WebGear.Core.Trait.Body

Traits and middlewares to handle request and response body payloads.

There are a number of ways to extract a body from a request:

The requestBody middleware attempts to convert the body to a Haskell value or invoke an error handler if that fails.

The jsonRequestBody middleware attempts to convert a JSON formatted body to a Haskell value or invoke an error handler if that fails. It uses the standard "application/json" media type.

The jsonRequestBody' middleware is similar but supports custom media types.

Similarly, there are a number of ways to set a response body:

The easiest option is to use one of respondA, respondJsonA, or respondJsonA' middlewares. These middlewares generate a response from an HTTP status and a response body.

If you need finer control over setting the body, use one of setBody, setBodyWithoutContentType, setJSONBody, setJSONBodyWithoutContentType, or setJSONBody'. These arrows accept a linked response and a body and sets the body in the response. You can generate an input response object using functions from WebGear.Core.Trait.Status module.

Traits

newtype Body (t :: Type)

Request or response body with a type t.

Constructors

Body (Maybe MediaType)

Instances

Trait (Body t) Request

Defined in WebGear.Core.Trait.Body

Associated Types

type Attribute (Body t) Request

Trait (Body t) Response

Defined in WebGear.Core.Trait.Body

Associated Types

type Attribute (Body t) Response

TraitAbsence (Body t) Request

Defined in WebGear.Core.Trait.Body

Associated Types

type Absence (Body t) Request

type Absence (Body t) Request

Defined in WebGear.Core.Trait.Body

type Absence (Body t) Request = Text

type Attribute (Body t) Request

Defined in WebGear.Core.Trait.Body

type Attribute (Body t) Request = t

type Attribute (Body t) Response

Defined in WebGear.Core.Trait.Body

type Attribute (Body t) Response = t

newtype JSONBody (t :: Type)

A Trait for converting a JSON formatted body into a value.

Constructors

JSONBody (Maybe MediaType)

Instances

Trait (JSONBody t) Request

Defined in WebGear.Core.Trait.Body

Associated Types

type Attribute (JSONBody t) Request

Trait (JSONBody t) Response

Defined in WebGear.Core.Trait.Body

Associated Types

type Attribute (JSONBody t) Response

TraitAbsence (JSONBody t) Request

Defined in WebGear.Core.Trait.Body

Associated Types

type Absence (JSONBody t) Request

type Absence (JSONBody t) Request

Defined in WebGear.Core.Trait.Body

type Absence (JSONBody t) Request = Text

type Attribute (JSONBody t) Request

Defined in WebGear.Core.Trait.Body

type Attribute (JSONBody t) Request = t

type Attribute (JSONBody t) Response

Defined in WebGear.Core.Trait.Body

type Attribute (JSONBody t) Response = t

Middlewares

requestBody

Arguments

:: forall t h req. (Get h (Body t) Request, ArrowChoice h)

=> Maybe MediaType

Optional media type of the body

-> h (Linked req Request, Text) Response

Error handler in case body cannot be retrieved

-> Middleware h req (Body t ': req)

Middleware to extract a request body.

The nextHandler is invoked after successfully extracting the body and the errorHandler is invoked when there is an error.

Usage:

requestBody @t (Just "text/plain") errorHandler nextHandler

jsonRequestBody'

Arguments

:: forall t h req. (Get h (JSONBody t) Request, ArrowChoice h)

=> Maybe MediaType

Optional media type of the body

-> h (Linked req Request, Text) Response

Error handler in case body cannot be retrieved

-> Middleware h req (JSONBody t ': req)

Parse the request body as JSON and convert it to a value of type t.

The nextHandler is invoked when the body is parsed successfully and the errorHandler is invoked when there is a parsing failure.

Usage:

jsonRequestBody @t errorHandler nextHandler

jsonRequestBody

Arguments

:: forall t h req. (Get h (JSONBody t) Request, ArrowChoice h)

=> h (Linked req Request, Text) Response

error handler

-> Middleware h req (JSONBody t ': req)

Same as jsonRequestBody' but with a media type application/json.

respondA

Arguments

:: forall body h. Sets h [Status, Body body, RequiredHeader "Content-Type" Text] Response

=> Status

Response status

-> MediaType

Media type of the response body

-> h body (Linked [RequiredHeader "Content-Type" Text, Body body, Status] Response)

A convenience arrow to generate a response specifying a status and body.

The "Content-Type" header will be set to the specified media type value.

respondJsonA

Arguments

:: forall body h. Sets h [Status, JSONBody body, RequiredHeader "Content-Type" Text] Response

=> Status

Response status

-> h body (Linked [RequiredHeader "Content-Type" Text, JSONBody body, Status] Response)

A convenience arrow to generate a response specifying a status and JSON body.

The "Content-Type" header will be set to "application/json".

respondJsonA'

Arguments

:: forall body h. Sets h [Status, JSONBody body, RequiredHeader "Content-Type" Text] Response

=> Status

Response status

-> MediaType

Media type of the response body

-> h body (Linked [RequiredHeader "Content-Type" Text, JSONBody body, Status] Response)

A convenience arrow to generate a response specifying a status and JSON body.

The "Content-Type" header will be set to the specified media type value.

setBody

Arguments

:: forall body a h ts. Sets h [Body body, RequiredHeader "Content-Type" Text] Response

=> MediaType

The media type of the response body

-> h a (Linked ts Response)

-> h (body, a) (Linked (RequiredHeader "Content-Type" Text ': (Body body ': ts)) Response)

Set the response body along with a media type.

The media type value is used to set the "Content-Type" header in the response.

setBodyWithoutContentType :: forall body a h ts. Set h (Body body) Response => h a (Linked ts Response) -> h (body, a) (Linked (Body body ': ts) Response)

Set the response body without specifying any media type.

setJSONBody :: forall body a h ts. Sets h [JSONBody body, RequiredHeader "Content-Type" Text] Response => h a (Linked ts Response) -> h (body, a) (Linked (RequiredHeader "Content-Type" Text ': (JSONBody body ': ts)) Response)

Set the response body to a JSON value.

The "Content-Type" header will be set to "application/json".

setJSONBodyWithoutContentType :: forall body a h ts. Set h (JSONBody body) Response => h a (Linked ts Response) -> h (body, a) (Linked (JSONBody body ': ts) Response)

Set the response body to a JSON value without specifying any media type.

setJSONBody'

Arguments

:: forall body a h ts. Sets h [JSONBody body, RequiredHeader "Content-Type" Text] Response

=> MediaType

The media type of the response body

-> h a (Linked ts Response)

-> h (body, a) (Linked (RequiredHeader "Content-Type" Text ': (JSONBody body ': ts)) Response)

Set the response body to a JSON value along with a media type.

The media type value is used to set the "Content-Type" header in the response.