Manually inject model relationship with Eloquent

How can I add a model to the relationship array of another model?

eg.

• Domain belongs to the Owner.
• Owner of hasOne Domain.
• I have $ domain (domain instance).
• I have an owner (owner instance).

I want to add $domain

in $owner->relations[]

so that I can just use $owner->domain

later in my code.

The reason for this is that in one particular controller, I only need a partial dataset from each model, so use freely query for a connection to improve performance and then populate the models.

Then, for readability, I would like to use $owner->domain->id

etc.

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

gives me the option $domain->owner

But then I cannot work out the opposite version

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

      

        
        
        
      

    

both result in the following fatal error

Calling undefined method Illuminate \ Database \ Query \ Builder :: [attach | associate] ()

NB: I don't want to save anything as I have already loaded all the data I need.