Defaults and Hiding Controls

Two closely related arguments — defaults and hide.inputs/hide.tabs — let you control what users see and what the module starts with. This vignette covers both in depth.

`defaults`: pre-filling inputs

Pass a named list to the defaults argument of any *InputsUI() call. Each name is an input ID (matching the underlying plot function argument), and its value is what the control initialises to.

library(VizModules)

ui <- fluidPage(
    sidebarLayout(
        sidebarPanel(
            dittoViz_scatterPlotInputsUI(
                "p", mtcars,
                defaults = list(
                    x.by        = "wt",
                    y.by        = "mpg",
                    color.by    = "cyl",
                    size        = 3,
                    best.fit    = TRUE
                )
            )
        ),
        mainPanel(dittoViz_scatterPlotOutputUI("p"))
    )
)

server <- function(input, output, session) {
    dittoViz_scatterPlotServer("p", data = reactive(mtcars))
}

shinyApp(ui, server)

Finding valid keys

Defaults keys map directly to the argument names of the underlying plot function. The quickest way to find them is the module’s *InputsUI() help page, e.g. ?dittoViz_scatterPlotInputsUI. The Plot parameters and defaults section lists every wired argument, its UI label, and its built-in default.

For inputs that come from the uniform tab helpers (Axes, Legend, Lines, Plotly), see ?uniform_axes_inputs_ui, ?uniform_legend_inputs_ui, ?uniform_lines_inputs_ui, and ?uniform_plotly_inputs_ui respectively.

Validation

get_default() (used internally by every module) accepts an optional validator predicate. If the value you supply fails validation — e.g. passing a string where a logical is expected — the module silently falls back to its built-in default rather than erroring. This means a typo in a key is silent; double-check key names against the help page if a default appears to have no effect.

Passing defaults through `createModuleApp()` and `*App()`

defaults is forwarded all the way through the app factory:

plotthis_BoxPlotApp(
    defaults = list(
        x.by     = "Species",
        y.by     = "Sepal.Length",
        pt.size  = 0
    )
)

The same defaults list is accepted by createModuleApp() directly:

app <- createModuleApp(
    inputs_ui_fn = plotthis_BoxPlotInputsUI,
    output_ui_fn = plotthis_BoxPlotOutputUI,
    server_fn    = plotthis_BoxPlotServer,
    data_list    = list("iris" = iris),
    defaults     = list(x.by = "Species", y.by = "Sepal.Length")
)
if (interactive()) runApp(app)

`hide.inputs`: hiding individual controls

Pass a character vector of input IDs to hide.inputs on the server function. Those controls are hidden from the UI while their values are still initialised (from defaults if supplied, otherwise the built-in default) and passed to the plot on every render.

server <- function(input, output, session) {
    dittoViz_scatterPlotServer(
        "p",
        data        = reactive(mtcars),
        hide.inputs = c("shape.by", "plot.order", "opacity")
    )
}

Hidden inputs reflow: the surrounding controls close the gap rather than leaving an empty space. This is handled automatically by the flexbox grid that organize_inputs() creates.

Use case: app-level fixed parameters

A common pattern is to fix a column mapping or aesthetic so that app users cannot change it, while still applying it to every plot:

server <- function(input, output, session) {
    dittoViz_scatterPlotServer(
        "p",
        data        = reactive(mtcars),
        defaults    = list(color.by = "cyl"),
        hide.inputs = "color.by"
    )
}

The colour mapping is always cyl, and the control for it never appears.

`hide.tabs`: hiding entire tab panels

Modules organise their inputs into named tabs (e.g. "Data", "Points", "Lines", "Axes", "Legend", "Plotly"). Pass a character vector of tab names to hide.tabs to remove whole groups at once.

server <- function(input, output, session) {
    dittoViz_scatterPlotServer(
        "p",
        data      = reactive(mtcars),
        hide.tabs = c("Plotly", "Lines", "Trajectory")
    )
}

All inputs in a hidden tab are still initialised and active — they just aren’t shown. This is useful when you want to keep the defaults for an entire feature group (e.g. plotly export settings) without exposing the controls to users.

Available tab names

Tab names are module-specific. Inspect the inputs list inside the relevant *InputsUI() source, or open ?<module>InputsUI and look for the tab headings described there. Common tabs across most modules include:

Tab	Contents
`"Data"`	Column selectors (x, y, color, split, etc.)
`"Axes"`	Title font, gridlines, tick styling
`"Legend"`	Legend title and text sizes
`"Lines"`	Reference lines (h/v/ablines)
`"Plotly"`	Download format, margins, drawn shape styling
`"Facet"`	Facet rows/columns, scales, subplot spacing

Combining `defaults`, `hide.inputs`, and `hide.tabs`

These three arguments compose freely. A typical production pattern is to set defaults for everything the user shouldn’t touch, hide the individual controls that need fine-grained locking, and hide any whole tabs that are irrelevant for your use case:

ui <- fluidPage(
    sidebarLayout(
        sidebarPanel(
            plotthis_ViolinPlotInputsUI(
                "v", example_rnaseq,
                defaults = list(
                    x.by     = "condition",
                    y.by     = "expression",
                    color.by = "condition"
                )
            )
        ),
        mainPanel(plotthis_ViolinPlotOutputUI("v"))
    )
)

server <- function(input, output, session) {
    plotthis_ViolinPlotServer(
        "v",
        data        = reactive(example_rnaseq),
        hide.inputs = c("color.by"),
        hide.tabs   = c("Plotly", "Lines")
    )
}

shinyApp(ui, server)

Here color.by is fixed to "condition" and hidden. The entire "Plotly" and "Lines" tabs are removed because they aren’t relevant to this app.

Using `hide.inputs` in `createModuleApp()` and `*App()`

Both accept hide.inputs and hide.tabs, forwarding them to the server if it supports those arguments:

plotthis_ViolinPlotApp(
    defaults    = list(x.by = "Species", y.by = "Sepal.Length"),
    hide.inputs = "color.by",
    hide.tabs   = "Plotly"
)

Hiding inputs dynamically in a custom module

When building a wrapper module (see vignette("custom-modules", package = "VizModules")), you can hide and show inputs at runtime in response to other inputs using shinyjs:

library(shinyjs)

myModuleServer <- function(id, data_reactive) {
    moduleServer(id, function(input, output, session) {
        # Hide the 'size' input whenever a size.by column is chosen
        observe({
            if (nzchar(input$size.by)) {
                shinyjs::hide(id = "size")
            } else {
                shinyjs::show(id = "size")
            }
        })
    })

    dittoViz_scatterPlotServer(id, data_reactive)
}

Note that shinyjs::hide() / shinyjs::show() act on the input element itself. For the reflow behaviour (no empty gap), use the internal .hide_input() / .show_input() helpers instead, which target the wrapping cell in the flexbox grid:

myModuleServer <- function(id, data_reactive) {
    moduleServer(id, function(input, output, session) {
        observe({
            if (nzchar(input$size.by)) {
                VizModules:::.hide_input(session, "size")
            } else {
                VizModules:::.show_input(session, "size")
            }
        })
    })

    dittoViz_scatterPlotServer(id, data_reactive)
}

defaults: pre-filling inputs

Finding valid keys

Validation

Passing defaults through createModuleApp() and *App()

hide.inputs: hiding individual controls