WebGear.Core.Trait.Path

Middlewares related to request paths.

All the middlewares below attempt to match components of the request path. In case of a mismatch, they abandon the current handler and tries the next handler.

Documentation

newtype Path

A path component which is literally matched against the request but discarded after that.

Constructors

Path Text

Instances

type Absence Path

Defined in WebGear.Core.Trait.Path

type Absence Path = ()

type Attribute Path Request

Defined in WebGear.Core.Trait.Path

type Attribute Path Request = ()

type Prerequisite Path ts

Defined in WebGear.Core.Trait.Path

type Prerequisite Path ts = ()

data PathVar (tag :: Symbol) (val :: Type)

A path variable that is extracted and converted to a value of type val. The tag is usually a type-level symbol (string) to uniquely identify this variable.

Constructors

PathVar

Instances

type Absence (PathVar tag val)

Defined in WebGear.Core.Trait.Path

type Absence (PathVar tag val) = PathVarError

type Attribute (PathVar tag val) Request

Defined in WebGear.Core.Trait.Path

type Attribute (PathVar tag val) Request = val

type Prerequisite (PathVar tag val) ts

Defined in WebGear.Core.Trait.Path

type Prerequisite (PathVar tag val) ts = ()

data PathVarError

Failure to extract a PathVar

Constructors

PathVarNotFound

PathVarParseError Text

Instances

Read PathVarError

Defined in WebGear.Core.Trait.Path

Methods

readsPrec :: Int -> ReadS PathVarError

readList :: ReadS [PathVarError]

readPrec :: ReadPrec PathVarError

readListPrec :: ReadPrec [PathVarError]

Show PathVarError

Defined in WebGear.Core.Trait.Path

Methods

showsPrec :: Int -> PathVarError -> ShowS

show :: PathVarError -> String

showList :: [PathVarError] -> ShowS

Eq PathVarError

Defined in WebGear.Core.Trait.Path

Methods

(==) :: PathVarError -> PathVarError -> Bool

(/=) :: PathVarError -> PathVarError -> Bool

data PathEnd

Trait to indicate that no more path components are present in the request

Constructors

PathEnd

Instances

type Absence PathEnd

Defined in WebGear.Core.Trait.Path

type Absence PathEnd = ()

type Attribute PathEnd Request

Defined in WebGear.Core.Trait.Path

type Attribute PathEnd Request = ()

type Prerequisite PathEnd ts

Defined in WebGear.Core.Trait.Path

type Prerequisite PathEnd ts = ()

path :: (Get h Path, ArrowChoice h, ArrowError RouteMismatch h) => Text -> Middleware h ts (Path : ts)

A middleware that literally matches path s.

The symbol s could contain one or more parts separated by a forward slash character. The route will be rejected if there is no match.

For example, the following code could be used to match the URL path "a/b/c" and then invoke handler:

path "a/b/c" handler

pathVar :: forall tag val h ts. (Get h (PathVar tag val), ArrowChoice h, ArrowError RouteMismatch h) => Middleware h ts (PathVar tag val : ts)

A middleware that captures a path variable from a single path component.

The value captured is converted to a value of type val. The route will be rejected if the value is not found or cannot be converted.

For example, the following code could be used to read a path component as Int tagged with the symbol "objId", and then invoke handler:

pathVar @"objId" @Int handler

pathEnd :: (Get h PathEnd, ArrowChoice h, ArrowError RouteMismatch h) => Middleware h ts (PathEnd : ts)

A middleware that verifies that end of path is reached.

match :: QuasiQuoter

Produces middleware(s) to match an optional HTTP method and some path components.

This middleware matches a prefix of path components, the remaining components can be matched by subsequent uses of match.

This quasiquoter can be used in several ways:

QuasiQuoter	Equivalent Middleware
[match| /a/b/c |]	path "/a/b/c"
[match| /a/b/objId:Int/d |]	path "/a/b" . pathVar @"objId" @Int . path "d"
[match| GET /a/b/c |]	method GET . path "/a/b/c"
[match| GET /a/b/objId:Int/d |]	method GET . path "/a/b" . pathVar @"objId" @Int . path "d"

route :: QuasiQuoter

Produces middleware(s) to match an optional HTTP method and the entire request path.

This middleware is intended to be used in cases where the entire path needs to be matched. Use match middleware to match only an initial portion of the path.

This quasiquoter can be used in several ways:

QuasiQuoter	Equivalent Middleware
[route| /a/b/c |]	path "/a/b/c" . pathEnd
[route| /a/b/objId:Int/d |]	path "/a/b" . pathVar @"objId" @Int . path "d" . pathEnd
[route| GET /a/b/c |]	method GET . path "/a/b/c" . pathEnd
[route| GET /a/b/objId:Int/d |]	method GET . path "/a/b" . pathVar @"objId" @Int . path "d" . pathEnd)