R Shiny delete button into data table doesn't work well

Question

I have built a shiny App which allow user to update datatable whith a form. I have some trouble with a feature which allow user to delete a row in the datable by clicking on a actionLink into the rendered datatable.

It works properly but I manage some bug. When all the datatable where deleted once, and I put new entries the first new entries is non-deletable without deleted another row first.

To be clear here is the step to show the bug:

1. Add a text input and add it into the data table
2. Delete the input
3. Add a new text input
4. Try to delete it
5. Add another text input
6. Delete the second new input
7. Delete the first input

I don't understand why, I think it's come from the reactive values but I put observ event on the only two event possible to appear.

Here is a reproducible example to see the bug:

library(shiny)
library(DT)
library(shinydashboard)
library(shinyjs)



# ----- function which create the button into the table
shinyInput <- function(FUN, len, id, ...) {
  inputs <- len
  for (i in seq(len)) {
    inputs[i] <- as.character(FUN(paste0(id, len[i]), ...))
  }
  inputs
}

# ----- character form vector
fields<-c("text")


ui<-shinyUI(bootstrapPage(
  shinyjs::useShinyjs(),
  title = "Update form",
  fluidRow(
    sidebarPanel(width=2,
                 title = "Submit form", id = "submitTab", value = "submitTab",
                 textInput("text", "Text Input", ""),
                 actionButton("submit", "Add", class = "btn-primary",icon=icon("table"))
                 #     verbatimTextOutput("test")
    ),
    mainPanel(dataTableOutput("data_table")))

))

server<-shinyServer(function(input, output) {  
# ----- create the reactive value  
  v<-reactiveValues(data=NULL)  

# ----- when Add button is clicked
  observeEvent(input$submit, {
    dat <- sapply(fields, function(x) input[[x]])
    dat<-data.frame(t(dat),stringsAsFactors=F)
    if(!(is.null(v$data)) && (input$text%in%v$data$text==F)) {
      v$data <- rbind(v$data[,-2], dat)
    } else if(!is.null(v$data) && (input$text%in%v$data$text==T)) {
      indice<-which(v$data$text==input$text)
      v$data[indice,-2] <- dat
    } else {
      v$data<-dat
    }
    v$data<-data.frame(v$data[,-2],Delete = shinyInput(actionLink, rownames(v$data), 'button_',class="btn btn-delete",icon=icon("minus-circle"),label="",onclick = 'Shiny.onInputChange(\"select_button\",  this.id)' ))
  })

# ----- When Delete table button is clicked 
  observeEvent(input$select_button, {
    #     dat<-v$data
    selectedRow <- as.numeric(strsplit(input$select_button, "_")[[1]][2])    
    #     dat <- dat[rownames(dat) != selectedRow, ] 
    v$data<-v$data[rownames(v$data)!=selectedRow,]
    v$data<-data.frame(v$data[,-2],Delete = shinyInput(actionLink, rownames(v$data), 'button_',class="btn btn-delete",icon=icon("minus-circle"),label="",onclick = 'Shiny.onInputChange(\"select_button\",  this.id)' ))
  })

# ----- Render the data table
  output$data_table <- renderDataTable(server = TRUE,escape=F,extensions = 'TableTools',options = list(pageLength = 10),{
    if (is.null(v$data)) return()
    v$data
  })  
})

shinyApp(ui,server)

Answer 1

Hi I think the issue for step 4 is that the value of input$select_button have not changed, pasting the time at this.id seems to fixed it. Look at the code below (I've made some other change) :

library(shiny)
library(DT)
library(shinydashboard)
library(shinyjs)



# ----- function which create the button into the table
shinyInput <- function(FUN, len, id, ...) {
  inputs <- len
  for (i in seq(len)) {
    inputs[i] <- as.character(FUN(paste0(id, len[i]), ...))
  }
  inputs
}

# ----- character form vector
fields<-c("text")


ui<-shinyUI(bootstrapPage(
  shinyjs::useShinyjs(),
  title = "Update form",
  fluidRow(
    sidebarPanel(width=2,
                 title = "Submit form", id = "submitTab", value = "submitTab",
                 textInput("text", "Text Input", ""),
                 actionButton("submit", "Add", class = "btn-primary",icon=icon("table"))
                 #     verbatimTextOutput("test")
    ),
    mainPanel(dataTableOutput("data_table"), verbatimTextOutput("test")))

))

server<-shinyServer(function(input, output) {  
  # ----- create the reactive value  
  v<-reactiveValues(data=NULL)  

  # ----- when Add button is clicked
  observeEvent(input$submit, {
    dat <- sapply(fields, function(x) input[[x]])
    dat<-data.frame(V1 = dat,stringsAsFactors=F)
    if(!(is.null(v$data)) && (!input$text %in% v$data$text)) {
      v$data <- rbind(data.frame(V1 = as.character(v$data[,1])), dat)
      rownames(v$data) <- seq_len(nrow(v$data))
    } else if(!is.null(v$data) && (input$text %in% v$data$text)) {
      indice<-which(v$data$text==input$text)
      v$data[indice,-2] <- dat
    } else {
      v$data<-dat
    }
    v$data<-data.frame(V1 = v$data[,-2],
                       Delete = shinyInput(actionLink, 
                                       rownames(v$data), 
                                       'button_',
                                       class="btn btn-delete",
                                       icon=icon("minus-circle"),
                                       label="",
                                       onclick = 'Shiny.onInputChange(\"select_button\",  (this.id + \"@\" + Date()))' ))
  })

  # ----- When Delete table button is clicked 
  observeEvent(input$select_button, {
    #     dat<-v$data
    input_button <- gsub(pattern = "@.*", replacement = "", x = input$select_button)
    selectedRow <- as.numeric(strsplit(input_button, "_")[[1]][2])    
    #     dat <- dat[rownames(dat) != selectedRow, ] 
    v$data <- v$data[!rownames(v$data) %in% selectedRow,]
    if (nrow(v$data) > 0) {
      v$data<-data.frame(V1 = v$data[,-2],
                         Delete = shinyInput(actionLink,  
                                         rownames(v$data), 
                                         'button_',
                                         class="btn btn-delete",
                                         icon=icon("minus-circle"),
                                         label="",
                                         onclick = 'Shiny.onInputChange(\"select_button\",  (this.id + \"@\" + Date()))' ))
    }
  })
  output$test <- renderPrint({input$select_button})
  # ----- Render the data table
  output$data_table <- renderDataTable(server = TRUE,escape=F,extensions = 'TableTools',options = list(pageLength = 10),{
    if (is.null(v$data)) return()
    v$data
  })  
})

shinyApp(ui,server)