问题
my question is a followup question on the following discussion:
How to add/remove input fields dynamically by a button in shiny
I want a be able to add/remove dynamically input with action button on shiny app, but also when I add a new input I want the values of the input fields to remain instead of change as it is now. Can you help me with this?
For example if I change the first box and add another text input via the button, the value of the first box has been reset with the default one.
library(shiny)
ui <- shinyUI(fluidPage(
sidebarPanel(
actionButton("add_btn", "Add Textbox"),
actionButton("rm_btn", "Remove Textbox"),
textOutput("counter")
),
mainPanel(uiOutput("textbox_ui"))
))
server <- shinyServer(function(input, output, session) {
# Track the number of input boxes to render
counter <- reactiveValues(n = 0)
observeEvent(input$add_btn, {counter$n <- counter$n + 1})
observeEvent(input$rm_btn, {
if (counter$n > 0) counter$n <- counter$n - 1
})
output$counter <- renderPrint(print(counter$n))
textboxes <- reactive({
n <- counter$n
if (n > 0) {
lapply(seq_len(n), function(i) {
textInput(inputId = paste0("textin", i),
label = paste0("Textbox", i), value = "Hello World!")
})
}
})
output$textbox_ui <- renderUI({ textboxes() })
})
shinyApp(ui, server)
回答1:
There might be better solution but this also does the work.
library(shiny)
ui <- shinyUI(fluidPage(
sidebarPanel(
actionButton("add_btn", "Add Textbox"),
actionButton("rm_btn", "Remove Textbox"),
textOutput("counter")
),
mainPanel(uiOutput("textbox_ui"))
))
server <- shinyServer(function(input, output, session) {
# Track the number of input boxes to render
counter <- reactiveValues(n = 0)
#Track the number of input boxes previously
prevcount <-reactiveValues(n = 0)
observeEvent(input$add_btn, {
counter$n <- counter$n + 1
prevcount$n <- counter$n - 1})
observeEvent(input$rm_btn, {
if (counter$n > 0) {
counter$n <- counter$n - 1
prevcount$n <- counter$n + 1
}
})
output$counter <- renderPrint(print(counter$n))
textboxes <- reactive({
n <- counter$n
if (n > 0) {
# If the no. of textboxes previously where more than zero, then
#save the text inputs in those text boxes
if(prevcount$n > 0){
vals = c()
if(prevcount$n > n){
lesscnt <- n
isInc <- FALSE
}else{
lesscnt <- prevcount$n
isInc <- TRUE
}
for(i in 1:lesscnt){
inpid = paste0("textin",i)
vals[i] = input[[inpid]]
}
if(isInc){
vals <- c(vals, "New text box")
}
lapply(seq_len(n), function(i) {
textInput(inputId = paste0("textin", i),
label = paste0("Textbox", i), value = vals[i])
})
}else{
lapply(seq_len(n), function(i) {
textInput(inputId = paste0("textin", i),
label = paste0("Textbox", i), value = "New text box")
})
}
}
})
output$textbox_ui <- renderUI({ textboxes() })
})
shinyApp(ui, server)
Hope it helps!
来源：https://stackoverflow.com/questions/41233242/add-remove-input-fields-dynamically-by-a-button-in-shiny-and-keep-values