Add values to a reactive table in shiny

Question

I want users of my shiny app to be able to add elements to a table iteratively, but I can\'t work out how to hold the values.

In this example, I want the user to be

Answer 1

I think you want to use reactiveValues() to store your data frame. Here is a possible solution:

library(shiny)

runApp(list(
  ui=pageWithSidebar(headerPanel("Adding entries to table"),
                 sidebarPanel(textInput("text1", "Column 1"),
                              textInput("text2", "Column 2"),
                              actionButton("update", "Update Table")),
                 mainPanel(tableOutput("table1"))),
server=function(input, output, session) {
values <- reactiveValues()
values$df <- data.frame(Column1 = NA, Column2 = NA)
newEntry <- observe({
  if(input$update > 0) {
    newLine <- isolate(c(input$text1, input$text2))
    isolate(values$df <- rbind(values$df, newLine))
  }
})
output$table1 <- renderTable({values$df})
}))

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Edit

To avoid creating an empty row, create an empty data.frame rather than one with NA:

values$df <- data.frame(Column1 = numeric(0), Column2 = numeric(0))

And indexing seems better for adding the rows than rbind() (which messes up the column names... not sure why):

isolate(values$df[nrow(values$df) + 1,] <- c(input$text1, input$text2))