Initialize rv$all_ui

On the application the reactiveValues rv is initialized as below:

rv <- reactiveValues(all_ui = list())

Dynamic call through observeEvent

Every time a dataset is loaded (eg: data_mod1$trigger increments) the observeEvent:

callModule(
    module = data_info,
    id = data_mod1$trigger,
    data = data_mod1$data,
    data_name = data_mod1$data_name
)

rv$all_ui[[data_mod1$trigger]] <- data_infoUI(id = data_mod1$trigger)

Render UI elements

Note that the UI element returned by the module is a shinyWidgets::panel. Thus, we can use it in a simple tagList function.

output$all_results <- renderUI({
    tagList(rv$all_ui)
})

Variables initialization

trick     <- reactiveVal(0)
res       <- list()
obs_close <- list()

• The reactiveVal trick is an integer that incremente every time the user call the module merge_modules. It is used as an id for the tabPanel and for list res names.
• The list res contains each server logic return of modules merge_modules.
• The list obs_close contains observers that trigger to close a tabPanel.

Dynamic call through observeEvent

Every time a dataset is loaded (eg: data_mod1$trigger increments) the observeEvent:

res[[paste(id)]] <<- callModule(
    module = merge_modules,
    id = id,
    data = data,
    name = name
)

appendTab(
    inputId = "all_tabs",
    tabPanel(
        title = tabTitle(name, id),
        value = id,
        tags$br(),
        merge_modulesUI(id = id)
    ),
    select = TRUE
)

obs_close[[paste(id)]] <<- observe({
    shinyjs::onclick(id = paste0("close", id), closeTab(id = id))
})

trick(trick() + 1)

The reactiveVal trick is used to trigger an update in the renderUI ui_summary because the list res isn’t reactive itself !

Use server outputs in application

You can use the list res elsewhere in your application. However don’t forget to reference the trick reactiveVal to be sure your reactive context updates.

# Summary of all opened tabs
output$ui_summary <- renderUI({
    # Reference trick to update reactive context
    fool <- trick()
    
    zz <- lapply(res, reactiveValuesToList)

    if (length(zz) == 0) {
        content <- div(class = "warn ", "No variable loaded")
    } else {
        # Use output of module merge_modules:
        #  - name
        #  - nb_funs
        content <- tags$ul(
          lapply(zz, function(x) {
            tags$li(paste(x$name, ":", x$nb_funs))
          })
        )
    }

    tagList(content)
})

Bonus: Close a tabPanel

In our example we can “revert” a dynamic module call. To do so, we need to undo what’s done in the previous chapter:

• Remove a tabPanel (UI part).
• Remove related element from list res (Server part).

This 2 steps are part of the function closeTab described below. This function is called in the observe created dynamically (eg previous chapter):

closeTab <- function(id) {
    # Remove tab from UI
    removeTab(inputId = "all_tabs", target = paste(id))
    
    # Remove related element from list
    res[[paste(id)]] <<- NULL
    
    # Increase trick to refresh output$ui_summary
    trick(trick() + 1)
}

Note that the cross “button” inside the tabPanel title is created with function below:

# Function to add a cross after tabPanel title
tabTitle <- function(name, id) {
    tags$span(
        name, HTML(" "),
        tags$span(
            id = paste0("close", id),
            class = "close",
            HTML("×")
        )
    )
}