Communicating with ShinyItemAnalysis App

You might have already noticed that both the UI and server logic functions in the source code of your SIA module have a special imports argument. While being set to NULL by default, once your module package is installed and the SIA app is run1, the imports argument is actually populated with a multitude of objects that SIA app exports for your module. From the module’s perspective, these form a list of imported objects, hence the name “imports”. This vignette explains the nature of imports, how to use them in your module, and how to communicate with the app to get the most out of the module-app alliance that SIA modules offer.

Objects imported from SIA

Every single object defined in the SIA app that inherits from reactive, reactiveVal or reactivevalues is relayed to the imports list available from within the module’s server function2.

reactives and reactiveVals

To use reactives and single reactive values, you have to “call” them. There is no difference from usual shiny conventions.

Refer to the source code of ShinyItemAnalysis app for the names of the objects and server logic context, and/or possibly use browser() from within your module’s server function and inspect imports object by yourself3. It is also possible to put cat(names(imports), sep = "\n") in your module’s function to get the object names listed in your console. However, we recommend to stick with the former, as you can inspect the imports interactively from R console, save them, and then possibly reuse in preview mode4, keeping the development cycle short.

inputs and reactiveValues

All SIA’s inputs are relayed to the same imports object described above. In your module, you’ll find them in imports$input.

For instance, to get the name of currently picked toy dataset in the app, you would use imports$input$data_toydata as your usual input.

The idea is the same for reactivevalues, as input in fact inherits from reactivevalues. To use reactive values, you simply use them by their name, as you would do in ordinary shiny code.

Advanced: Updating SIA’s inputs

In case you want to update input values living outside your module, it gets a bit trickier. You have to obtain the correct session object first, which is reliably done by subsetting the parent session from your module’ current session. This code would set the toy dataset to “CZmaturaS”:

parent_session <- .subset2(session, "parent")

updateSelectInput(
  session = parent_session,
  inputId = "data_toydata",
  selected = "CZmaturaS_ShinyItemAnalysis"
)

The chunk above would be placed in your regular observer, possibly bounded to some actionButton press or any other event with bindEvent. Note that if you use shiny modules inside a SIA module, you have to get the correct session object for SIA, which could possibly be “grandparent” or higher from your SIA module’s module perspective.

  1. Using ShinyItemAnalysis::run_app() function.↩︎

  2. Actually, UI function of a module possesses its imports as well, but the SIA app doesn’t provide any yet, as we are currently unsure what to relay in an UI part.↩︎

  3. Note again you have to build and install your module package first and run it within the SIA app to see the imports.↩︎

  4. However, you have to shiny::isolate() any reactive expression first to store the actual object in a regular non-reactive one. Then, you are expected to wrap the result in a simple function that returns the object, so it plays nicely with the module’s code that works with reactive expressions in imports.↩︎