How to use reactiveValues() in order to store changes in a shiny app

问题

I have a simple shiny app in which I use a numericInput() to set the number of the rows of the dataframe.Then I use a selectInput() "Label" to select a Label from the datatable and then change its name with textInput() "Change to". The problem is that every time I try to change the name of a new Label using the textInput() the previous Label that I modified returns to default name. I believe this is happening because my DF is created inside a reactive function and cannot accept the subsetting. What I probably need is using reactiveValues() in order to store the previous values but I do not know exactly how to use it so I use reactive() here in order to display a working example.

library(shiny)
library(DT)

ui <- navbarPage(
  "Application",
  tabPanel("General",
           sidebarLayout(
             sidebarPanel(
               uiOutput("tex2"),
               uiOutput("book3"),
               uiOutput("book6")
             ),
             mainPanel(
               DT::dataTableOutput("hot3")
             )
           )))
#server.r
server <- function(input, output,session) {



  output$tex2<-renderUI({
    numericInput("text2", "#tests", value = 1, min=1)
  })

  output$book3<-renderUI({
    selectInput("bk3", "Label",  choices=(paste("Test",1:input$text2)))
  })

  output$book6<-renderUI({
    textInput("bk6", "Change to", value=NULL)
  })
  rt4<-reactive({
    DF <- data.frame(
      Test=paste(1:input$text2),
      Label=paste("Test",1:input$text2),
      stringsAsFactors = FALSE)
    if(!is.null(input$bk6) && input$bk6!=""){
      DF[DF$Label==isolate(input$bk3), "Label"] <- input$bk6
    }
    {
    DF
    }

  })

  output$hot3 <-DT::renderDataTable(
    rt4(),
    rownames= FALSE

  )
}

回答1:

This seems to work

library(shiny)
library(DT)
library(dplyr)

ui <- navbarPage(
  "Application",
  tabPanel("General",
           sidebarLayout(
             sidebarPanel(
               uiOutput("tex2"),
               uiOutput("book3"),
               uiOutput("book6"),
               actionButton('submit','submit')

             ),
             mainPanel(
               DT::dataTableOutput("hot3")
             )
           )))

server <- function(input, output,session) {

  output$tex2<-renderUI({
    numericInput("text2", "#tests", value = 1, min=1)
  })

  output$book3<-renderUI({
    selectInput("bk3", "Label",  choices=(paste("Test",1:input$text2)) )
  })

  output$book6<-renderUI({
    textInput("bk6", "Change to", value=NULL)
  })

  values <- reactiveValues(rv = NULL)

observe( { req(input$text2)
  Test <-paste(1: input$text2)
  Label <- paste("Test",1:input$text2)
         values$rv<-data.frame( Test= Test, Label=Label, stringsAsFactors = FALSE)}
        )

  observeEvent(input$submit,{

    if(!is.null(input$bk6) && input$bk6!=""){
          values$rv  <- values$rv %>%
             mutate(Label= ifelse(Label== input$bk3,input$bk6,Label))
    }
  })

  output$hot3 <-DT::renderDataTable( {
     datatable(values$rv, rownames=FALSE)
    })

}

shinyApp(ui,server)

回答2:

If you store your dataframe in reactiveValues object, you can update the data according to the inputs e.g. like that:

library(shiny)
library(DT)

ui <- navbarPage(
  "Application",
  tabPanel("General",
           sidebarLayout(
             sidebarPanel(
               uiOutput("tex2"),
               uiOutput("book3"),
               uiOutput("book6")
             ),
             mainPanel(
               DT::dataTableOutput("hot3")
             )
           )))
#server.r
server <- function(input, output,session) {



  output$tex2<-renderUI({
    numericInput("text2", "#tests", value = 1, min=1)
  })

 # update selectinput reactiveValues change
  output$book3<-renderUI({
    selectInput("bk3", "Label",  choices=rtdf4$DF[, 'Label'])
  })

  output$book6<-renderUI({
    textInput("bk6", "Change to", value=NULL)
  })

  rtdf4 <- reactiveValues()

 # fill reactiveValues based on the numberinput
  observe({
    if (is.null(input$text2)){
      rtdf4$DF <- data.frame(
        Test=paste(1),
        Label=paste("Test",1),
        stringsAsFactors = FALSE
      )
    } else {
      rtdf4$DF <- data.frame(
      Test=paste(1:input$text2),
      Label=paste("Test",1:input$text2),
      stringsAsFactors = FALSE
      )
    }

  })

  rt4 <- reactive({
    if (is.null(rtdf4$DF))
      return(NULL)

    if(!is.null(input$bk6) && input$bk6!=""){
      rtdf4$DF[rtdf4$DF$Label==isolate(input$bk3), "Label"] <- input$bk6
    }
    {
      rtdf4$DF
    }

  })

  output$hot3 <-DT::renderDataTable(
    rt4(),
    rownames= FALSE

  )
}

shinyApp(ui,server)

来源：https://stackoverflow.com/questions/51981821/how-to-use-reactivevalues-in-order-to-store-changes-in-a-shiny-app

标签

Shiny

reactive