Documentation fixes

[LaurentRDC]

This pull request fixes a few documentation issues, which can now be represented on the website. Each commit is linked to an issue identified in #580.

Fixes #580

[LaurentRDC]

I'm requesting some extra eyes on this because it's not clear to me if the implementation of isJust_ was designed this way.

The original generated SQL query is:

SELECT 
  "t0"."email" AS "res0", 
  "t0"."first_name" AS "res1", 
  "t0"."last_name" AS "res2", 
  "t0"."password" AS "res3", 
  SUM(
    (
      CASE WHEN ("t2"."item_quantity") IS NOT NULL THEN "t2"."item_quantity" ELSE ? END
    ) * (
      CASE WHEN ("t3"."price") IS NOT NULL THEN "t3"."price" ELSE ? END
    )
  ) AS "res4" 
FROM 
  "cart_users" AS "t0" 
  LEFT JOIN "orders" AS "t1" ON ("t1"."for_user__email")=("t0"."email") 
  LEFT JOIN "line_items" AS "t2" ON CASE WHEN (
    (
      (
        (
          ("t1"."id") IS NOT NULL
        ) 
        AND (
          ("t1"."date") IS NOT NULL
        )
      ) 
      AND (
        ("t1"."for_user__email") IS NOT NULL
      )
    ) 
    AND (
      ("t1"."ship_to_address__id") IS NOT NULL
    )
  ) 
  AND (
    ("t1"."shipping_info__id") IS NOT NULL
  ) THEN ("t2"."item_in_order__id")=("t1"."id") ELSE ? END 
  LEFT JOIN "products" AS "t3" ON CASE WHEN (
    (
      ("t2"."item_in_order__id") IS NOT NULL
    ) 
    AND (
      ("t2"."item_for_product__id") IS NOT NULL
    )
  ) 
  AND (
    ("t2"."item_quantity") IS NOT NULL
  ) THEN ("t2"."item_for_product__id")=("t3"."id") ELSE ? END 
GROUP BY 
  "t0"."email", 
  "t0"."first_name", 
  "t0"."last_name", 
  "t0"."password" 
ORDER BY 
  SUM(
    (
      CASE WHEN ("t2"."item_quantity") IS NOT NULL THEN "t2"."item_quantity" ELSE ? END
    ) * (
      CASE WHEN ("t3"."price") IS NOT NULL THEN "t3"."price" ELSE ? END
    )
  ) DESC;

whereas with the third commit here, it becomes:

...
  LEFT JOIN "line_items" AS "t2" ON CASE WHEN NOT(
    (
      (
        (
          (
            ("t1"."id") IS NULL
          ) 
          AND (
            ("t1"."date") IS NULL
          )
        ) 
        AND (
          ("t1"."for_user__email") IS NULL
        )
      ) 
      AND (
        ("t1"."ship_to_address__id") IS NULL
      )
    ) 
    AND (
      ("t1"."shipping_info__id") IS NULL
    )
  ) THEN ("t2"."item_in_order__id")=("t1"."id") ELSE ? END
...

[LaurentRDC]

Hmm this is basically the same "fix" as #442.
I'll make a documentation edit to explain why the second query should be used instead of the first one.