module IHP.Controller.NotFound
( notFoundWhen
, notFoundUnless
, handleNotFound
, buildNotFoundResponse
, renderNotFound
)
where
import IHP.Prelude hiding (displayException)
import IHP.Controller.RequestContext
import Network.HTTP.Types (status404)
import Network.Wai
import Network.HTTP.Types.Header
import qualified Text.Blaze.Html.Renderer.Utf8 as Blaze
import qualified Data.ByteString.Lazy as LBS
import IHP.HSX.QQ (hsx)
import qualified System.Directory as Directory
import IHP.Controller.Context
import IHP.Controller.Response (respondAndExit)
-- | Stops the action execution with a not found message (404) when the access condition is True.
--
-- __Example:__ Checking a user is the author of a blog post.
--
-- > action EditPostAction { postId } = do
-- > post <- fetch postId
-- > notFoundWhen (post.authorId /= currentUserId)
-- >
-- > renderHtml EditView { .. }
--
-- This will throw an error and prevent the view from being rendered when the current user is not the author of the post.
notFoundWhen :: (?context :: ControllerContext) => Bool -> IO ()
notFoundWhen condition = when condition renderNotFound
-- | Stops the action execution with a not found message (404) when the access condition is False.
--
-- __Example:__ Checking a user is the author of a blog post.
--
-- > action EditPostAction { postId } = do
-- > post <- fetch postId
-- > notFoundUnless (post.authorId == currentUserId)
-- >
-- > renderHtml EditView { .. }
--
-- This will throw an error and prevent the view from being rendered when the current user is not the author of the post.
notFoundUnless :: (?context :: ControllerContext) => Bool -> IO ()
notFoundUnless condition = unless condition renderNotFound
-- | Renders a 404 not found response. If a static/404.html exists, that is rendered instead of the IHP not found page
handleNotFound :: Request -> Respond -> IO ResponseReceived
handleNotFound request respond = do
response <- buildNotFoundResponse
respond response
buildNotFoundResponse :: IO Response
buildNotFoundResponse = do
hasCustomNotFound <- Directory.doesFileExist "static/404.html"
if hasCustomNotFound
then customNotFoundResponse
else pure defaultNotFoundResponse
-- | The default IHP 404 not found page
defaultNotFoundResponse :: Response
defaultNotFoundResponse = responseBuilder status404 [(hContentType, "text/html")] $ Blaze.renderHtmlBuilder [hsx|
Action not found
Error 404
Action not found
|]
-- | Renders the static/404.html file
customNotFoundResponse :: IO Response
customNotFoundResponse = do
-- We cannot use responseFile here as responseFile ignore the status code by default
--
-- See https://github.com/yesodweb/wai/issues/644
page <- LBS.readFile "static/404.html"
pure $ responseLBS status404 [(hContentType, "text/html")] page
-- | Renders an "Not found" page.
--
-- This can be useful e.g. when an entity cannot be accessed:
--
-- > action ExampleAction = do
-- > renderNotFound
--
-- You can override the default access denied page by creating a new file at @static/403.html@. Then IHP will render that HTML file instead of displaying the default IHP access denied page.
--
renderNotFound :: (?context :: ControllerContext) => IO ()
renderNotFound = do
response <- buildNotFoundResponse
respondAndExit response