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98d6a635a1
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/5036 GitOrigin-RevId: e6d076edb1a5f6664c941b84d06329ece43751cb
71 lines
2.5 KiB
Haskell
71 lines
2.5 KiB
Haskell
-- | Postgres Translate Mutation
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--
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-- Provide a combinator for generating a Postgres SQL SELECT statement for the
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-- selected columns in mutation queries.
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--
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-- See 'Hasura.Backends.Postgres.Execute.Mutation' and note
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-- [Prepared statements in Mutations]
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module Hasura.Backends.Postgres.Translate.Mutation
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( mkSelectExpFromColumnValues,
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)
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where
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import Data.HashMap.Strict qualified as Map
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import Data.Text.Extended
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import Hasura.Backends.Postgres.SQL.DML qualified as S
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import Hasura.Backends.Postgres.SQL.Types
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import Hasura.Backends.Postgres.SQL.Value
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import Hasura.Backends.Postgres.Types.Column
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import Hasura.Base.Error
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import Hasura.Prelude
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import Hasura.RQL.Types.Column
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import Hasura.RQL.Types.Table
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import Hasura.SQL.Backend
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import Hasura.SQL.Types
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-- | Note:- Using sorted columns is necessary to enable casting the rows returned by VALUES expression to table type.
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-- For example, let's consider the table, `CREATE TABLE test (id serial primary key, name text not null, age int)`.
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-- The generated values expression should be in order of columns;
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-- `SELECT ("row"::table).* VALUES (1, 'Robert', 23) AS "row"`.
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mkSelectExpFromColumnValues ::
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forall pgKind m.
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MonadError QErr m =>
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QualifiedTable ->
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[ColumnInfo ('Postgres pgKind)] ->
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[ColumnValues ('Postgres pgKind) TxtEncodedVal] ->
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m S.Select
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mkSelectExpFromColumnValues qt allCols = \case
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[] -> return selNoRows
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colVals -> do
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tuples <- mapM mkTupsFromColVal colVals
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let fromItem = S.FIValues (S.ValuesExp tuples) (S.toTableAlias rowAlias) Nothing
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return
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S.mkSelect
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{ S.selExtr = [extractor],
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S.selFrom = Just $ S.FromExp [fromItem]
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}
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where
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rowAlias = Identifier "row"
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extractor = S.selectStar' $ S.QualifiedIdentifier rowAlias $ Just $ S.TypeAnn $ toSQLTxt qt
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sortedCols = sortCols allCols
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mkTupsFromColVal colVal =
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fmap S.TupleExp $
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forM sortedCols $ \ci -> do
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let pgCol = ciColumn ci
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val <-
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onNothing (Map.lookup pgCol colVal) $
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throw500 $ "column " <> pgCol <<> " not found in returning values"
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pure $ txtEncodedToSQLExp (ciType ci) val
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selNoRows =
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S.mkSelect
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{ S.selExtr = [S.selectStar],
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S.selFrom = Just $ S.mkSimpleFromExp qt,
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S.selWhere = Just $ S.WhereFrag $ S.BELit False
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}
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txtEncodedToSQLExp colTy = \case
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TENull -> S.SENull
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TELit textValue ->
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withScalarTypeAnn (unsafePGColumnToBackend colTy) $ S.SELit textValue
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