laravel - Manually inject model relation using Eloquent -

how can add model relations array of model?

e.g.

• domain belongsto owner.
• owner hasone domain.
• i have $domain (instance of domain).
• i have $owner (instance of owner).

i want add $domain $owner->relations[] can use $owner->domain later on in code.

the reason doing such in 1 particular controller need partial data set each model use fluent query join performance reasons fill models.

then readability's sake i'd use $owner->domain->id etc

$domain->owner()->associate($owner); gives me $domain->owner option

but can't work out opposite version

$owner->domain()->associate($domain) $owner->domain()->attach($domain) 

both result in following fatal error

call undefined method illuminate\database\query\builder::[attach|associate] ()

nb: don't want save i've loaded data need.

setrelation() should work. sets value in relations array.

$owner->setrelation('domain', $domain);