by-crate-id query bug

[Jonathan Strong]

https://github.com/mcorbin/meuse/blob/master/src/meuse/db/queries/category.clj#L27-L37

this code seems to return all categories, not just the categories associated with the crate.

I think the query needs to have the crate_id condition as part of the where clause, not as part of the left-join.

exapmle:

meuse=# select c.id, c.description, c.name, cc.crate_id
from categories c 
left join crates_categories cc on c.id=cc.category_id and cc.crate_id='2ff956f6-7b3e-49fc-8697-845d3a10fc75';

                  id                  |       description        |           name           |               crate_id               
--------------------------------------+--------------------------+--------------------------+--------------------------------------
 5527b5af-84ec-432f-b4a5-698048e5d096 | statistics               | statistics               | 2ff956f6-7b3e-49fc-8697-845d3a10fc75
 3759e640-2ba1-49c0-9ca3-10babdb07629 | science                  | science                  | 

"science" row should not be part of query results. if you change the second clause of the left-join to be in the where clause instead, it works without returning extra rows:

meuse=# select c.id, c.description, c.name, cc.crate_id
from categories c 
left join crates_categories cc on c.id=cc.category_id 
where cc.crate_id='2ff956f6-7b3e-49fc-8697-845d3a10fc75';

                  id                  |       description        |           name           |               crate_id               
--------------------------------------+--------------------------+--------------------------+--------------------------------------
 5527b5af-84ec-432f-b4a5-698048e5d096 | statistics               | statistics               | 2ff956f6-7b3e-49fc-8697-845d3a10fc75

fwiw I did try to fix this in the clojure code but failed :( - maybe next time.

[Jonathan Strong]

figured it out, just needed to replace left-join with join. will file a PR shortly.

fixed version:

(defn by-crate-id
  [crate-id]
  (-> (h/select :c.id
                :c.name
                :c.description)
      (h/from [:categories :c])
      (h/join [:crates_categories :cc]
                   [:and
                    [:= :cc.category_id :c.id]
                    [:= :cc.crate_id crate-id]])
      sql/format))