The session$clientdata object provides the server with some information about the client.
If the client is visiting a URL with a query string or hash (such as http://localhost:8100/?a=xxx&b=yyy#zzz), there will be values for url_search and url_hash_initial. This app will also display the parsed query string.
This app in the Shiny gallery is displayed without a query string. To see the query string, follow this link: http://gallery.shinyapps.io/client-data-and-query-string?a=xxx&b=yyy#zzz
| Type: Shiny | |
| Title: Client data and query string | |
| License: MIT | |
| Author: Winston Chang <[email protected]> | |
| AuthorUrl: http://www.rstudio.com/ | |
| Tags: clientdata query-string | |
| DisplayMode: Showcase |
| shinyServer(function(input, output, session) { | |
| # Print out clientData, which is a reactiveValues object. | |
| # This object is list-like, but it is not a list. | |
| output$summary <- renderText({ | |
| # Find the names of all the keys in clientData | |
| cnames <- names(session$clientData) | |
| # Apply a function to all keys, to get corresponding values | |
| allvalues <- lapply(cnames, function(name) { | |
| item <- session$clientData[[name]] | |
| if (is.list(item)) { | |
| list_to_string(item, name) | |
| } else { | |
| paste(name, item, sep=" = ") | |
| } | |
| }) | |
| paste(allvalues, collapse = "\n") | |
| }) | |
| # Parse the GET query string | |
| output$queryText <- renderText({ | |
| query <- parseQueryString(session$clientData$url_search) | |
| # Return a string with key-value pairs | |
| paste(names(query), query, sep = "=", collapse=", ") | |
| }) | |
| }) | |
| list_to_string <- function(obj, listname) { | |
| if (is.null(names(obj))) { | |
| paste(listname, "[[", seq_along(obj), "]] = ", obj, | |
| sep = "", collapse = "\n") | |
| } else { | |
| paste(listname, "$", names(obj), " = ", obj, | |
| sep = "", collapse = "\n") | |
| } | |
| } |
| shinyUI(fluidPage( | |
| titlePanel("Client data and query string example"), | |
| fluidRow( | |
| column(8, | |
| h3("session$clientdata values"), | |
| verbatimTextOutput("summary"), | |
| h3("Parsed URL query string"), | |
| verbatimTextOutput("queryText") | |
| ) | |
| ) | |
| )) |