Rails - Nov 2009 - new column in ActiveRecord object, method_missing() called intermittently

Hi,

I''m using the geokit plugin to provide a
"find-locations-on-radius"
feature in my app. When a location is added to the database, the
actual address is translated (geocoded) into a longitude & latitude.
The longitude and the latitude are stored in the database. When a user
performs a "find-locations-on-a-X-miles-radius" from a point of origin
(an address), a distance is calculated from the given point of origin
to all the stored locations. Geokit overrides the ActiveRecord find
method to include a distance column:

[:all, {:select=>"*,                   SQRT(POW(XXX*(XXX-
locations.lat),2)+\n                  POW(XXX*(XXX-locations.lng),2))
\n AS distance", :order=>"distance asc"}]

Then from any view you can access the distance on the objects
retrieved by find:

Location.find(:all,:origin =>[@ip_location.lat,
@ip_location.lng]).each { |location|
  location.distance
}

The problem that I have is that location.distance returns empty/nil
once in a while. From what I understand, when location.distance is
called, it invokes method_missing() in activerecord/lib/active_record/
attribute_methods.rb. That is because there is no distance column in
the locations table, so it goes to the object''s attributes to find the
distance. Well, it just so happens that once in a while method_missing
() is not invoked when accessing location.distance. I put tracing in
method_missing() and when I get distance values method_missing was
indeed called, and when I get blank/nil - method_missing was not
called.

I thought it was because of caching, but I turned off caching in
production, and I don''t have any explicit caching logic in my views or
in my controllers.

I asked this question on the geokit group but nobody answered it:
http://groups.google.com/group/geokit/browse_thread/thread/ce364a46d802d399
. You can see all debugging and tracing here.

Why doesn''t method_missing get invoked all the time when
location.distance is called? What gets invoked then? Could this be
some sort of caching bug?

Thanks,
Jenna

On Nov 6, 7:34 am, jenna_s
<jenna.sim...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
> Why doesn''t method_missing get invoked all the time when
> location.distance is called? What gets invoked then? Could this be
> some sort of caching bug?
So the times that it returns nil, what does get called ? have you
tried stepping through it with the debugger ?

Fred
>
> Thanks,
> Jenna

On Nov 6, 2:34 am, jenna_s
<jenna.sim...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:
> Why doesn''t method_missing get invoked all the time when
> location.distance is called? What gets invoked then? Could this be
> some sort of caching bug?
>
The other issue I''ve seen with things like this was that some find
options (:include, notably) will drop the :select clause, meaning that
you won''t get an attribute back for distance. Any chance that could be
involved?

--Matt Jones

It returns nil when you use joins or includes on your finds. Try
records.sort_by_distance_from origin. That will add the distance
column back

2009/11/6, jenna_s
<jenna.simmer-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>:
>
> Hi,
>
> I''m using the geokit plugin to provide a
"find-locations-on-radius"
> feature in my app. When a location is added to the database, the
> actual address is translated (geocoded) into a longitude & latitude.
> The longitude and the latitude are stored in the database. When a user
> performs a "find-locations-on-a-X-miles-radius" from a point of
origin
> (an address), a distance is calculated from the given point of origin
> to all the stored locations. Geokit overrides the ActiveRecord find
> method to include a distance column:
>
> [:all, {:select=>"*,                   SQRT(POW(XXX*(XXX-
> locations.lat),2)+\n                  POW(XXX*(XXX-locations.lng),2))
> \n AS distance", :order=>"distance asc"}]
>
> Then from any view you can access the distance on the objects
> retrieved by find:
>
> Location.find(:all,:origin =>[@ip_location.lat,
> @ip_location.lng]).each { |location|
>   location.distance
> }
>
> The problem that I have is that location.distance returns empty/nil
> once in a while. From what I understand, when location.distance is
> called, it invokes method_missing() in activerecord/lib/active_record/
> attribute_methods.rb. That is because there is no distance column in
> the locations table, so it goes to the object''s attributes to find
the
> distance. Well, it just so happens that once in a while method_missing
> () is not invoked when accessing location.distance. I put tracing in
> method_missing() and when I get distance values method_missing was
> indeed called, and when I get blank/nil - method_missing was not
> called.
>
> I thought it was because of caching, but I turned off caching in
> production, and I don''t have any explicit caching logic in my
views or
> in my controllers.
>
> I asked this question on the geokit group but nobody answered it:
> http://groups.google.com/group/geokit/browse_thread/thread/ce364a46d802d399
> . You can see all debugging and tracing here.
>
> Why doesn''t method_missing get invoked all the time when
> location.distance is called? What gets invoked then? Could this be
> some sort of caching bug?
>
> Thanks,
> Jenna
>
> >
>
-- 
Von meinen Mobilgerät aus gesendet

I''ll try that. It''s just that it is hard to make it repeatable
for
debugging.

On Nov 6, 12:25 am, Frederick Cheung
<frederick.che...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:
> On Nov 6, 7:34 am, jenna_s
<jenna.sim...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
>
> > Why doesn''t method_missing get invoked all the time when
> > location.distance is called? What gets invoked then? Could this be
> > some sort of caching bug?
>
> So the times that it returns nil, what does get called ? have you
> tried stepping through it with the debugger ?
>
> Fred
>
>
>
> > Thanks,
> > Jenna

I did read that in the geokit README, but I have no include in my
statement.

On Nov 6, 2:13 pm, Matt Jones
<al2o...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:
> On Nov 6, 2:34 am, jenna_s
<jenna.sim...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
>
> > Why doesn''t method_missing get invoked all the time when
> > location.distance is called? What gets invoked then? Could this be
> > some sort of caching bug?
>
> The other issue I''ve seen with things like this was that some find
> options (:include, notably) will drop the :select clause, meaning that
> you won''t get an attribute back for distance. Any chance that
could be
> involved?
>
> --Matt Jones

I''ll try it. Thanks.
Jenna

On Nov 7, 9:14 am, mike <mikez...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:
> It returns nil when you use joins or includes on your finds. Try
> records.sort_by_distance_from origin. That will add the distance
> column back
>
> 2009/11/6, jenna_s
<jenna.sim...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>:
>
>
>
>
>
> > Hi,
>
> > I''m using thegeokitplugin to provide a
"find-locations-on-radius"
> > feature in my app. When a location is added to the database, the
> > actual address is translated (geocoded) into a longitude &
latitude.
> > The longitude and the latitude are stored in the database. When a user
> > performs a "find-locations-on-a-X-miles-radius" from a point
of origin
> > (an address), a distance is calculated from the given point of origin
> > to all the stored locations.Geokitoverrides the ActiveRecord find
> > method to include a distance column:
>
> > [:all, {:select=>"*,                   SQRT(POW(XXX*(XXX-
> > locations.lat),2)+\n                  POW(XXX*(XXX-locations.lng),2))
> > \n AS distance", :order=>"distance asc"}]
>
> > Then from any view you can access the distance on the objects
> > retrieved by find:
>
> > Location.find(:all,:origin =>[@ip_location.lat,
> > @ip_location.lng]).each { |location|
> >   location.distance
> > }
>
> > The problem that I have is that location.distance returns empty/nil
> > once in a while. From what I understand, when location.distance is
> > called, it invokes method_missing() in activerecord/lib/active_record/
> > attribute_methods.rb. That is because there is no distance column in
> > the locations table, so it goes to the object''s attributes to
find the
> > distance. Well, it just so happens that once in a while method_missing
> > () is not invoked when accessing location.distance. I put tracing in
> > method_missing() and when I get distance values method_missing was
> > indeed called, and when I get blank/nil - method_missing was not
> > called.
>
> > I thought it was because of caching, but I turned off caching in
> > production, and I don''t have any explicit caching logic in my
views or
> > in my controllers.
>
> > I asked this question on thegeokitgroup but nobody answered it:
>
>http://groups.google.com/group/geokit/browse_thread/thread/ce364a46d8...
> > . You can see all debugging and tracing here.
>
> > Why doesn''t method_missing get invoked all the time when
> > location.distance is called? What gets invoked then? Could this be
> > some sort of caching bug?
>
> > Thanks,
> > Jenna
>
> --
> Von meinen Mobilgerät aus gesendet

jenna_s wrote:
> I''ll try it. Thanks.
> Jenna
Please quote when you reply -- otherwise it''s impossible to know what 
you''re replying to.

Best,
--
Marnen Laibow-Koser
http://www.marnen.org
marnen-sbuyVjPbboAdnm+yROfE0A@public.gmane.org
-- 
Posted via http://www.ruby-forum.com/.

Hi Mike,

I tried your suggestion (putting sort_by_distance_from right after the
find()) and it seems to work. I don''t understand why, because I really
don''t have an :include in the find(). I''m just disappointed
with
myself because I thought I can debug any Rails problem, and this one
showed me that I can''t.

Thanks,
J

On Nov 7, 9:14 am, mike <mikez...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:
> It returns nil when you use joins or includes on your finds. Try
> records.sort_by_distance_from origin. That will add the distance
> column back
>
> 2009/11/6, jenna_s
<jenna.sim...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>:
>
>
>
>
>
> > Hi,
>
> > I''m using thegeokitplugin to provide a
"find-locations-on-radius"
> > feature in my app. When a location is added to the database, the
> > actual address is translated (geocoded) into a longitude &
latitude.
> > The longitude and the latitude are stored in the database. When a user
> > performs a "find-locations-on-a-X-miles-radius" from a point
of origin
> > (an address), a distance is calculated from the given point of origin
> > to all the stored locations.Geokitoverrides the ActiveRecord find
> > method to include a distance column:
>
> > [:all, {:select=>"*,                   SQRT(POW(XXX*(XXX-
> > locations.lat),2)+\n                  POW(XXX*(XXX-locations.lng),2))
> > \n AS distance", :order=>"distance asc"}]
>
> > Then from any view you can access the distance on the objects
> > retrieved by find:
>
> > Location.find(:all,:origin =>[@ip_location.lat,
> > @ip_location.lng]).each { |location|
> >   location.distance
> > }
>
> > The problem that I have is that location.distance returns empty/nil
> > once in a while. From what I understand, when location.distance is
> > called, it invokes method_missing() in activerecord/lib/active_record/
> > attribute_methods.rb. That is because there is no distance column in
> > the locations table, so it goes to the object''s attributes to
find the
> > distance. Well, it just so happens that once in a while method_missing
> > () is not invoked when accessing location.distance. I put tracing in
> > method_missing() and when I get distance values method_missing was
> > indeed called, and when I get blank/nil - method_missing was not
> > called.
>
> > I thought it was because of caching, but I turned off caching in
> > production, and I don''t have any explicit caching logic in my
views or
> > in my controllers.
>
> > I asked this question on thegeokitgroup but nobody answered it:
>
>http://groups.google.com/group/geokit/browse_thread/thread/ce364a46d8...
> > . You can see all debugging and tracing here.
>
> > Why doesn''t method_missing get invoked all the time when
> > location.distance is called? What gets invoked then? Could this be
> > some sort of caching bug?
>
> > Thanks,
> >Jenna
>
> --
> Von meinen Mobilgerät aus gesendet