R闪亮：renderTable重置输入$ tableid_rows_selected值

Question

Background : I'm creating a simple table using the following code:

output$mytable = DT::renderDataTable({
              datatable(data_frame_object, selection='single')
              }) 

Note that selection='single' makes it so that only one row is shown as selected at a time. I track the row that is selected by the user by using the following code:

index=input$mytable_rows_selected

Problem : The problem I am having is that I want to reset the value of index=input$mytable_rows_selected every time a new row is selected. Currently, if user selects row 1, the index will have value [1]. If user then selects row 2, then index will have value of [1, 2]. However, I just want index to have value of [2].

Attempted solution: My workaround has been to use index[length(index)] to get the row that was last selected,but this is not suitable for my purposes.

Working example using iris data:

library(shiny)
library(DT)

server <- function(input, output, session) {

  output$mytable = DT::renderDataTable({
    datatable(iris[,c(1,4,5)],selection='single')
  }, 
  options = list(lengthMenu = c(5, 30, 50), pageLength = 10, orderClasses=TRUE)
  ) 

  output$info = DT::renderDataTable({

    index=input$mytable_rows_selected

    if (length(index)){
      index2=index[length(index)]
    }
    else{
      index2=index
    }
    iris[index2,c(1,4)]
  }, 
  options = list(pageLength = 5, orderClasses=TRUE, searching=FALSE)
  )

}

ui <- fluidPage(

  fluidRow(
    column(4,dataTableOutput('mytable')),

    column(6,offset=1,
           tabsetPanel(type="tabs", 
                       tabPanel("hi",dataTableOutput('info')))
    )   
  )
)

Answer 1

Try this code

library(shiny)
library(DT)

server <- function(input, output, session) {

  output$mytable = DT::renderDataTable({
    datatable(iris[,c(1,4,5)],selection='single')
  }, 
  options = list(lengthMenu = c(5, 30, 50), pageLength = 10, orderClasses=TRUE)
  ) 

  selected.rows <- reactiveValues(index = NULL)

  observe({
      selected.rows$index <- input$mytable_rows_selected
  })

  output$info = DT::renderDataTable({

    index=selected.rows$index

    if (length(index)){
      index2=index[length(index)]
    }
    else{
      index2=index
    }
    iris[index2,c(1,4)]
  }, 
  options = list(pageLength = 5, orderClasses=TRUE, searching=FALSE)
  )

}

ui <- fluidPage(

  fluidRow(
    column(4,dataTableOutput('mytable')),

    column(6,offset=1,
           tabsetPanel(type="tabs", 
                       tabPanel("hi",dataTableOutput('info')))
    )   
  )
)