graphql-engine/server/src-lib/Hasura/Backends/Postgres/Translate/Select/Connection.hs

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-- | This module defines the top-level translation functions pertaining to
-- translating Connection (i.e. Relay) queries into Postgres AST.
module Hasura.Backends.Postgres.Translate.Select.Connection
( connectionSelectQuerySQL,
mkConnectionSelect,
)
where
import Control.Monad.Writer (runWriter)
import Database.PG.Query (Query, fromBuilder)
import Hasura.Backends.Postgres.SQL.DML qualified as S
import Hasura.Backends.Postgres.SQL.IdentifierUniqueness (prefixNumToAliasesSelectWith)
import Hasura.Backends.Postgres.SQL.Types
import Hasura.Backends.Postgres.Translate.Select.AnnotatedFieldJSON
import Hasura.Backends.Postgres.Translate.Select.Internal.GenerateSelect (connectionToSelectWith)
import Hasura.Backends.Postgres.Translate.Select.Internal.Process (processConnectionSelect)
import Hasura.Backends.Postgres.Translate.Types
import Hasura.Prelude
import Hasura.RQL.IR.Select
( AnnSelectG (_asnStrfyNum),
ConnectionSelect (_csSelect),
)
import Hasura.RQL.Types.Backend (Backend)
import Hasura.RQL.Types.Common (FieldName (FieldName))
import Hasura.SQL.Backend (BackendType (Postgres))
import Hasura.SQL.Types (ToSQL (toSQL))
-- | Translates IR to Postgres queries for "connection" queries (used for Relay).
--
-- See 'mkConnectionSelect' for the Postgres AST.
connectionSelectQuerySQL ::
forall pgKind.
( Backend ('Postgres pgKind),
PostgresAnnotatedFieldJSON pgKind
) =>
ConnectionSelect ('Postgres pgKind) Void S.SQLExp ->
Query
connectionSelectQuerySQL =
fromBuilder . toSQL . mkConnectionSelect
mkConnectionSelect ::
forall pgKind.
( Backend ('Postgres pgKind),
PostgresAnnotatedFieldJSON pgKind
) =>
ConnectionSelect ('Postgres pgKind) Void S.SQLExp ->
S.SelectWithG S.Select
mkConnectionSelect connectionSelect =
let ((connectionSource, topExtractor, nodeExtractors), joinTree) =
runWriter $
flip runReaderT strfyNum $
processConnectionSelect
sourcePrefixes
rootFieldName
(S.toTableAlias rootIdentifier)
mempty
connectionSelect
selectNode =
MultiRowSelectNode [topExtractor] $
SelectNode nodeExtractors joinTree
in prefixNumToAliasesSelectWith $
connectionToSelectWith (S.toTableAlias rootIdentifier) connectionSource selectNode
where
strfyNum = _asnStrfyNum $ _csSelect connectionSelect
rootFieldName = FieldName "root"
rootIdentifier = toIdentifier rootFieldName
sourcePrefixes = SourcePrefixes rootIdentifier rootIdentifier