Can I pass parameters to a shiny app via URL?

[merrittr]

I have a shiny app
https://merrittr.shinyapps.io/hydroshiny/

that starts off with 2 default parameters and then below alows the user to change these parameters via a side panel. Ideally for this application I would like to link to this app from a map that would have an href and a link that would provide the app the input$z and input$y

https://merrittr.shinyapps.io/hydroshiny/?y=05EF001&z=WaterLevel

is that possible?

output$lineplot <- renderPlot({
        subds <- subset(skdat, ID == input$z)
        subds$datetime <- as.POSIXct(subds$Date, format = "%Y-%m-%dT%H:%M:%OS")
        ggplot(subds, aes(x = datetime, y = !!as.name(input$y))) +
        geom_line()
})

My other motivation is to be able to get rid of that sidebar so the graph is bigger

[andresrcs]

You'd have to update the input inside the app when initializes. You would use the session$clientData$url_search variable to get the query parameters.

This is a simple reproducible example, that would work with this type of url https://merrittr.shinyapps.io/example-app/?bins=1

library(shiny)

ui <- fluidPage(

    titlePanel("Old Faithful Geyser Data"),

    sidebarLayout(
        sidebarPanel(
            sliderInput("bins",
                        "Number of bins:",
                        min = 1,
                        max = 50,
                        value = 30)
        ),

        mainPanel(
           plotOutput("distPlot")
        )
    )
)

server <- function(input, output, session) {
    # Here you read the URL parameter from session$clientData$url_search
    observe({
        query <- parseQueryString(session$clientData$url_search)
        if (!is.null(query[['bins']])) {
            updateSliderInput(session, "bins", value = query[['bins']])
        }
    })
    
    output$distPlot <- renderPlot({
        x    <- faithful[, 2]
        bins <- seq(min(x), max(x), length.out = input$bins + 1)

        hist(x, breaks = bins, col = 'darkgray', border = 'white')
    })
}

# Run the application 
shinyApp(ui = ui, server = server)

You can modify this to make it work with a reactive value for example and get rid of the controls.

[merrittr]

HA! that is great! thanks again Andres!

[cderv]

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