Showcase - extended example for Tree

[jan-smo]

[Proposal]
to add to showcase / doc

ui <- function(id) {​
  ns <- NS(id)
  tagList(
    reactOutput(ns("tree")),
    htmlOutput(ns("info"))
  )
}

server <- function(id) {​
  moduleServer(id, function(input, output, session) {​
    ns <- session$ns 
    treeReactive <- reactiveVal(treeList)
    observeEvent(input$expand, {​
      treeReactive(
        modifyTree(treeReactive(), ids = input$expand$id, props = list(isExpanded = TRUE))
      )
    })

    observeEvent(input$collapse, {​
      treeReactive(
        modifyTree(treeReactive(), ids = input$collapse$id, props = list(isExpanded = FALSE))
      )
    })

    output$tree <- renderReact({​
      Tree(
        contents = treeReactive(),
        onNodeExpand = setInput(ns("expand")),
        onNodeCollapse = setInput(ns("collapse")),
        onNodeClick = setInput(ns("click"))
      )
    })

    select_node <- reactive({​
      input$click$id
    })

    expand_node <- reactive({​
      input$expand$id
    })   

    collapse_node <- reactive({​
      input$collapse$id
    })

     output$info <- renderText({​
      paste0("Expanded: ", expand_node(), "<br>",
             "Collapsed: ", collapse_node(), "<br>",
             "Selected: ", select_node())
    })
  })
}