[patch] Make new get_values() function more forgiving of mistakes

[rmunn@…]

Thanks for applying my patch from #214! There's one part of it that got omitted, though, and I'm wondering why: it's the part that Does The Right Thing if the user passes a string for the fields=... kwarg. When testing the patch, I found that when I only wanted one field, it was a natural mistake to forget to pass it as a list. I was doing things like "get_values(fields='name', distinct=True" instead of "get_values(fields=['name'], distinct=True". And this was my own code I was calling: if I was making that mistake, others will be also. In the same spirit as [213], I think we should be more forgiving of this mistake: what the user meant is unambiguous, so there's no harm in allowing it.

Here's a patch to implement this idea:

Index: django/core/meta.py
===================================================================
--- django/core/meta.py (revision 359)
+++ django/core/meta.py (working copy)
@@ -1100,6 +1100,10 @@
     except KeyError: # Default to all fields.
         fields = [f.name for f in opts.fields]

+    if isinstance(fields, basestring):
+        # Be forgiving of mistakes: convert to list
+        fields = [fields]
+
     cursor = db.db.cursor()
     _, sql, params = function_get_sql_clause(opts, **kwargs)
     select = ['%s.%s' % (opts.db_table, f) for f in fields]

[Adrian Holovaty]

I talked it over with Jacob, and we agreed strongly that this is too much ​DWIM for our tastes.

[mmarshall]

So, perhaps it still should check if a string was given, and give a friendly error if so?

MWM