Servant.Record

This module provides functions and instances for working with query parameter records.

Documentation

data RecordParam (mod :: Symbol -> Exp Symbol) (a :: Type)

RecordParam uses fields in a record to represent query parameters.

For each record field:

• The modified record field name becomes a query parameter name.
• The record field type becomes the query parameter type.

For example, this API:

type API = "users" :> (QueryParam "category" Category :>
                       QueryParam' '[Required, Strict] "sort_by" SortBy :>
                       QueryFlag "with_schema" :>
                       QueryParams "filters" Filter :>
                       Get '[JSON] User)

can be written using records:

data DropPrefixExp :: sym -> Exp sym

type instance Eval (DropPrefixExp sym) = DropPrefix sym

data UserParams = UserParams
  { _userParams_category :: Maybe Category
  , _userParams_sort_by :: SortBy
  , _userParams_with_schema :: Bool
  , _userParams_filters :: [Filter]
  }

type API = "users" :> RecordParam DropPrefixExp UserParams :> Get '[JSON] User

Here, DropPrefixExp wraps a sym into Exp.

The instance of Eval for DropPrefixExp sym drops the prefix of that sym via DropPrefix.

DropPrefix is applied to the fields of UserParams.

The "_userParams_category" record field corresponds to the query parameter "category".

Instances

(Generic a, GHasLink mod (Rep a) sub) => HasLink (RecordParam mod a :> sub :: Type)

Defined in Servant.Record

Associated Types

type MkLink (RecordParam mod a :> sub) a

Methods

toLink :: (Link -> a0) -> Proxy (RecordParam mod a :> sub) -> Link -> MkLink (RecordParam mod a :> sub) a0

type MkLink (RecordParam mod a :> sub :: Type) b

Defined in Servant.Record

type MkLink (RecordParam mod a :> sub :: Type) b = a -> MkLink sub b

type family UnRecordParam (mod :: Symbol -> Exp Symbol) (x :: Type) :: Type where ...

Type family for rewriting a RecordParam API to a regular servant API. This family is useful for defining instances of classes that extract information from the API type, such as classes from servant-swagger or servant-foreign.

Typical use:

instance SomeClass (UnRecordParam (RecordParam mod a :> api))) =>
         SomeClass (RecordParam mod a :> api) where
   someMethod _ = someMethod (Proxy :: Proxy (UnRecordParam (RecordParam mod a :> api))

Equations

UnRecordParam mod (a :> b) = ServantAppend (UnRecordParam mod a) b

UnRecordParam mod (RecordParam mod a) = UnRecordParam mod (Rep a ())

UnRecordParam mod (D1 m c d) = UnRecordParam mod (c d)

UnRecordParam mod ((a :*: b) d) = ServantAppend (UnRecordParam mod (a d)) (UnRecordParam mod (b d))

UnRecordParam mod (C1 m a d) = UnRecordParam mod (a d)

UnRecordParam mod (S1 ('MetaSel ('Just sym) d1 d2 d3) (Rec0 Bool) d) = QueryFlag (Eval (mod sym))

UnRecordParam mod (S1 ('MetaSel ('Just sym) d1 d2 d3) (Rec0 [a]) d) = QueryParams (Eval (mod sym)) a

UnRecordParam mod (S1 ('MetaSel ('Just sym) d1 d2 d3) (Rec0 (Maybe a)) d) = QueryParam' [Optional, Strict] (Eval (mod sym)) a

UnRecordParam mod (S1 ('MetaSel ('Just sym) d1 d2 d3) (Rec0 a) d) = QueryParam' [Required, Strict] (Eval (mod sym)) a