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).
If value is TRUE and run in a hosting environment (Shiny
Server or Connect) with reconnections enabled, then when the session ends
due to the network connection closing, the client will attempt to
reconnect to the server. If a reconnection is successful, the browser will
send all the current input values to the new session on the server, and
the server will recalculate any outputs and send them back to the client.
If value is FALSE, reconnections will be disabled (this is
the default state). If "force", then the client browser will always
attempt to reconnect. The only reason to use "force" is for testing
on a local connection (without Shiny Server or Connect).
A reactiveValues() object that contains information about the client.
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 use
url_protocol, url_hostname, url_port,
url_pathname, url_search, url_hash_initial
and url_hash 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. The
url_search value may be used with parseQueryString()
to access query string parameters.
clientData also contains information about each output.
output_outputId_width and output_outputId_height
give the dimensions (using offsetWidth and offsetHeight) of
the DOM element that is bound to outputId, and
output_outputId_hidden is a logical that indicates whether
the element is hidden. These values may be NULL if the output is
not bound.
The session's input object (the same as is passed into the Shiny
server function as an argument).
A function that returns TRUE if the client has
disconnected.
Server-side version of ns <- NS(id). If bare IDs need to be
explicitly namespaced for the current module, session$ns("name")
will return the fully-qualified ID.
Synonym for onSessionEnded.
Registers a function to be called before the next time (if once=TRUE)
or every time (if once=FALSE) Shiny flushes the reactive system.
Returns a function that can be called with no arguments to cancel the
registration.
Registers a function to be called after the next time (if once=TRUE)
or every time (if once=FALSE) Shiny flushes the reactive system.
Returns a function that can be called with no arguments to cancel the
registration.
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.
The session's output object (the same as is passed into the Shiny
server function as an argument).
For internal use.
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 into
registerDataObj) and req (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 of filterFunc should be a Rook-style
response.
The equivalent of hitting the browser's Reload button. Only works if the session is actually connected.
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).
An environment for app authors and module/package authors to store whatever session-specific data they want.
User's log-in information. Useful for identifying users on hosted platforms such as RStudio Connect and Shiny Server.
The user's relevant group information. Useful for determining what
privileges the user should or shouldn't have.
Resets/clears the brush with the given brushId, if it exists on
any imageOutput or plotOutput in the app.
Sends a custom message to the web page. type must be a
single-element character vector giving the type of message, while
message can be any jsonlite-encodable value. Custom messages
have no meaning to Shiny itself; they are used solely to convey information
to custom JavaScript logic in the browser. You can do this by adding
JavaScript code to the browser that calls
Shiny.addCustomMessageHandler(type, function(message){...})
as the page loads; the function you provide to
addCustomMessageHandler will be invoked each time
sendCustomMessage is called on the server.
Similar to sendCustomMessage, but the message must be a raw vector
and the registration method on the client is
Shiny.addBinaryMessageHandler(type, function(message){...}). The
message argument on the client will be a
DataView.
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 like
updateTextInput().
Set input names to be excluded from bookmarking.
Returns the set of input names to be excluded from bookmarking.
Registers a function that will be called just before bookmarking state.
Registers a function that will be called just after bookmarking state.
Registers a function that will be called when a session is restored, before all other reactives, observers, and render functions are run.
Registers a function that will be called when a session is restored, after all other reactives, observers, and render functions are run.
Do bookmarking and invoke the onBookmark and onBookmarked callback functions.
Registers expressions for export in test mode, available at the test snapshot URL.
Returns a URL for the test snapshots. Only has an effect when the
shiny.testmode option is set to TRUE. For the input, output, and
export arguments, TRUE means to return all of these values. It is also
possible to specify by name which values to return by providing a
character vector, as in input=c("x", "y"). The format can be
"rds" or "json".
Sets the current bootstrapLib() theme, which updates the value of
getCurrentTheme(), invalidates session$getCurrentTheme(), and calls
function(s) registered with registerThemeDependency() with provided
theme. If those function calls return htmltools::htmlDependency()s with
stylesheets, then those stylesheets are "refreshed" (i.e., the new
stylesheets are inserted on the page and the old ones are disabled and
removed).
A reactive read of the current bootstrapLib() theme.