session
Value
- clientData
-
A
reactiveValues
object that contains information about the client.allowDataUriScheme
is a logical value that indicates whether the browser is able to handle URIs that use thedata:
scheme.pixelratio
reports the "device pixel ratio" from the web browser, or 1 if none is reported. The value is 2 for Apple Retina displays.singletons
- for internal useurl_protocol
,url_hostname
,url_port
,url_pathname
,url_search
, andurl_hash_initial
can be used to get the components of the URL that was requested by the browser to load the Shiny app page. These values are from the browser's perspective, so neither HTTP proxies nor Shiny Server will affect these values. Theurl_search
value may be used withparseQueryString
to access query string parameters.
clientData
also contains information about each output.output_outputId_width
andoutput_outputId_height
give the dimensions (usingoffsetWidth
andoffsetHeight
) of the DOM element that is bound tooutputId
, andoutput_outputId_hidden
is a logical that indicates whether the element is hidden. These values may beNULL
if the output is not bound. - input
-
The session's
input
object (the same as is passed into the Shiny server function as an argument). - isClosed()
- A function that returns
TRUE
if the client has disconnected. - onEnded(callback)
-
Synonym for
onSessionEnded
. - onFlush(func, once=TRUE)
-
Registers a function to be called before the next time (if
once=TRUE
) or every time (ifonce=FALSE
) Shiny flushes the reactive system. Returns a function that can be called with no arguments to cancel the registration. - onFlushed(func, once=TRUE)
-
Registers a function to be called after the next time (if
once=TRUE
) or every time (ifonce=FALSE
) Shiny flushes the reactive system. Returns a function that can be called with no arguments to cancel the registration. - onSessionEnded(callback)
- Registers a function to be called after the client has disconnected. Returns a function that can be called with no arguments to cancel the registration.
- output
-
The session's
output
object (the same as is passed into the Shiny server function as an argument). - reactlog
- For internal use.
- registerDataObj(name, data, filterFunc)
-
Publishes any R object as a URL endpoint that is unique to this session.
name
must be a single element character vector; it will be used to form part of the URL.filterFunc
must be a function that takes two arguments:data
(the value that was passed intoregisterDataObj
) andreq
(an environment that implements the Rook specification for HTTP requests).filterFunc
will be called with these values whenever an HTTP request is made to the URL endpoint. The return value offilterFunc
should be a Rook-style response. - request
- An environment that implements the Rook specification for HTTP requests. This is the request that was used to initiate the websocket connection (as opposed to the request that downloaded the web page for the app).
- sendCustomMessage(type, message)
-
Sends a custom message to the web page.
type
must be a single-element character vector giving the type of message, whilemessage
can be any jsonlite-encodable value. Custom messages have no meaning to Shiny itself; they are used soley to convey information to custom JavaScript logic in the browser. You can do this by adding JavaScript code to the browser that callsShiny.addCustomMessageHandler(type, function(message){...})
as the page loads; the function you provide toaddCustomMessageHandler
will be invoked each timesendCustomMessage
is called on the server. - sendInputMessage(inputId, message)
-
Sends a message to an input on the session's client web page; if the input
is present and bound on the page at the time the message is received, then
the input binding object's
receiveMessage(el, message)
method will be called.sendInputMessage
should generally not be called directly from Shiny apps, but through friendlier wrapper functions likeupdateTextInput
.
Description
Shiny server functions can optionally include session
as a parameter
(e.g. function(input, output, session)
). The session object is an
environment that can be used to access information and functionality
relating to the session. The following list describes the items available
in the environment; they can be accessed using the $
operator (for
example, session$clientData$url_search
).