Help with a find

Rails
1

I have a simple one to many relation:

class Precinct
has_many :districts
…
end

I would like to find all Precincts that have no districts in a finder.
Is that possible?

I also am using the searchlogic gem (very nice) but even with that I
could not concoct a one liner to do what I want.

Any ideas would be greatly appreciated!

  • PIto
2

On Oct 5, 2:05 pm, Pito S. [email protected] wrote:

I have a simple one to many relation:

class Precinct
has_many :districts
…
end

I would like to find all Precincts that have no districts in a finder.
Is that possible?

You can do that with a left outer join (and then an isnull to filter
for rows with no districts)

Fred

3

Frederick C. wrote:

On Oct 5, 2:05�pm, Pito S. [email protected] wrote:

I have a simple one to many relation:

class Precinct
� has_many :districts
…
end

I would like to find all Precincts that have no districts in a finder.
Is that possible?

You can do that with a left outer join (and then an isnull to filter
for rows with no districts)

Fred

Thanks… I am not sure how to express that as Precinct.find_… can
you say?

– pito

4

Pito S. wrote:
[…]

Thanks… I am not sure how to express that as Precinct.find_… can
you say?

In cases like that, I usually find it helpful to write the SQL first,
then transform it into ActiveRecord find syntax.

– pito

Best,

Marnen Laibow-Koser
http://www.marnen.org
[email protected]