Shiny R renderPrint in loop usinf RenderUI only update the output - r

Question

I am trying to dynamically render multiple text output from multiple text input. I tried to use this very helpfull example and this one too.
This conversation is also helpfull.
But when I try to adapt this examples on the following script, I have a problem of output update. Apparently, only the last element was read and updated. It's probably a reactivity problem but it seems to be difficult to associate reactive{()} and renderUI{()}functions.
rm(list = ls())
library(shiny)
creatDataElem <- function(ne, input) {
x1 <- lapply(1:ne, function(i) {
textInput(paste0("elemName", i),
label = h4(strong("Name of dataset element")),
value = "")
})
return(x1)
}
ui = (fluidPage(
sidebarLayout(
sidebarPanel(
sliderInput("elemNb",
"Number of elements", value = 1, min = 1,
max = 3)
,
conditionalPanel(
condition = "input.elemNb == 1",
creatDataElem(1)
),
conditionalPanel(
condition = "input.elemNb == 2",
creatDataElem(2)
),
conditionalPanel(
condition = "input.elemNb == 3",
creatDataElem(3)
)
),
mainPanel(
uiOutput("nameElem")
)
)
)
)
server = function(input, output, session) {
max_elem <- 3
# Name
output$nameElem <-renderUI({
nameElem_output_list <- lapply(1:input$elemNb, function(i) {
elemName <- paste0("elemName", i)
tags$div(class = "group-output",
verbatimTextOutput(elemName)
)
})
do.call(tagList, nameElem_output_list)
})
for (i in 1:max_elem) {
local({
force(i)
my_i <- i
elemName <- paste0("elemName", my_i)
output[[elemName]] <- renderPrint(input[[elemName]])
})
}
}
runApp(list(ui = ui, server = server))
The idea with a reactive({}) function is to add an independant object (a function in this case) like:
nameElem <- reactive({
if (input$goElem == 0) {
return()
} else {
isolate({
if (is.null(input$elemName)) {
return()
} else if (test(input$elemName)) {
return("TEST RESULT")
} else {
return(input$elemName)
}
})
}
})
and to use renderUI on this object (with an ActionButton).
So, if someone knows why the output does not return the good object...

Answer 1

I think one of your problems is that your creatDataElem function is such that when it is called with argument ne=3, the first and second textInput elements are created again (and their value "lost").
Anyway, I think one solution would be to create those textInput elements as an "uiOutput".
You'll find a possible solution below which (I think) does what you want.
Lise
rm(list = ls())
library(shiny)
ui = (fluidPage(
sidebarLayout(
sidebarPanel(
sliderInput("elemNb",
"Number of elements", value = 1, min = 1,
max = 3),
uiOutput("myUI")
),
mainPanel(
uiOutput("nameElem")
)
)
)
)
server = function(input, output, session) {
output$myUI=renderUI({
w=""
for (i in 1:input$elemNb){
w=paste0(w,
textInput(paste0("elemName",i),label='Name of dataset element'))
}
HTML(w)
})
output$nameElem <-renderUI({
elems=c("<div>")
for(i in 1:input$elemNb){
elems=paste(elems,"</div><div>",input[[paste0("elemName",i)]])
}
elems=paste0(elems,"</div>")
HTML(elems)
})
}
runApp(list(ui = ui, server = server))

Answer 2

Found a solution:
library(readr)
library(dplyr)
library(shiny)
df <- data.frame(symbol = 1:10)
uiOutput("myUI")
createUI <- function(dfID, symbol) {
div(class="flex-box",paste0(symbol, " - 10"))
}
output$myUI <- renderUI({
w <- lapply(seq_len(nrow(df)), function(i) {
createUI(i, df[i,"symbol"])
})
do.call(fluidPage,w)
})