Safe Haskell	None
Language	Haskell2010

GraphQL.Internal.Value.FromValue

Description

Synopsis

class FromValue a where
- fromValue :: Value' ConstScalar -> Either Text a
prop_roundtripValue :: forall a. (Eq a, ToValue a, FromValue a) => a -> Bool
wrongType :: (MonadError Text m, Show a) => Text -> a -> m b

Documentation

class FromValue a where Source #

a can be converted from a GraphQL Value to a Haskell value.

The FromValue instance converts Value to the type expected by the handler function. It is the boundary between incoming data and your custom application Haskell types.

FromValue has a generic instance for converting input objects to records.

Minimal complete definition

Nothing

Methods

fromValue :: Value' ConstScalar -> Either Text a Source #

Convert an already-parsed value into a Haskell value, generally to be passed to a handler.

fromValue :: (Generic a, GenericFromValue (Rep a)) => Value' ConstScalar -> Either Text a Source #

Convert an already-parsed value into a Haskell value, generally to be passed to a handler.

Instances

FromValue Bool Source #
Instance details Defined in GraphQL.Internal.Value.FromValue Methods fromValue :: Value' ConstScalar -> Either Text Bool Source #
FromValue Double Source #
Instance details Defined in GraphQL.Internal.Value.FromValue Methods fromValue :: Value' ConstScalar -> Either Text Double Source #
FromValue Int32 Source #
Instance details Defined in GraphQL.Internal.Value.FromValue Methods fromValue :: Value' ConstScalar -> Either Text Int32 Source #
FromValue Text Source #
Instance details Defined in GraphQL.Internal.Value.FromValue Methods fromValue :: Value' ConstScalar -> Either Text Text Source #
FromValue v => FromValue [v] Source #
Instance details Defined in GraphQL.Internal.Value.FromValue Methods fromValue :: Value' ConstScalar -> Either Text [v] Source #
FromValue v => FromValue (Maybe v) Source #
Instance details Defined in GraphQL.Internal.Value.FromValue Methods fromValue :: Value' ConstScalar -> Either Text (Maybe v) Source #
FromValue v => FromValue (NonEmpty v) Source #
Instance details Defined in GraphQL.Internal.Value.FromValue Methods fromValue :: Value' ConstScalar -> Either Text (NonEmpty v) Source #

prop_roundtripValue :: forall a. (Eq a, ToValue a, FromValue a) => a -> Bool Source #

Anything that can be converted to a value and from a value should roundtrip.

wrongType :: (MonadError Text m, Show a) => Text -> a -> m b Source #

Throw an error saying that value does not have the expected type.