Happstack.Server.Validation

Support for validating server output on-the-fly. Validators can be configured on a per content-type basis.

Documentation

setValidator :: (Response -> IO Response) -> Response -> Response

Set the validator which should be used for this particular Response when validation is enabled.

Calling this function does not enable validation. That can only be done by enabling the validation in the Conf that is passed to simpleHTTP.

You do not need to call this function if the validator set in Conf does what you want already.

Example: (use noopValidator instead of the default supplied by validateConf)

simpleHTTP validateConf $ ok . setValidator noopValidator =<< htmlPage

See also: validateConf, wdgHTMLValidator, noopValidator, lazyProcValidator.

setValidatorSP :: (Monad m, ToMessage r) => (Response -> IO Response) -> m r -> m Response

ServerPart version of setValidator.

Example: (Set validator to noopValidator)

 simpleHTTP validateConf $ setValidatorSP noopValidator (dir "ajax" ... )

validateConf :: Conf

Extend nullConf by enabling validation and setting wdgHTMLValidator as the default validator for text/html.

Example:

simpleHTTP validateConf . anyRequest $ ok htmlPage

runValidator :: (Response -> IO Response) -> Response -> IO Response

Actually perform the validation on a Response.

Run the validator specified in the Response. If none is provide use the supplied default instead.

Note: This function will run validation unconditionally. You probably want setValidator or validateConf.

wdgHTMLValidator :: (MonadIO m, ToMessage r) => r -> m Response

Validate text/html content with WDG HTML Validator.

This function expects the executable to be named validate and it must be in the default PATH.

See also: setValidator, validateConf, lazyProcValidator.

noopValidator :: Response -> IO Response

A validator which always succeeds.

Useful for selectively disabling validation. For example, if you are sending down HTML fragments to an AJAX application and the default validator only understands complete documents.

lazyProcValidator

Arguments

:: FilePath

name of executable

-> [String]

arguments to pass to the executable

-> Maybe FilePath

optional path to working directory

-> Maybe [(String, String)]

optional environment (otherwise inherit)

-> (Maybe ByteString -> Bool)

content-type filter

-> Response

Response to validate

-> IO Response

Validate the Response using an external application.

If the external application returns 0, the original response is returned unmodified. If the external application returns non-zero, a Response containing the error messages and original response body is returned instead.

This function also takes a predicate filter which is applied to the content-type of the response. The filter will only be applied if the predicate returns true.

NOTE: This function requires the use of -threaded to avoid blocking. However, you probably need that for Happstack anyway.

See also: wdgHTMLValidator.