Document a shiny application

Is there any way to generate documentation for a R shiny application?

It becomes very hard to maintain a shiny application without documentation.

It seems that all the eco-system of tests/documentation is created for an R package structure. Maybe we can emulate/extend this behavior for a shiny application?

An example :

A reactive expression is typically an R shiny element taht can contain complex data structure.

   filtered_dat <- reactive({ 
      dx[ NAME == input$crr & TOU == input$tou & 
            PlotYear == input$year. & PlotMonth == input$season]
    })

To give more context, I am here in the context of building a complete web application using R shiny. All the business-logic is wrapped in a separated package(s).

For testing Ui I think it is complicated ( one can use Rselenium for example) , but generating doc from roxygen2 comments is just parsing. It should be easy to have such tool.

Solution

update

Add an example of shiny application

There is not an ideal solution but this is basically what I am doing to deal with my shiny applications to create a robust and well "documented" shiny application:

Create a package where you put all your logic within it. Don't worry to call input/output structure from the package as an argument. Also try to create some controls within your package. For example you can have an inline version of some basic shiny controls.

A typical package will have this structure:

 R
     ui-view1.R
     ui-view2.R
     server-server1.R
     server-server2.R
     controls.R

Create a shiny application that is structured in a way that reflects your different applications elements. Basically create a view/server files for each app page. You can of course put the shiny application under inst/ui or put it in a separate project.

Here an example:

 app 
     ui.R
     server.R
     global.R
     views
        view1.R
        view2.R
     servers
        server1.R
        server2.R
     init 
        global1.R
        gloabl2.R