ruby - ActiveRecord and might belongs_to -

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i have pair of data types every x may have many y, , each y has @ 1 x.

in database, i'd visualized as

 create table xs (    id integer not null primary key  );  create table ys (    id integer not null primary key,    x_id integer foreign key references xs (id) -- may null  );

using activerecord, it's easy me every x has_many y, how express every y has @ 1 x? impression belongs_to work, i'm not sure how it'll situation when x_id null.

you're right. y should have belongs_to :x.

if x_id not present, y.x return nil.

having belongs_to doesn't mean if value not present, blow up.


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