On May 24, 11:50 pm, Larry Martell <larry.mart...@gmail.com> wrote:
> I got this to work by adding the derived field to the drill down query
> with queryset.extra, and then it was available with getattr. The only
> issue I had was they wanted the derived field displayed with a name
> (not col1-col2). In the first query I was able to easily do this. But
> in the drill down query I had to do:
>
> extra(select={self.field_name : self.field_name})
The QuerySet.extra() "select" params is a mapping of
"attribute_name":"SQL clause", so you could just write:
extra(select={"Delta" : "col1 - col2"})
of for somethin more generic:
extra(select={self.display_name: self.sql_clause})
or if more than one extra field involved:
extra(select=self.extra_fields)
where extra_fields = {"displayname1":"sql clause 1", "displayname2",
"sql clause 2"}
> I couldn't use the display name or the getattr failed.
???
> But then it was
> displaying with 'col1-col2'. So then I had to explicitly test for it
> and set the display name:
>
> if field_name == 'col1-col2': display_name = 'Delta'
> else: display_name = field_name
If you need display names that you don't want to use as field names
(or if you want translatable display names etc), you can maintain a
mapping of fieldname:display_name and then just do a dict lookup, ie:
display_name = display_names.get(field_name, field_name)
Can't really help more here without seeing the actual code, but from
years of experience with Python, I really doubt you have to write
something as ugly as the above snippet ;)
HTH
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