How do I get the data from the selected rows of a filtered datatable (DT)?

Question

The DT package allows you to get the indices of selected rows using input$tableID_rows_selected. This works great for tables that do not have filtered data. How

Answer 1

While the accepted answer gives a working solution for shiny, it wasn't obvious how to implement it inside an R Markdown document with flexdashboard.

In Rmd documents, render*() functions like DT::renderDataTable() are usually used anonymously, but it is possible to explicitly assign them to output slots in shiny. In this case, to use the input$tableID_rows_selected construct, it's necessary to do so.

This solution also sorts the index to always maintain the same order as in the original data frame.

---
title: "MRE"
author: ""
output: 
  flexdashboard::flex_dashboard:
    orientation: columns
    vertical_layout: scroll
runtime: shiny
---

Page {data-orientation=columns}
=======================================================================

Column {data-width=650}
-----------------------------------------------------------------------

### .

```{r}
  require(DT)
  library(dplyr)
  library(tibble)

  sliderInput("filter", label = "Filter by cyl", min = 4, max = 8, step = 2, value = 6)


  filteredTable_data <- reactive({
    mtcars %>% rownames_to_column() %>%  ##dplyr's awkward way to preserve rownames
          filter(., cyl == input$filter) %>% column_to_rownames()
  })

  ##explicit assignment to output ID
  DT::dataTableOutput("filteredTable")
  output$filteredTable <- DT::renderDataTable({
    datatable(
      filteredTable_data(),
      selection = list(mode = "multiple"),
      caption = "Filtered Table (based on cyl)"
    )
  })

  filteredTable_selected <- reactive({
    ids <- input$filteredTable_rows_selected
    filteredTable_data()[sort(ids),]  ##sort index to ensure orig df sorting
  })

  ##anonymous
  DT::renderDataTable({
    datatable(
      filteredTable_selected(),
      selection = list(mode = "none"),
      caption = "Table that gets data from unfiltered original data"
    )
  })

```

And here's how the output looks like: