How to use query parameters in Shiny

问题

I have two user groups in a DB. I want to query the DB to show a checkboxGroup in a Shiny app, with only one of the groups, depending on a URL query parameter.

For example, with a URL query parameters like this:

http://127.0.0.1:4014/?groupId=1

ideally, I would like to get that groupId value and use it to filter the user group:

res <- dbSendQuery(con, paste('SELECT user_id, user_name
        FROM   info i , enrolment e 
        WHERE  i.user_id = e.fk_user_id 
        AND    e.fk_group_id = ', groupId))
dataf <- dbFetch(res)
userlist <- as.list(setNames(dataf$user_id, dataf$user_name))

and then show the content of that userlist within Shiny, as a checkboxGroup, like so:

ui <- fluidPage( column(3, checkboxGroupInput("users", 
                                label = h3("User Names"), 
                                choices = userlist)))

Is it possible to pass such URL query parameters -as groupId in my example- to a Shiny app? (My code is working OK if I hard-code the groupId)

回答1:

http://shiny.rstudio.com/articles/client-data.html

Here's what you're looking for:

groupId <- parseQueryString(session$clientData$url_search)

Just remember to add

shinyServer(function(input, output, session)

It can look something like this at the end of the day:

ui <- bootstrapPage(
  h3("groupId"),
  verbatimTextOutput("queryText")
)

server <- function(input, output, session) {
  output$queryText <- renderText({
    query <- parseQueryString(session$clientData$url_search)
    paste(query, sep = "", collapse=", ")
  })
}

shinyApp(ui = ui, server = server)

Looking at your gist, you need to put your database objects/variables in the server part.

server(function(input, output, session) {
  source("keys.R")
  con <- dbConnect( MySQL(), user=login, password=pass, db=database, host=host)

Next, still in the server part, I would put, in either a observer or reactive expression, your dbGetQuery combined with the groupId parameter, and store the output.

This way you can apply that output to a checkboxGroupInput in the UI.

来源：https://stackoverflow.com/questions/35784667/how-to-use-query-parameters-in-shiny

标签

Shiny