Re: [Rails-core] conditional eager loading

[Corey Haines]

Would merge work? Something like (off the top of my head):

Shift.includes(:schedules).merge(Schedule.occuring_on(Date.today))

where .occuring_on is

def self.occuring_on(day)
where(:occurs_on => day)
end

-Corey

On Thu, Oct 4, 2012 at 3:44 PM, r1git <erwan...@gmail.com> wrote:
> Does anybody know how to fix this issue:
> https://github.com/rails/rails/issues/4677 ?
>
> It seems so basic and yet there is no clean solution like conditional eager
> loading, something like:
>
> Shift.includes(:schedules).where(:schedules => { :occurs_on => Date.today })
>
> Or another solution would be threw a join request like:
>
> SELECT shifts.*,schedules.* from shifts LEFT JOIN schedules ON
> (schedules.shift_id = shifts.id AND schedules.occurs_on = Date.today);
>
> But using this in a Shift.joins("LEFT JOIN schedules ON (schedules.shift_id
> = shifts.id AND schedules.occurs_on = ?", Date.today) fails to return a
> properly filled Shift arrays. And any access to the Shift.schedules launch a
> new SQL request forgeting the occurs_on constraint...
>
> Thanks for any help
>
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[r1git]

Thank you for your suggestion, I tested it and it launches the same SQL request as

Shift.includes(:schedules).where("schedules.occurs_on = '#{Date.today}'")

which fails to return the shifts with no schedules or schedules not matching the condition. Because the where apply on the whole SQL instead of the JOIN condition.