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graphql-engine/server/src-lib/Hasura/Backends/Postgres/Translate/Select/Streaming.hs
Philip Lykke Carlsen df10ccf310 fix(pg): Support aliased fields for Native Query object relations
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/9374
GitOrigin-RevId: 073e51480e2be97e32938fa61a3547374e04ead8
2023-05-31 15:42:50 +00:00

161 lines
6.7 KiB
Haskell

-- | This module defines the top-level translation functions pertaining to
-- streaming selects into Postgres AST.
--
-- Streaming subscriptions are subscriptions based on a user-provided cursor
-- column. Unlike live queries, streaming subscriptions can be used to only get
-- the part that has changed in the query's response, although this will be
-- dependent on the user's choice of the cursor column. The streaming starts
-- from the initial value provided by the user.
module Hasura.Backends.Postgres.Translate.Select.Streaming
( mkStreamSQLSelect,
selectStreamQuerySQL,
)
where
import Control.Monad.Writer.Strict (runWriter)
import Database.PG.Query (Query)
import Hasura.Backends.Postgres.SQL.DML qualified as S
import Hasura.Backends.Postgres.SQL.Types
import Hasura.Backends.Postgres.SQL.Value (withConstructorFn)
import Hasura.Backends.Postgres.Translate.Select.AnnotatedFieldJSON
import Hasura.Backends.Postgres.Translate.Select.Internal.Aliases (contextualizeBaseTableColumn)
import Hasura.Backends.Postgres.Translate.Select.Internal.Extractor (asJsonAggExtr)
import Hasura.Backends.Postgres.Translate.Select.Internal.GenerateSelect (generateSQLSelectFromArrayNode)
import Hasura.Backends.Postgres.Translate.Select.Internal.Helpers (selectToSelectWith, toQuery)
import Hasura.Backends.Postgres.Translate.Select.Internal.Process (processAnnSimpleSelect)
import Hasura.Backends.Postgres.Translate.Types
( CustomSQLCTEs,
MultiRowSelectNode (MultiRowSelectNode),
PermissionLimitSubQuery (PLSQNotRequired),
SelectNode (SelectNode),
SelectWriter (..),
SourcePrefixes (SourcePrefixes),
initialNativeQueryFreshIdStore,
orderByForJsonAgg,
)
import Hasura.Backends.Postgres.Types.Column (unsafePGColumnToBackend)
import Hasura.Prelude
import Hasura.RQL.IR.BoolExp
( AnnBoolExpFld (AVColumn),
GBoolExp (BoolField),
OpExpG (AGT, ALT),
andAnnBoolExps,
)
import Hasura.RQL.IR.OrderBy (OrderByItemG (OrderByItemG))
import Hasura.RQL.IR.Select
import Hasura.RQL.Types.Backend (Backend)
import Hasura.RQL.Types.BackendType (BackendType (Postgres))
import Hasura.RQL.Types.Column
( ColumnInfo (ciColumn, ciName),
ColumnValue (cvType),
)
import Hasura.RQL.Types.Common
( FieldName (FieldName),
JsonAggSelect (JASMultipleRows),
getFieldNameTxt,
)
import Hasura.RQL.Types.Subscription
( CursorOrdering (CODescending),
)
import Hasura.SQL.Types
( CollectableType (CollectableTypeArray, CollectableTypeScalar),
)
import Language.GraphQL.Draft.Syntax qualified as G
selectStreamQuerySQL ::
forall pgKind.
(Backend ('Postgres pgKind), PostgresAnnotatedFieldJSON pgKind) =>
AnnSimpleStreamSelect ('Postgres pgKind) ->
Query
selectStreamQuerySQL =
toQuery
. selectToSelectWith
. mkStreamSQLSelect
mkStreamSQLSelect ::
forall pgKind m.
( Backend ('Postgres pgKind),
PostgresAnnotatedFieldJSON pgKind,
MonadWriter CustomSQLCTEs m
) =>
AnnSimpleStreamSelect ('Postgres pgKind) ->
m S.Select
mkStreamSQLSelect (AnnSelectStreamG () fields from perm args strfyNum) = do
let cursorArg = _ssaCursorArg args
cursorColInfo = _sciColInfo cursorArg
annOrderbyCol = AOCColumn cursorColInfo
basicOrderType =
bool S.OTAsc S.OTDesc $ _sciOrdering cursorArg == CODescending
orderByItems =
nonEmpty $ pure $ OrderByItemG (Just basicOrderType) annOrderbyCol Nothing
cursorBoolExp =
let orderByOpExp = bool ALT AGT $ basicOrderType == S.OTAsc
sqlExp =
fromResVars
(CollectableTypeScalar $ unsafePGColumnToBackend $ cvType (_sciInitialValue cursorArg))
["cursor", G.unName $ ciName cursorColInfo]
in BoolField $ AVColumn cursorColInfo [(orderByOpExp sqlExp)]
selectArgs =
noSelectArgs
{ _saWhere =
Just $ maybe cursorBoolExp (andAnnBoolExps cursorBoolExp) $ _ssaWhere args,
_saOrderBy = orderByItems,
_saLimit = Just $ _ssaBatchSize args
}
sqlSelect = AnnSelectG fields from perm selectArgs strfyNum Nothing
permLimitSubQuery = PLSQNotRequired
((selectSource, nodeExtractors), SelectWriter {_swJoinTree = joinTree, _swCustomSQLCTEs = customSQLCTEs}) =
runWriter
$ flip runReaderT strfyNum
$ flip evalStateT initialNativeQueryFreshIdStore
$ processAnnSimpleSelect sourcePrefixes rootFldName permLimitSubQuery sqlSelect
selectNode = SelectNode nodeExtractors joinTree
topExtractor =
asJsonAggExtr JASMultipleRows rootFldAls permLimitSubQuery
$ orderByForJsonAgg selectSource
cursorLatestValueExp :: S.SQLExp =
let columnAlias = ciName cursorColInfo
pgColumn = ciColumn cursorColInfo
mkMaxOrMinSQLExp maxOrMin col =
S.SEFnApp maxOrMin [S.SEIdentifier col] Nothing
maxOrMinTxt = bool "MIN" "MAX" $ basicOrderType == S.OTAsc
-- text encoding the cursor value while it's fetched from the DB, because
-- we can then directly reuse this value, otherwise if this were json encoded
-- then we'd have to parse the value and then convert it into a text encoded value
colExp =
[ S.SELit (G.unName columnAlias),
S.SETyAnn
( mkMaxOrMinSQLExp maxOrMinTxt
$ toIdentifier
$ contextualizeBaseTableColumn rootFldIdentifier pgColumn
)
S.textTypeAnn
]
in -- SELECT json_build_object ('col1', MAX(col1) :: text)
S.SEFnApp "json_build_object" colExp Nothing
cursorLatestValueExtractor = S.Extractor cursorLatestValueExp (Just $ S.toColumnAlias $ Identifier "cursor")
arrayNode = MultiRowSelectNode [topExtractor, cursorLatestValueExtractor] selectNode
tell customSQLCTEs
pure $ generateSQLSelectFromArrayNode selectSource arrayNode $ S.BELit True
where
rootFldIdentifier = TableIdentifier $ getFieldNameTxt rootFldName
sourcePrefixes = SourcePrefixes (tableIdentifierToIdentifier rootFldIdentifier) (tableIdentifierToIdentifier rootFldIdentifier)
rootFldName = FieldName "root"
rootFldAls = S.toColumnAlias $ toIdentifier rootFldName
-- TODO: these functions also exist in `resolveMultiplexedValue`, de-duplicate these!
fromResVars pgType jPath =
addTypeAnnotation pgType
$ S.SEOpApp
(S.SQLOp "#>>")
[ S.SEQIdentifier $ S.QIdentifier (S.QualifiedIdentifier (TableIdentifier "_subs") Nothing) (Identifier "result_vars"),
S.SEArray $ map S.SELit jPath
]
addTypeAnnotation pgType =
flip S.SETyAnn (S.mkTypeAnn pgType) . case pgType of
CollectableTypeScalar scalarType -> withConstructorFn scalarType
CollectableTypeArray _ -> id