Update checkboxes from database after actionbutton is clicked in R shiny

Question

I'm creating a shiny app that will get values from a database table and update the other upon user request. The problem arises once the add button is clicked. The checkboxes hold the same value as earlier and do not get the new values from database.

ui <- fluidPage(

  checkboxGroupInput("inCheckboxGroup", "Available names", td),
  checkboxGroupInput("inCheckboxGroup2", "Present names",c(ch1,ch)),
  actionButton("action", label = "Add")
)

td, ch1 and ch are lists gathered from the database.

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

  # checkbox listener
  observe({
    x <- input$inCheckboxGroup
    y <- NULL

    if (is.null(x))
      x <- character(0)

    # Get the names for these ids
    for (i in x){
      y <- dbFetch(dbSendQuery(conn, paste0("--sql query--") ))
      z <- c(z,y[,1])
    }

    # Print the names from previous block into the checkboxes
    updateCheckboxGroupInput(session, "inCheckboxGroup2",
                             choices = c(ch1,z),
                             selected = z)
  })

  # button listener
  observeEvent(input$action,{
    for(i in input$inCheckboxGroup){
      rs <- dbSendQuery(conn, paste0("--sql query--"))
      dbFetch(rs)
    }
    showNotification("Row inserted")
  })
}

What I tried was to create a page refresh functionality or input reset that would do the trick. But even reloading the page does nothing. What would be the best approach for this?

Answer 1

You need to update the check boxes once the button is pushed so the updateCheckboxGroupInput needs to be in the observeEvent for the action button. Below is an example of how to do so.

library(shiny)

td<-c(1,2,3)
ch1<-c(1,2,3)
ch<-c(1,2,3)


ui <- fluidPage(
  checkboxGroupInput("inCheckboxGroup", "Available names", td),
  checkboxGroupInput("inCheckboxGroup2", "Present names",c(ch1,ch)),
  actionButton("action", label = "Add")
)

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

  # button listener
  observeEvent(input$action,{
    database<-c(4,5,6)
    updateCheckboxGroupInput(session,"inCheckboxGroup", choices = database)
    })

  }

shinyApp(ui, server)

If trying to update the values of the check boxes, do a similar command but used selected. Also below is how to update both sets of checkboxes.

  # button listener
  observeEvent(input$action,{
    database<-c(1,3)
    updateCheckboxGroupInput(session,"inCheckboxGroup", selected=database)
    #For the Second group simply call the other label
    updateCheckboxGroupInput(session,"inCheckboxGroup2", selected=database)
    })

 }