How to stop recreating a dataset at each rendering of a shiny app

I have a simple shiny app in which 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 I want the application to keep all the name changes I make and not returning to the default name when I choose another Label. I think the problem is that the DF exists only within rt4 function and not outside it so it's recreated at each rendering.

#ui.r
navbarPage(
"Application",
tabPanel("General",
sidebarLayout(

sidebarPanel(
uiOutput("book3"),
uiOutput("book6")
),
mainPanel(

DT::dataTableOutput("hot3")

)
)))
#server.r
library(shiny)
library(DT)
server <- function(input, output,session)



output$book3<-renderUI(
selectInput("bk3",
"Label",
choices=(paste("Test",1:5)))
)

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

rt4<-reactive(input$bk6=="")
DF=data.frame(
Test=paste(1:5),
Label=paste("Test",1:5),
stringsAsFactors = FALSE)

else
DF[DF==input$bk3]<-input$bk6

DF

)

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

)




1 Answer
1

Important changes:

- as you expected, DF is defined once, in the server, see shiny scoping rules

- use <<- to modify the global (server) DF

- use isolate() to react only to the change of input$bk6

DF

<<-

DF

isolate()

input$bk6

library(shiny)
library(DT)

ui <- navbarPage(
"Application",
tabPanel("General",
sidebarLayout(
sidebarPanel(
uiOutput("book3"),
uiOutput("book6")
),
mainPanel(
DT::dataTableOutput("hot3")
)
)))

server <- function(input, output,session)

DF <- data.frame(
Test=paste(1:5),
Label=paste("Test",1:5),
stringsAsFactors = FALSE)

output$book3<-renderUI(
selectInput("bk3", "Label", choices=(paste("Test",1:5)))
)

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

rt4<-reactive(
if(!is.null(input$bk6) && input$bk6!="")
DF[DF$Label==isolate(input$bk3), "Test"] <<- input$bk6

DF
)

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

)


shinyApp(ui, server)


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