Re: join keys redux

Cyrus Harmon wrote:
> 1. CLSQL def-view-class bug - we should fix the def-view-class stuff to 
> allow for specifying lists for home-key and foreign key.

I look a look at tests/test-init.lisp. I do have a test view class
containing the following:

  (employees
    :reader company-employees
    :db-kind :join
    :db-info (:join-class employee
                          :home-key (companyid groupid)
                          :foreign-key (ecompanyid groupid)
                          :set t))))

You might want to look at the tests in the test suite that use that
view class.

> 2. spec'ing values for a join slot - I'm suggesting that in 
> multi-column join, the join value could be specified by a (constant) 
> value rather than a column name. Imagine tables person ( person_id, 
> name ) and pet ( owner_id, animal_type, name ) and I want to make a 
> slot for dogs (I know, there are other ways to do this, but bear with 
> be and imagine that some nut job has thousands of cats and  I just want 
> dogs :-)) I could specify the join as :home-key '(:person-id 'dog) 
> :foreign-key (:owner-id :animal_type) and get what I want.

Yes, I could see how you might have a view class such as DOG-OWNERS
and then you could just say
  (select 'DOG-OWNERS)

But, isn't the much more common idiom something like

(select-animal-type-owners 'dog)

(defun select-animal-type-owners (a-type)
  (select 'pet-owner-person :where [= [animal_type] a-type]))

This way you don't need to create a new view class every time you want
to select for a different animal type.

Kevin