如何解决如何在仆人中使用 Reqbody 接收 POST
下面的代码应该能够发送一个json主体。 但我总是收到以下请求的错误:
curl -X POST -i http://localhost:8080/comTrade --data 'name=nut&age=12'
错误信息是:
Status Code: 405 Method Not Allowed
content-type: text/plain
date: Fri,12 Mar 2021 18:49:04 GMT
server: Warp/3.3.14
transfer-encoding: chunked
data User = User {
age :: Int,name :: String
} deriving Generic
instance FromJSON User where
parseJSON = withObject "User" parseUser
parseUser :: Object -> Parser User
parseUser o = do
n <- (o .: "name")
a <- (o .: "age")
return (User a n)
instance ToJSON User where
toJSON user = object
[ "age" .= age user,"name" .= name user
]
type ComTradeAPI =
"comTrade" :> ReqBody '[JSON] User :> Post '[JSON] Int
:<|> "test" :> Get '[JSON] User
:<|> Raw
myServer :: Server ComTradeAPI
myServer = getUser
:<|> test
:<|> serveDirectoryWebApp "site"
where
test :: Handler User
test = return (User 12 "nut")
getUser :: User -> Handler Int
getUser usr = return 12
main :: IO ()
main = openbrowser "http://localhost:8080/index.html"
>> run 8080 (serve (Proxy :: Proxy ComTradeAPI) myServer)
谁能告诉我如何让servant-server接收POST消息?
解决方法
正如 Fyodor Soikin 在评论中指出的那样,OP 中的 cURL 示例不发布 JSON,而是发布 URL 编码的数据。如果您对 cURL 使用 -v
(verbose) 选项而不是 -i
,您可以看到这一点:
$ curl -v http://localhost:8080/comtrade -d "{ \"name\": \"nut\",\"age\": 12 }"
* Trying ::1:8080...
* TCP_NODELAY set
* Trying 127.0.0.1:8080...
* TCP_NODELAY set
* Connected to localhost (127.0.0.1) port 8080 (#0)
> POST /comtrade HTTP/1.1
> Host: localhost:8080
> User-Agent: curl/7.67.0
> Accept: */*
> Content-Length: 28
> Content-Type: application/x-www-form-urlencoded
>
* upload completely sent off: 28 out of 28 bytes
* Mark bundle as not supporting multiuse
< HTTP/1.1 405 Method Not Allowed
< Transfer-Encoding: chunked
< Date: Sat,13 Mar 2021 12:52:59 GMT
< Server: Warp/3.2.28
< Content-Type: text/plain
<
Only GET or HEAD is supported
请注意,Content-Type
是 application/x-www-form-urlencoded
。
ReqBody '[JSON] User
类型声明 API 期望主体为 JSON。然后,您需要做的第一件事是发布 JSON 而不是 URL 编码的数据。
然而,这本身还不够:
$ curl -v http://localhost:8080/comtrade -d "{ \"name\": \"nut\",13 Mar 2021 12:56:42 GMT
< Server: Warp/3.2.28
< Content-Type: text/plain
<
Only GET or HEAD is supported
请注意,cURL 仍然默认 Content-Type
为 application/x-www-form-urlencoded
。由于 API 被声明为接收 JSON,因此您必须明确告诉它这里是 JSON:
$ curl -i http://localhost:8080/comtrade -H "Content-Type: application/json" -d "{ \"name\": \"nut\",\"age\": 12 }"
HTTP/1.1 200 OK
Transfer-Encoding: chunked
Date: Sat,13 Mar 2021 12:58:09 GMT
Server: Warp/3.2.28
Content-Type: application/json;charset=utf-8
12
据我所知,Haskell 代码没有任何问题。这是一个正确使用HTTP协议的问题。
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