leftJoin returning Nothing for right hand table (PgRN)

[wduncanfraser]

leftJoins appear to always return Nothing for the right hand table. For example, in this query:

queryById :: FeatureId -> Query Db1 () (PgR FeatureTable, PgRN FV.VersionTable)
queryById fid = proc () -> do
  (a, b) <- leftJoin
    (query FeatureTable) (query FV.VersionTable)
    (\f v -> eq (#id f) (#feature_id v)) -< ()
  restrict -< eq (#id a) (kol . untag $ fid)
  returnA -< (a, b)

Called here:

fetchById
  :: (MonadIO m, MonadThrow m)
  => FeatureId -> Conn' Db1 -> ExceptT QueryError m FeatureReadable
fetchById fid conn =
  runQuery conn (queryById fid) >>= \r -> do
    traceShowM r

A trace if the result shows:

[(HsR {unHsR = RCons (Tagged (Tagged 1)) (RCons (Tagged (Tagged "things")) (RCons (Tagged (Tagged 2017-11-22 02:29:46.473068 UTC)) (RNil)))},Nothing),(HsR {unHsR = RCons (Tagged (Tagged 1)) (RCons (Tagged (Tagged "things")) (RCons (Tagged (Tagged 2017-11-22 02:29:46.473068 UTC)) (RNil)))},Nothing),(HsR {unHsR = RCons (Tagged (Tagged 1)) (RCons (Tagged (Tagged "things")) (RCons (Tagged (Tagged 2017-11-22 02:29:46.473068 UTC)) (RNil)))},Nothing)]

Which corresponds to the 3 results I should be getting from the leftJoin, however the right side is Nothing. I did some digging and turned query logging on and the query being generated is as follows:

SELECT "result1_0_3" as "result1_4",
	        "result1_1_3" as "result2_4",
	        "result1_2_3" as "result3_4",
	        "result2_0_3" as "result4_4",
	        "result2_1_3" as "result5_4",
	        "result2_2_3" as "result6_4",
	        "result2_3_3" as "result7_4",
	        "result2_4_3" as "result8_4",
	        "result2_5_3" as "result9_4",
	        "result2_6_3" as "result10_4",
	        "result2_7_3" as "result11_4",
	        "result2_8_3" as "result12_4"
	 FROM (SELECT *
	       FROM (SELECT *
	             FROM
	            (SELECT "id0_1" as "result1_0_3",
	                     "name1_1" as "result1_1_3",
	                     "created_date2_1" as "result1_2_3",
	                     *
	              FROM (SELECT *
	                    FROM (SELECT "id" as "id0_1",
	                                 "name" as "name1_1",
	                                 "created_date" as "created_date2_1"
	                          FROM "public"."feature" as "T1") as "T1") as "T1") as "T1"
	             LEFT OUTER JOIN
	            (SELECT "feature_id0_2" as "result2_0_3",
	                     "version_number1_2" as "result2_1_3",
	                     "version_status2_2" as "result2_2_3",
	                     "allow_internal_users3_2" as "result2_3_3",
	                     "created_date4_2" as "result2_4_3",
	                     "private_preview_date5_2" as "result2_5_3",
	                     "public_preview_date6_2" as "result2_6_3",
	                     "public_date7_2" as "result2_7_3",
	                     "core_date8_2" as "result2_8_3",
	                     *
	              FROM (SELECT *
	                    FROM (SELECT "feature_id" as "feature_id0_2",
	                                 "version_number" as "version_number1_2",
	                                 "version_status" as "version_status2_2",
	                                 "allow_internal_users" as "allow_internal_users3_2",
	                                 "created_date" as "created_date4_2",
	                                 "private_preview_date" as "private_preview_date5_2",
	                                 "public_preview_date" as "public_preview_date6_2",
	                                 "public_date" as "public_date7_2",
	                                 "core_date" as "core_date8_2"
	                          FROM "public"."feature_version" as "T1") as "T1") as "T1") as "T2"
	             ON
	             ("id0_1") = ("feature_id0_2")) as "T1"
	       WHERE (("result1_0_3") = 1)) as "T1";

Which when run manually returns the expected results:

 result1_4 | result2_4 |           result3_4           | result4_4 | result5_4 | result6_4 | result7_4 |           result8_4           | result9_4 | result10_4 | result11_4 | result12_4 
-----------+-----------+-------------------------------+-----------+-----------+-----------+-----------+-------------------------------+-----------+------------+------------+------------
         1 | things    | 2017-11-22 02:29:46.473068+00 |         1 |         1 |         0 |           | 2017-11-22 21:49:48.955197+00 |           |            |            | 
         1 | things    | 2017-11-22 02:29:46.473068+00 |         1 |         2 |         0 |           | 2017-11-22 22:04:41.536123+00 |           |            |            | 
         1 | things    | 2017-11-22 02:29:46.473068+00 |         1 |         3 |         0 |           | 2017-11-22 22:23:53.527832+00 |           |            |            | 
(3 rows)

Direct queries of the right hand table and innerJoins work without issue.

This looks like it may be related to #37

CC @boj

[wduncanfraser]

For reference, table definitions in SQL and Tisch:

type instance Columns FeatureTable =
  [ 'Column "id"           'WD 'R  PGInt4        FeatureId
  , 'Column "name"         'W  'R  PGText        FeatureName
  , 'Column "created_date" 'WD 'R  PGTimestamptz CreatedDate
  ]

  CREATE TABLE feature (
    id serial PRIMARY KEY,
    name text UNIQUE,
    created_date timestamptz NOT NULL DEFAULT (now() at time zone 'utc')
  );

type instance Columns VersionTable =
  [ 'Column "feature_id"           'W  'R  PGInt4        FeatureId
  , 'Column "version_number"       'W  'R  PGInt4        VersionNumber
  , 'Column "version_status"       'W  'RN VersionStatus VersionStatus
  , 'Column "allow_internal_users" 'W  'RN PGBool        Bool
  , 'Column "created_date"         'WD 'R  PGTimestamptz CreatedDate
  , 'Column "private_preview_date" 'W  'RN PGTimestamptz UTCTime
  , 'Column "public_preview_date"  'W  'RN PGTimestamptz UTCTime
  , 'Column "public_date"          'W  'RN PGTimestamptz UTCTime
  , 'Column "core_date"            'W  'RN PGTimestamptz UTCTime
  ]

  CREATE TABLE feature_version (
    feature_id int REFERENCES feature(id),
    version_number int NOT NULL,
    version_status int, -- This is tied to a haskell enum type
    allow_internal_users boolean,
    created_date timestamptz NOT NULL DEFAULT (now() at time zone 'utc'),
    private_preview_date timestamptz,
    public_preview_date timestamptz,
    public_date timestamptz,
    core_date timestamptz,
    PRIMARY KEY(feature_id, version_number)
  );