CODEWITHSUNDEEP
ruby-on-railsactiveadmin
jbihan
jbihan

Reputation: 3099

Cannot understand has_one relation

I have some problems understanding the has_one relation.

I have two models Planning and Sport. A Planning is concerned by one Sport and a Sport can be found in many Plannings. So I defined my Planning this way:

class Planning 
    ...  
    has_one :sport
    ...
end

And I didn't add anything in Sport regarding the Planning. In my mind, this would allow me to access planning.sport but I don't mind if I can't find sport.plannings (which makes no sense).

The problem is that when I try to create a new Planning using my ActiveAdmin interface, I have the following error as soon as I try to access the plannings/new page:

undefined method `planning_id' for #<Planning:0x30d8570>

What I understand is that it checks in Sport that a planning_id exists, but my understanding was that there was just a sport_id in the Planning, not the opposite...

What did I do wrong? Do I need to use an intermediary model? Is this jsut linked to ActiveAdmin?

Thanks!

Upvotes: 0

Views: 69

Answers (1)

usha
usha

Reputation: 29349

What you need is 

class Planning 
    ...  
    belongs_to :sport
    ...
end

class Sport

   has_many: plannings
end

You can think of it like, whoever has the foreign key is like the child. So here planning has the foreign key of sport. So it is a child of Sport and it belongs to sport.

Upvotes: 3

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