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106 lines
3.3 KiB
Haskell
106 lines
3.3 KiB
Haskell
module Hasura.Backends.Postgres.Translate.Insert
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( mkInsertCTE
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, toSQLConflict
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, insertCheckConstraint
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, insertOrUpdateCheckExpr
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) where
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import Hasura.Prelude
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import qualified Hasura.Backends.Postgres.SQL.DML as S
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import Hasura.Backends.Postgres.SQL.Types
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import Hasura.Backends.Postgres.Translate.BoolExp
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import Hasura.Backends.Postgres.Translate.Returning
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import Hasura.RQL.IR.Insert
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import Hasura.RQL.Types
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mkInsertCTE
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:: Backend ('Postgres pgKind)
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=> InsertQueryP1 ('Postgres pgKind)
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-> S.CTE
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mkInsertCTE (InsertQueryP1 tn cols vals conflict (insCheck, updCheck) _ _) =
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S.CTEInsert insert
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where
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tupVals = S.ValuesExp $ map S.TupleExp vals
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insert =
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S.SQLInsert tn cols tupVals (toSQLConflict tn <$> conflict)
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. Just
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. S.RetExp
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$ [ S.selectStar
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, insertOrUpdateCheckExpr tn conflict
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(toSQLBool insCheck)
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(fmap toSQLBool updCheck)
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]
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toSQLBool = toSQLBoolExp $ S.QualTable tn
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toSQLConflict
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:: Backend ('Postgres pgKind)
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=> QualifiedTable
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-> ConflictClauseP1 ('Postgres pgKind) S.SQLExp
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-> S.SQLConflict
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toSQLConflict tableName = \case
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CP1DoNothing ct -> S.DoNothing $ toSQLCT <$> ct
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CP1Update ct inpCols preSet filtr -> S.Update
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(toSQLCT ct) (S.buildUpsertSetExp inpCols preSet) $
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Just $ S.WhereFrag $ toSQLBoolExp (S.QualTable tableName) filtr
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where
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toSQLCT ct = case ct of
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CTColumn pgCols -> S.SQLColumn pgCols
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CTConstraint cn -> S.SQLConstraint cn
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-- | Annotates the check constraint expression with @boolean@
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-- (<check-condition>)::boolean
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insertCheckConstraint :: S.BoolExp -> S.SQLExp
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insertCheckConstraint boolExp =
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S.SETyAnn (S.SEBool boolExp) S.boolTypeAnn
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-- | When inserting data, we might need to also enforce the update
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-- check condition, because we might fall back to an update via an
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-- @ON CONFLICT@ clause.
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--
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-- We generate something which looks like
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--
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-- > INSERT INTO
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-- > ...
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-- > ON CONFLICT DO UPDATE SET
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-- > ...
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-- > RETURNING
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-- > *,
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-- > CASE WHEN xmax = 0
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-- > THEN {insert_cond}
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-- > ELSE {update_cond}
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-- > END
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-- > AS "check__constraint"
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--
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-- See @https://stackoverflow.com/q/34762732@ for more information on the use of
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-- the @xmax@ system column.
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insertOrUpdateCheckExpr
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:: QualifiedTable
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-> Maybe (ConflictClauseP1 ('Postgres pgKind) S.SQLExp)
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-> S.BoolExp
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-> Maybe S.BoolExp
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-> S.Extractor
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insertOrUpdateCheckExpr qt (Just _conflict) insCheck (Just updCheck) =
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asCheckErrorExtractor $
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S.SECond
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(S.BECompare
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S.SEQ
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(S.SEQIdentifier (S.QIdentifier (S.mkQual qt) (Identifier "xmax")))
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(S.SEUnsafe "0"))
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(insertCheckConstraint insCheck)
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(insertCheckConstraint updCheck)
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insertOrUpdateCheckExpr _ _ insCheck _ =
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-- If we won't generate an ON CONFLICT clause, there is no point
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-- in testing xmax. In particular, views don't provide the xmax
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-- system column, but we don't provide ON CONFLICT for views,
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-- even if they are auto-updatable, so we can fortunately avoid
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-- having to test the non-existent xmax value.
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--
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-- Alternatively, if there is no update check constraint, we should
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-- use the insert check constraint, for backwards compatibility.
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asCheckErrorExtractor $ insertCheckConstraint insCheck
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