Safe Haskell	None
Language	Haskell2010

Hasura.Backends.MSSQL.FromIr

Description

The modules in the Hasura.Backends.MSSQL.FromIr namespace translates the RQL IR into TSQL, the SQL dialect of MSSQL, as defined in abstract syntax in Hasura.Backends.MSSQL.Types.

The translation happens in the FromIr monad, which manages identifier scoping and error collection.

The actual rendering of this AST into TSQL text happens in Hasura.Backends.MSSQL.ToQuery.

Synopsis

newtype FromIr a = FromIr {
- unFromIr :: StateT (Map Text Int) (Validate (NonEmpty Error)) a
}
runFromIr :: MonadError QErr m => FromIr a -> m a
data Error
- = UnsupportedOpExpG (OpExpG 'MSSQL Expression)
- | FunctionNotSupported
data NameTemplate
- = ArrayRelationTemplate Text
- | ArrayAggregateTemplate Text
- | ObjectRelationTemplate Text
- | TableTemplate Text
- | ForOrderAlias Text
generateAlias :: NameTemplate -> FromIr Text

Documentation

newtype FromIr a Source #

The central Monad used throughout for all conversion functions.

It has the following features:

It's a MonadValidate, so it'll continue going when it encounters Errors to accumulate as many as possible.
It has a facility for generating fresh, unique aliases, which lets the translation output retain a resemblance with source names without the translation process needing to be bothered about potential name shadowing. See generateAlias.

Constructors

FromIr
Fields unFromIr :: StateT (Map Text Int) (Validate (NonEmpty Error)) a

Instances

Instances details

Monad FromIr Source #
Instance details Defined in Hasura.Backends.MSSQL.FromIr Methods (>>=) :: FromIr a -> (a -> FromIr b) -> FromIr b # (>>) :: FromIr a -> FromIr b -> FromIr b # return :: a -> FromIr a #
Functor FromIr Source #
Instance details Defined in Hasura.Backends.MSSQL.FromIr Methods fmap :: (a -> b) -> FromIr a -> FromIr b # (<$) :: a -> FromIr b -> FromIr a #
Applicative FromIr Source #
Instance details Defined in Hasura.Backends.MSSQL.FromIr Methods pure :: a -> FromIr a # (<>) :: FromIr (a -> b) -> FromIr a -> FromIr b # liftA2 :: (a -> b -> c) -> FromIr a -> FromIr b -> FromIr c # (>) :: FromIr a -> FromIr b -> FromIr b # (<*) :: FromIr a -> FromIr b -> FromIr a #
MonadValidate (NonEmpty Error) FromIr Source #
Instance details Defined in Hasura.Backends.MSSQL.FromIr Methods refute :: NonEmpty Error -> FromIr a dispute :: NonEmpty Error -> FromIr () tolerate :: FromIr a -> FromIr (Maybe a)

runFromIr :: MonadError QErr m => FromIr a -> m a Source #

Run a FromIr action, throwing errors that have been collected using the supplied action.

data Error Source #

Errors that may happen during translation.

Constructors

UnsupportedOpExpG (OpExpG 'MSSQL Expression)
FunctionNotSupported

Instances

Instances details

Eq Error Source #
Instance details Defined in Hasura.Backends.MSSQL.FromIr Methods (==) :: Error -> Error -> Bool # (/=) :: Error -> Error -> Bool #
Show Error Source #
Instance details Defined in Hasura.Backends.MSSQL.FromIr Methods showsPrec :: Int -> Error -> ShowS # show :: Error -> String # showList :: [Error] -> ShowS #
MonadValidate (NonEmpty Error) FromIr Source #
Instance details Defined in Hasura.Backends.MSSQL.FromIr Methods refute :: NonEmpty Error -> FromIr a dispute :: NonEmpty Error -> FromIr () tolerate :: FromIr a -> FromIr (Maybe a)

data NameTemplate Source #

Hints about the type of entity that generateAlias is producing an alias for.

Constructors

ArrayRelationTemplate Text
ArrayAggregateTemplate Text
ObjectRelationTemplate Text
TableTemplate Text
ForOrderAlias Text

generateAlias :: NameTemplate -> FromIr Text Source #

Generate a fresh alias for a given entity to remove ambiguity and naming conflicts between scopes at the TSQL level.

Names are generated in the form type_name_occurrence, where:

type hints at the type of entity,
name refers to the source name being aliased, and
occurrence is an integer counter that distinguishes each occurrence of type_name.

Example outputs:

do
  "ar_articles_1" <- generateAlias (ArrayRelationTemplate "articles")
  "ar_articles_2" <- generateAlias (ArrayRelationTemplate "articles")
  "t_users_1"     <- generateAlias (TableTemplate "users")