A resource which streams the data from a local file. More...

#include <Wt/WFileResource.h>

Inheritance diagram for Wt::WFileResource:

Public Member Functions
	WFileResource ()
	Default constructor. More...

	WFileResource (const std::string &fileName)
	Creates a new resource for a file. More...

	WFileResource (const std::string &mimeType, const std::string &fileName)
	Creates a new resource with given mime-type for a file.

	~WFileResource ()
	Destructor. More...

void	setFileName (const std::string &fileName)
	Sets a (different) filename. More...

const std::string &	fileName () const
	Returns the filename.

virtual void	handleRequest (const Http::Request &request, Http::Response &response) override
	Handles a request. More...

Public Member Functions inherited from Wt::WStreamResource
	WStreamResource ()
	Default constructor. More...

	WStreamResource (const std::string &mimeType)
	Creates a new resource with given mime-type.

	~WStreamResource ()
	Destructor. More...

void	setMimeType (const std::string &mimeType)
	Sets the mime-type.

const std::string &	mimeType () const
	Returns the mime-type.

void	setBufferSize (int size)
	Configures the buffer size. More...

int	bufferSize () const
	Returns the buffer size. More...

Public Member Functions inherited from Wt::WResource
	WResource ()
	Creates a new resource.

	~WResource ()
	Destroys the resource. More...

void	suggestFileName (const Wt::WString &name, ContentDisposition disposition=ContentDisposition::Attachment)
	Suggests a filename to the user for the data streamed by this resource. More...

const Wt::WString &	suggestedFileName () const
	Returns the suggested file name. More...

void	setDispositionType (ContentDisposition cd)
	Configures the Content-Disposition header. More...

ContentDisposition	dispositionType () const
	Returns the currently configured content disposition. More...

void	setChanged ()
	Generates a new URL for this resource and emits the changed signal. More...

void	setInvalidAfterChanged (bool enabled)
	Return "page not found" for prior resource URLs after change. More...

bool	invalidAfterChanged () const
	Should "page not found" be returned for outdated resource URLs. More...

void	setInternalPath (const std::string &path)
	Sets an internal path for this resource. More...

std::string	internalPath () const
	Returns the internal path. More...

const std::string &	generateUrl ()
	Generates an URL for this resource. More...

const std::string &	url () const
	Returns the current URL for this resource. More...

Signal &	dataChanged ()
	Signal emitted when the data presented in this resource has changed. More...

void	setUploadProgress (bool enabled)
	Indicate interest in upload progress. More...

Signal< ::uint64_t, ::uint64_t > &	dataReceived ()
	Signal emitted when data has been received for this resource. More...

void	write (std::ostream &out, const Http::ParameterMap &parameters=Http::ParameterMap(), const Http::UploadedFileMap &files=Http::UploadedFileMap())
	Stream the resource to a stream. More...

virtual void	handleAbort (const Http::Request &request)
	Handles a continued request being aborted. More...

void	haveMoreData ()
	Indicate that more data is available. More...

void	setTakesUpdateLock (bool enabled)
	Set whether this resource takes the WApplication's update lock. More...

bool	takesUpdateLock () const
	Returns whether this resources takes the WApplication's update lock. More...

Public Member Functions inherited from Wt::WObject
void	addChild (std::unique_ptr< WObject > child)
	Add a child WObject whose lifetime is determined by this WObject.

template<typename Child >
Child *	addChild (std::unique_ptr< Child > child)
	Add a child WObject, returning a raw pointer. More...

std::unique_ptr< WObject >	removeChild (WObject *child)
	Remove a child WObject, so its lifetime is no longer determined by this WObject.

template<typename Child >
std::unique_ptr< Child >	removeChild (Child *child)
	Remove a child WObject, so its lifetime is no longer determined by this WObject. More...

virtual const std::string	id () const
	Returns the (unique) identifier for this object. More...

virtual void	setObjectName (const std::string &name)
	Sets an object name. More...

virtual std::string	objectName () const
	Returns the object name. More...

void	resetLearnedSlots ()
	Resets learned stateless slot implementations. More...

template<class T >
void	resetLearnedSlot (void(T::*method)())
	Resets a learned stateless slot implementation. More...

template<class T >
WStatelessSlot *	implementStateless (void(T::*method)())
	Declares a slot to be stateless and learn client-side behaviour on first invocation. More...

template<class T >
WStatelessSlot *	implementStateless (void(T::method)(), void(T::undoMethod)())
	Declares a slot to be stateless and learn client-side behaviour in advance. More...

void	isNotStateless ()
	Marks the current function as not stateless. More...

template<class T >
WStatelessSlot *	implementJavaScript (void(T::*method)(), const std::string &jsCode)
	Provides a JavaScript implementation for a method. More...

Public Member Functions inherited from Wt::Core::observable
	observable () noexcept
	Default constructor.

virtual	~observable ()
	Destructor. More...

template<typename... Args, typename C >
auto	bindSafe (void(C::*method)(Args...)) noexcept
	Protects a method call against object destruction. More...

template<typename... Args, typename C >
auto	bindSafe (void(C::*method)(Args...) const) const noexcept
	Protects a const method call against object destruction. More...

template<typename Function >
auto	bindSafe (const Function &function) noexcept
	Protects a function against object destruction. More...

Additional Inherited Members
Public Types inherited from Wt::WObject
typedef void(WObject::*	Method) ()
	Typedef for a WObject method without arguments.

Protected Member Functions inherited from Wt::WStreamResource
void	handleRequestPiecewise (const Http::Request &request, Http::Response &response, std::istream &input)
	Handles a request and streams the data from a std::istream. More...

Protected Member Functions inherited from Wt::WResource
void	beingDeleted ()
	Prepares the resource for deletion. More...

Protected Member Functions inherited from Wt::WObject
virtual WStatelessSlot *	getStateless (Method method)
	On-demand stateless slot implementation. More...

Detailed Description

A resource which streams the data from a local file.

To update the resource, either use setFileName() to point it to a new file, or emit the WResource::dataChanged() signal when only the file contents has changed, but not the filename.

The resource makes use of continuations to transmit data piecewise, without blocking a thread or requiring the entire file to be read in memory. The size of the buffer can be changed using setBufferSize().

Usage examples:

auto csvFile = std::make_unique<Wt::WFileResource>("text/csv", "/opt/files/afile.csv");
csvFile->suggestFileName("data.csv");
auto anchor = std::make_unique<Wt::WAnchor>(csvFile.get(), "CSV data");
 
auto imageFile = std::make_unique<Wt::WFileResource>("image/png", "/opt/files/image.png");
imageFile->suggestFileName("data.png");
auto image = std::make_unique<Wt::WImage>(imageFile.get(), "PNG version");

See also: WStreamResource, WMemoryResource

Constructor & Destructor Documentation

◆ WFileResource() [1/2]

Wt::WFileResource::WFileResource ( )

Default constructor.

You need to set a file name (and mime type) for the resource using setFileName() and setMimeType().

◆ WFileResource() [2/2]

Wt::WFileResource::WFileResource ( const std::string & fileName )

Creates a new resource for a file.

The mime type defaults to "text/plain".

◆ ~WFileResource()

Wt::WFileResource::~WFileResource ( )

Destructor.

It is up to the user to make sure that the resource is no longer in use (by e.g. a WImage).

Member Function Documentation

◆ handleRequest()

void Wt::WFileResource::handleRequest	(	const Http::Request &	request,
		Http::Response &	response
	)

overridevirtual

Handles a request.

You may want to specialize this function to compute the file on the fly. However, you need to take into account the fact that the WFileResource implementation may use continuations to split the download in smaller chunks. Your implementation should thus look like:

void handleRequest(const Http::Request& request,
                   Http::Response& response) {
  if (!request.continuation()) {
    ... prepare data
    setFileName(myTmpFile);
  }
 
  WFileResource::handleRequest(request, response);
}

Implements Wt::WResource.

◆ setFileName()

void Wt::WFileResource::setFileName ( const std::string & fileName )

Sets a (different) filename.

Set the location of the file on the local filesystem which must be streamed for this resource.

Public Member Functions

Additional Inherited Members