1
0
mirror of https://github.com/hasura/graphql-engine.git synced 2024-12-23 15:32:27 +03:00
graphql-engine/server/src-lib/Hasura/Backends/Postgres/Translate/Insert.hs
2022-07-18 09:46:17 +00:00

111 lines
3.5 KiB
Haskell

-- | Postgres Translate Insert
--
-- Translates IR inserts to Postgres-specific SQL INSERT statements.
module Hasura.Backends.Postgres.Translate.Insert
( mkInsertCTE,
toSQLConflict,
insertCheckConstraint,
insertOrUpdateCheckExpr,
)
where
import Hasura.Backends.Postgres.SQL.DML qualified as S
import Hasura.Backends.Postgres.SQL.Types
import Hasura.Backends.Postgres.Translate.BoolExp
import Hasura.Backends.Postgres.Translate.Returning
import Hasura.Prelude
import Hasura.RQL.IR.Insert
import Hasura.RQL.Types.Backend
import Hasura.SQL.Backend
mkInsertCTE ::
Backend ('Postgres pgKind) =>
InsertQueryP1 ('Postgres pgKind) ->
S.TopLevelCTE
mkInsertCTE (InsertQueryP1 tn cols vals conflict (insCheck, updCheck) _ _) =
S.CTEInsert insert
where
tupVals = S.ValuesExp $ map S.TupleExp vals
insert =
S.SQLInsert tn cols tupVals (toSQLConflict tn <$> conflict)
. Just
. S.RetExp
$ [ S.selectStar,
insertOrUpdateCheckExpr
tn
conflict
(toSQLBool insCheck)
(fmap toSQLBool updCheck)
]
toSQLBool = toSQLBoolExp $ S.QualTable tn
toSQLConflict ::
Backend ('Postgres pgKind) =>
QualifiedTable ->
OnConflictClause ('Postgres pgKind) S.SQLExp ->
S.SQLConflict
toSQLConflict tableName = \case
OCCDoNothing ct -> S.DoNothing $ toSQLCT <$> ct
OCCUpdate OnConflictClauseData {..} ->
S.Update
(toSQLCT cp1udConflictTarget)
(S.buildUpsertSetExp cp1udAffectedColumns cp1udValues)
$ Just $ S.WhereFrag $ toSQLBoolExp (S.QualTable tableName) cp1udFilter
where
toSQLCT ct = case ct of
CTColumn pgCols -> S.SQLColumn pgCols
CTConstraint cn -> S.SQLConstraint cn
-- | Annotates the check constraint expression with @boolean@
-- (<check-condition>)::boolean
insertCheckConstraint :: S.BoolExp -> S.SQLExp
insertCheckConstraint boolExp =
S.SETyAnn (S.SEBool boolExp) S.boolTypeAnn
-- | When inserting data, we might need to also enforce the update
-- check condition, because we might fall back to an update via an
-- @ON CONFLICT@ clause.
--
-- We generate something which looks like
--
-- > INSERT INTO
-- > ...
-- > ON CONFLICT DO UPDATE SET
-- > ...
-- > RETURNING
-- > *,
-- > CASE WHEN xmax = 0
-- > THEN {insert_cond}
-- > ELSE {update_cond}
-- > END
-- > AS "check__constraint"
--
-- See @https://stackoverflow.com/q/34762732@ for more information on the use of
-- the @xmax@ system column.
insertOrUpdateCheckExpr ::
QualifiedTable ->
Maybe (OnConflictClause ('Postgres pgKind) S.SQLExp) ->
S.BoolExp ->
Maybe S.BoolExp ->
S.Extractor
insertOrUpdateCheckExpr qt (Just _conflict) insCheck (Just updCheck) =
asCheckErrorExtractor $
S.SECond
( S.BECompare
S.SEQ
(S.SEQIdentifier (S.QIdentifier (S.mkQual qt) (Identifier "xmax")))
(S.SEUnsafe "0")
)
(insertCheckConstraint insCheck)
(insertCheckConstraint updCheck)
insertOrUpdateCheckExpr _ _ insCheck _ =
-- If we won't generate an ON CONFLICT clause, there is no point
-- in testing xmax. In particular, views don't provide the xmax
-- system column, but we don't provide ON CONFLICT for views,
-- even if they are auto-updatable, so we can fortunately avoid
-- having to test the non-existent xmax value.
--
-- Alternatively, if there is no update check constraint, we should
-- use the insert check constraint, for backwards compatibility.
asCheckErrorExtractor $ insertCheckConstraint insCheck