class with 3 primary key columns, e.g.

    class MyClass(Entity):
       a = Field(Unicode(64), primary_key=True)
       b = Field(Unicode(64), primary_key=True)
       c = Field(Unicode(64), primary_key=True)
       ...

If you pass 4 values to query.get;

    MyClass.get(('a_val', 'b_val', 'c_val', 'd_val'))

it silently ignores 'd_val' and constructs a query with just a, b and
c columns.
I don't think this behaviour is desirable!  It currently throws an
exception if a 2-tuple is passed to it.

Fix against trunk attached.

In my case I had inadvertently masked the 'd' column:

    class MyClass(Entity):
       a = Field(Unicode(64), primary_key=True)
       b = Field(Unicode(64), primary_key=True)
       c = Field(Unicode(64), primary_key=True)
       d = Field(Unicode(64), primary_key=True)
       ...
       d = Field(Unicode(64))

So that MyClass.table.primary_key.columns only had a, b and c.  Having
the MyClass.get only accepting 3-tuples would have caught this error.
Side issue - this example uses elixir - should elixir have caught the
redeclaration of 'd'?

Cheers!

Eoghan


diff -r 0d9a1a57caac lib/sqlalchemy/orm/query.py
--- a/lib/sqlalchemy/orm/query.py       Thu Nov 18 20:12:24 2010 -0500
+++ b/lib/sqlalchemy/orm/query.py       Fri Nov 19 18:04:59 2010 +0000
@@ -1919,6 +1919,12 @@
             q = self._clone()

         if ident is not None:
+            if len(ident) != len(mapper.primary_key):
+                raise sa_exc.InvalidRequestError(
+                "Incorrect number of values in identifier to
formulate "
+                "primary key for query.get(); primary key columns are
%s" %
+                ','.join("'%s'" % c for c in
mapper.primary_key))
+
             (_get_clause, _get_params) = mapper._get_clause

             # None present in ident - turn those comparisons
@@ -1939,12 +1945,6 @@
                 for id_val, primary_key in zip(ident,
mapper.primary_key)
             ])

-            if len(params) != len(mapper.primary_key):
-                raise sa_exc.InvalidRequestError(
-                "Incorrect number of values in identifier to
formulate "
-                "primary key for query.get(); primary key columns are
%s" %
-                ','.join("'%s'" % c for c in mapper.primary_key))
-
             q._params = params

         if lockmode is not None:

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