Integrating the shinyStorePlus R package into Shiny applications

Introduction

Create a shiny app such that when a user refreshed the app, they can still see the input they entered.

Integrating the shinyStorePlus package into your already developed application is very simple and can be accomplished in just few lines of code. Neat, right?

Well, get started …

Step 1: An already working application

Below is the code for an application to which we will integrate the shinyStorePlus package


# library
library(shiny)

if(interactive()) {
ui <- fluidPage(
    # Application title
    titlePanel("shinyStorePlus by Obi Obianom"),

    # Sidebar with a slider input for number of bins
    sidebarLayout(
        sidebarPanel(
            sliderInput("bins",
                        "Number of bins:",
                        min = 1,
                        max = 50,
                        value = 30),
            selectizeInput(
              'foo', label = NULL, choices = state.name,
              options = list(create = TRUE),
              multiple = TRUE
            ),
           textInput("redd","What if I?",value = "Wayword...")
        ),

        # Show a plot of the generated distribution
        mainPanel(
            plotOutput("distPlot")
        )
    )
)

server <- function(input,output,session) {
  # make sure the  input, output, session arguments are present !IMPORTANT

    output$distPlot <- renderPlot({

        # generate bins based on input$bins from ui.R
        x    <- faithful[, 2]
        bins <- seq(min(x), max(x), length.out = input$bins + 1)

        # draw the histogram with the specified number of bins
        hist(x, breaks = bins, col = 'darkgray', border = 'white',
             xlab = 'Waiting time to next eruption (in mins)',
             main = 'Histogram of waiting times')

    })
}

shinyApp(ui = ui, server = server)
}

Step 2: Install and attach the shinyStorePlus R package

The shinyStorePlus package is available on CRAN and can be installed as shown below

install.packages(shinyStorePlus)

Attach library

library(shinyStorePlus)

Now, the code you have should look like this …


# library
library(shiny)
library(shinyStorePlus)

if(interactive()) {
ui <- fluidPage(
    # Application title
    titlePanel("shinyStorePlus by Obi Obianom"),

    # Sidebar with a slider input for number of bins
    sidebarLayout(
        sidebarPanel(
            sliderInput("bins",
                        "Number of bins:",
                        min = 1,
                        max = 50,
                        value = 30),
            selectizeInput(
              'foo', label = NULL, choices = state.name,
              options = list(create = TRUE),
              multiple = TRUE
            ),
           textInput("redd","What if I?",value = "Wayword...")
        ),

        # Show a plot of the generated distribution
        mainPanel(
            plotOutput("distPlot")
        )
    )
)

server <- function(input,output,session) {
  # make sure the  input, output, session arguments are present !IMPORTANT

    output$distPlot <- renderPlot({

        # generate bins based on input$bins from ui.R
        x    <- faithful[, 2]
        bins <- seq(min(x), max(x), length.out = input$bins + 1)

        # draw the histogram with the specified number of bins
        hist(x, breaks = bins, col = 'darkgray', border = 'white',
             xlab = 'Waiting time to next eruption (in mins)',
             main = 'Histogram of waiting times')

    })
}

shinyApp(ui = ui, server = server)
}

Step 3: Initialize by including the scripts required for processing the stores

You must initialize for the package to work. Its as simple as inserting the function below within the fluidPage()

initStore()

Now, the code you have should look like this …


# library
library(shiny)
library(shinyStorePlus)

if (interactive()) {
  ui <- fluidPage(
    # Initialize shinyStorePlus
    initStore(),

    # Application title
    titlePanel("shinyStorePlus by Obi Obianom"),

    # Sidebar with a slider input for number of bins
    sidebarLayout(
      sidebarPanel(
        sliderInput("bins",
          "Number of bins:",
          min = 1,
          max = 50,
          value = 30
        ),
        selectizeInput(
          "foo",
          label = NULL, choices = state.name,
          options = list(create = TRUE),
          multiple = TRUE
        ),
        textInput("redd", "What if I?", value = "Wayword...")
      ),

      # Show a plot of the generated distribution
      mainPanel(
        plotOutput("distPlot")
      )
    )
  )

  server <- function(input, output, session) {
    # make sure the  input, output, session arguments are present !IMPORTANT

    output$distPlot <- renderPlot({

      # generate bins based on input$bins from ui.R
      x <- faithful[, 2]
      bins <- seq(min(x), max(x), length.out = input$bins + 1)

      # draw the histogram with the specified number of bins
      hist(x,
        breaks = bins, col = "darkgray", border = "white",
        xlab = "Waiting time to next eruption (in mins)",
        main = "Histogram of waiting times"
      )
    })
  }

  shinyApp(ui = ui, server = server)
}

Step 4: Setup storage in the server function

Setup the stores by declaring a unique app id and including this in the setup function as shown below

appid = "applicatio32n501" setupStorage(appId = appid,inputs = TRUE)

Now, the code you have should look like this …


# library
library(shiny)
library(shinyStorePlus)

if (interactive()) {
  ui <- fluidPage(
    # Initialize shinyStorePlus
    initStore(),

    # Application title
    titlePanel("shinyStorePlus by Obi Obianom"),

    # Sidebar with a slider input for number of bins
    sidebarLayout(
      sidebarPanel(
        sliderInput("bins",
          "Number of bins:",
          min = 1,
          max = 50,
          value = 30
        ),
        selectizeInput(
          "foo",
          label = NULL, choices = state.name,
          options = list(create = TRUE),
          multiple = TRUE
        ),
        textInput("redd", "What if I?", value = "Wayword...")
      ),

      # Show a plot of the generated distribution
      mainPanel(
        plotOutput("distPlot")
      )
    )
  )

  server <- function(input, output, session) {
    # make sure the  input, output, session arguments are present !IMPORTANT

    output$distPlot <- renderPlot({

      # generate bins based on input$bins from ui.R
      x <- faithful[, 2]
      bins <- seq(min(x), max(x), length.out = input$bins + 1)

      # draw the histogram with the specified number of bins
      hist(x,
        breaks = bins, col = "darkgray", border = "white",
        xlab = "Waiting time to next eruption (in mins)",
        main = "Histogram of waiting times"
      )
    })

    # insert at the bottom  !!!IMPORTANT
    appid <- "applicatio32n501"
    setupStorage(appId = appid, inputs = TRUE)
  }

  shinyApp(ui = ui, server = server)
}

Step 5: Run the final code

Paste the final R code into your console and run. Change several inputs when the application loads, see the effect. Now, refresh the page. You should see that your previous inputs are preserved.