graphql-engine/server/src-lib/Hasura/SQL/Backend.hs
Sibi Prabakaran 385d27449e mysql: Metadata awareness
https://github.com/hasura/graphql-engine-mono/pull/1599

Co-authored-by: Chris Done <11019+chrisdone@users.noreply.github.com>
Co-authored-by: Aniket Deshpande <922486+aniketd@users.noreply.github.com>
Co-authored-by: Abby Sassel <3883855+sassela@users.noreply.github.com>
GitOrigin-RevId: 4df4a8ff00fa8ef311a85199d66abe4cc10adc8c
2021-07-15 12:45:51 +00:00

75 lines
2.2 KiB
Haskell

module Hasura.SQL.Backend
( PostgresKind(..)
, BackendType(..)
, backendShortName
, supportedBackends
) where
import Hasura.Prelude
import Data.Aeson
import Data.List.Extended (uniques)
import Data.Proxy
import Data.Text (unpack)
import Data.Text.Extended
import Hasura.Incremental
-- | Argument to Postgres; we represent backends which are variations on Postgres as sub-types of
-- Postgres. This value indicates which "flavour" of Postgres a backend is.
data PostgresKind
= Vanilla
| Citus
deriving (Show, Eq, Ord)
-- | An enum that represents each backend we support.
data BackendType
= Postgres PostgresKind
| MSSQL
| BigQuery
| MySQL
deriving (Show, Eq, Ord)
-- | The name of the backend, as we expect it to appear in our metadata and API.
instance ToTxt BackendType where
toTxt (Postgres Vanilla) = "postgres"
toTxt (Postgres Citus) = "citus"
toTxt MSSQL = "mssql"
toTxt BigQuery = "bigquery"
toTxt MySQL = "mysql"
-- | The FromJSON instance uses this lookup mechanism to avoid having to duplicate and hardcode the
-- backend string. We accept both the short form and the long form of the backend's name.
instance FromJSON BackendType where
parseJSON = withText "backend type" \name -> do
let knownBackends = supportedBackends >>= \b ->
[ (toTxt b, b) -- long form
, (backendShortName b, b) -- short form
]
uniqueBackends = commaSeparated $ fst <$> uniques knownBackends
lookup name knownBackends `onNothing`
fail ("got: " <> unpack name <> ", expected one of: " <> unpack uniqueBackends)
instance ToJSON BackendType where
toJSON = String . toTxt
instance Cacheable (Proxy (b :: BackendType))
-- | Some generated APIs use a shortened version of the backend's name rather than its full
-- name. This function returns the "short form" of a backend, if any.
backendShortName :: BackendType -> Text
backendShortName = \case
Postgres Vanilla -> "pg"
b -> toTxt b
supportedBackends :: [BackendType]
supportedBackends =
[ Postgres Vanilla
, Postgres Citus
, MSSQL
, BigQuery
, MySQL
]