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graphql-engine/server/src-lib/Hasura/Backends/Postgres/Translate/Select/AnnotatedFieldJSON.hs
Evie Ciobanu 0060a48009 server: minor nit-picks for the Postgres Select module split
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/4338
GitOrigin-RevId: c2125275b32a5084c5a96afba79d4cb6c65687a8
2022-04-22 17:19:58 +00:00

50 lines
2.1 KiB
Haskell

-- | This module defines the type class 'PostgresAnnotatedFieldJSON'.
module Hasura.Backends.Postgres.Translate.Select.AnnotatedFieldJSON
( PostgresAnnotatedFieldJSON (..),
)
where
import Data.Text qualified as T
import Hasura.Backends.Postgres.SQL.DML qualified as S
import Hasura.Backends.Postgres.Translate.Select.Internal.Helpers (withJsonBuildObj)
import Hasura.Prelude
import Hasura.RQL.Types.Common (FieldName (getFieldNameTxt))
import Hasura.SQL.Backend (PostgresKind (..))
class PostgresAnnotatedFieldJSON (pgKind :: PostgresKind) where
annRowToJson :: FieldName -> [(FieldName, S.SQLExp)] -> (S.Alias, S.SQLExp)
instance PostgresAnnotatedFieldJSON 'Vanilla where
annRowToJson fieldAlias fieldExps =
-- postgres ignores anything beyond 63 chars for an iden
-- in this case, we'll need to use json_build_object function
-- json_build_object is slower than row_to_json hence it is only
-- used when needed
if any ((> 63) . T.length . getFieldNameTxt . fst) fieldExps
then withJsonBuildObj fieldAlias $ concatMap toJsonBuildObjectExps fieldExps
else withRowToJSON fieldAlias $ map toRowToJsonExtr fieldExps
where
toJsonBuildObjectExps (fieldName, fieldExp) =
[S.SELit $ getFieldNameTxt fieldName, fieldExp]
toRowToJsonExtr (fieldName, fieldExp) =
S.Extractor fieldExp $ Just $ S.toAlias fieldName
-- uses row_to_json to build a json object
withRowToJSON ::
FieldName -> [S.Extractor] -> (S.Alias, S.SQLExp)
withRowToJSON parAls extrs =
(S.toAlias parAls, jsonRow)
where
jsonRow = S.applyRowToJson extrs
instance PostgresAnnotatedFieldJSON 'Citus where
annRowToJson fieldAlias fieldExps =
-- Due to the restrictions Citus imposes on joins between tables of various
-- distribution types we cannot use row_to_json and have to only rely on
-- json_build_object.
withJsonBuildObj fieldAlias $ concatMap toJsonBuildObjectExps fieldExps
where
toJsonBuildObjectExps (fieldName, fieldExp) =
[S.SELit $ getFieldNameTxt fieldName, fieldExp]