Shiny 1.0.1

Breaking changes

We unintentionally introduced a minor breaking change in that checkboxGroupInput used to accept choices = NULL to create an empty input. With Shiny 1.0.1, this throws an error; using choices = character(0) works. We intend to eliminate this breakage in Shiny 1.0.2.

Update (4/20/2017): This has now been fixed in Shiny 1.0.2, currently available on CRAN.

Also, the selected argument for radioButtons, checkboxGroupInput, and selectInput once upon a time accepted the name of a choice, instead of the value of a choice; this behavior has been deprecated with a warning for several years now, and in Shiny 1.0.1 it is no longer supported at all.

Storing single reactive values with reactiveVal

The reactiveValues object has been a part of Shiny since the earliest betas. It acts like a reactive version of an environment or named list, in that you can store and retrieve values using names:

rv <- reactiveValues(clicks = 0)

observeEvent(input$button, {
 currentValue <- rv$clicks
 rv$clicks <- currentValue + 1
})

If you only have a single value to store, though, it’s a little awkward that you have to use a data structure designed for multiple values.

With the new reactiveVal function, you can now create a reactive object for a single variable:

clicks <- reactiveVal(0)

observeEvent(input$button, {
 currentValue <- clicks()
 clicks(currentValue + 1)
})

As you can see in this example, you can read the value by calling it like a function with no arguments; and you set the value by calling it with one argument.

This has the added benefit that you can easily pass the clicks object to another function or module (no need to wrap it in a reactive()).

More flexible radioButtons and checkboxGroupInput

It’s now possible to create radio button and checkbox inputs with arbitrary HTML as labels. To do so, however, you need to pass different arguments to the functions. Now, when creating (or updating) either of radioButtons() or checkboxGroupInput(), you can specify the options in one of two (mutually exclusive) ways:

• What we’ve always had: Use the choices argument, which must be a vector or list. The names of each element are displayed in the app UI as labels (i.e. what the user sees in your app), and the values are used for computation (i.e. the value is what’s returned by input$rd, where rd is a radioButtons() input). If the vector (or list) is unnamed, the values provided are used for both the UI labels and the server values.

• What’s new and allows HTML: Use both the choiceNames and the choiceValues arguments, each of which must be an unnamed vector or list (and both must have the same length). The elements in choiceValues must still be plain text (these are the values used for computation). But the elements in choiceNames (the UI labels) can be constructed out of HTML, either using the HTML() function, or an HTML tag generation function, like tags$img() and icon().

Here’s an example app that demos the new functionality (in this case, we have a checkboxGroupInput() whose labels include the flag of the country they correspond to):

ggplot2 > 2.2.1 compatibility

The development version of ggplot2 has some changes that break compatibility with earlier versions of Shiny. The fixes in Shiny 1.0.1 will allow it to work with any version of ggplot2.

A note on Shiny v1.0.0

In January of this year, we quietly released Shiny 1.0.0 to CRAN. A lot of work went into that release, but other than minor bug fixes and features, it was mostly laying the foundation for some important features that will arrive in the coming months. So if you’re wondering if you missed the blog post for Shiny 1.0.0, you didn’t.

Full changes

As always, you can view the full changelog for Shiny 1.0.1 (and 1.0.0!) in our NEWS.md file.