miniUI: dynamically create additional panels for miniTabstripPanel - r

Question

I want to create a Shiny gadget using miniUI which dynamically can add additional tabs to a miniTabstripPanel. However, no panels have shown up in my experiments when I try it using renderUI and uiOutput. I think it has to do with the height of the elements not being set correctly (by me).
Anyway, below is a minimal example. If I use the uiOutput() line, it does not work. If I instead comment that out and use the miniTabPanel() line directly, which is the exact code used in renderUI(), it works fine.
library(shiny)
library(miniUI)
TSTAddin <- function() {
panno <- 0
ui <- miniPage(
actionButton('btn_newPan', 'New Panel'),
miniTabstripPanel(
# miniTabPanel('pan1', miniContentPanel(height='100%', actionButton('Test','Test'))), miniTabPanel('pan2', miniContentPanel(height='100%', actionButton('Test','Test')))
uiOutput('panelset')
)
)
server <- function(input, output, session) {
output$panelset <- renderUI({
panno <<- panno+1
txt <- paste0("miniTabPanel('pan", 1:panno, "', miniContentPanel(height='100%', actionButton('Test','Test')))", collapse=", ")
list( eval(parse(text=txt)) )
})
}
viewer <- paneViewer(300)
runGadget(ui, server, viewer = viewer)
}
TSTAddin()
EDIT:
The code suggested by mkemp6 solves the problem. However, if I now include a button on the panel, only part of it is shown. How can one correct the size of the dynamically generated panels? An example adopting mkemp6's code follows.
library(shiny)
library(miniUI)
TSTAddin2 <- function() {
ui <- miniPage(
actionButton("nTabs", "More Tabs"),
actionButton("neg_nTabs", "Less Tabs"),
uiOutput('panelset')
)
server <- function(input, output, session) {
output$panelset <- renderUI({
n <- seq(max(input$nTabs - input$neg_nTabs + 1, 1))
miniTabList <- lapply(paste("Pan", n), function(x) miniTabPanel(x, actionButton('Test','Test')))
do.call(miniTabstripPanel, miniTabList)
})
}
viewer <- paneViewer(300)
runGadget(ui, server, viewer = viewer)
}
TSTAddin2()

Answer 1

Try this:
library(shiny)
library(miniUI)
TSTAddin <- function() {
ui <- miniPage(
actionButton("nTabs", "More Tabs"),
actionButton("neg_nTabs", "Less Tabs"),
uiOutput('panelset')
)
server <- function(input, output, session) {
output$panelset <- renderUI({
n <- seq(max(input$nTabs - input$neg_nTabs + 1, 1))
miniTabList <- lapply(paste("Pan", n), miniTabPanel)
do.call(miniTabstripPanel, miniTabList)
})
}
viewer <- paneViewer(300)
runGadget(ui, server, viewer = viewer)
}
TSTAddin()

Answer 2

Regarding your second issue with the size of the panels:
Whenever you use uiOutput(), shiny puts another div tag around the rendered content. As it appears, the style of this content is by default not compatible with the miniUI elements. However, this can be corrected by adding some specific CSS code (which I have basically copied from some other classes of miniUI.css).
Also, when you put several elements (in your case: action buttons) among each other within a miniContenPanel, it is advisable to create separate containers for each of them. You can easily do that using fillCol / fillRow as described in http://shiny.rstudio.com/articles/gadget-ui.html.
This code works with me (you may want to further improve the layout):
library(shiny)
library(miniUI)
TSTAddin2 <- function() {
ui <- miniPage(
tags$head(
tags$style(HTML("
.ui-output-mini {position: absolute;top:0;right:0;bottom:0;left:0;display:-webkit-flex;display:-ms-flexbox;display:flex;-webkit-flex-direction:column;-ms-flex-direction:column;flex-direction:column;}
"))
),
fillCol(flex=c(NA, NA, 1),
actionButton("nTabs", "More Tabs", width='100%'),
actionButton("neg_nTabs", "Less Tabs", width='100%'),
uiOutput('panelset', class='ui-output-mini')
)
)
server <- function(input, output, session) {
output$panelset <- renderUI({
n <- seq(max(input$nTabs - input$neg_nTabs + 1, 1))
miniTabList <- lapply(paste("Pan", n), function(x) miniTabPanel(x, actionButton('Test','Test')))
do.call(miniTabstripPanel, miniTabList)
})
}
viewer <- paneViewer(300)
runGadget(ui, server, viewer = viewer)
}
TSTAddin2()