Find objects without children

Rails
1

Hello all,

I am a newbie and therefore I am currently discovering the delights of
Activerecord. I have a collection of objects, some of which have
children and some of which have not. I am trying to run a find which
will retrieve all parent objects which have children and then return
an array. I know there is some sleek way to achieve this, and not the
cumbersome iterative approach which looks to be looming ahead.

Any help is mucho appreciated…

j

2

[email protected] wrote:

I am a newbie and therefore I am currently discovering the delights of
Activerecord. I have a collection of objects, some of which have
children and some of which have not. I am trying to run a find which
will retrieve all parent objects which have children and then return
an array. I know there is some sleek way to achieve this, and not the
cumbersome iterative approach which looks to be looming ahead.

Parent.find :all, :select => ‘unique parents.*’,
:joins => ‘inner join children on children.parent_id =
parents.id’

–
We develop, watch us RoR, in numbers too big to ignore.

3

Thanks for you reply,

I didn’t need to use a join I just ran the SQL through

Parent.find_by_sql(‘SELECT parents.id, parents.name FROM parents,
children WHERE parents.id = parents.country_id’)

I was hoping to use Active record instead of applying direct SQL but
thems the breaks.

Laters,

j

4

[email protected] wrote:

I didn’t need to use a join I just ran the SQL through

Parent.find_by_sql(‘SELECT parents.id, parents.name FROM parents,
children WHERE parents.id = parents.country_id’)

The comma is just syntactic sugar for an inner join.

–
We develop, watch us RoR, in numbers too big to ignore.