Force No Default Selection in Selectinput()

R Shiny Set SelectizeInput default value as NULL

Try this one:

library(shiny)

fileNames = c('a', 'b', 'c', 'd', 'e')

ui <- fluidPage(
  selectInput("request","Select Existing Request",
                 choice = c('Choose a File Name' = '', unique(fileNames)), multiple = FALSE,
                 selected = NULL)
)

server <- function(input, output) {

}

shinyApp(ui = ui, server = server)

How to have default NULL value in Input & filter data only when non null value?

It worked when I made couple of changes .. not sure which one was the factor

1. Instead of null used other text i.e "No State selected" & applied condition on it:
2. changed dataframe name filtered_vaccine_center to filtered_vaccine

ui

selectInput(inputId = "vaccine_center_state_select",
                         label = "Select State to narrow your search", 
                         choices = c("No State selected",unique(vacc_centers$state))
                         ,selected = "No State selected" 
                         ,multiple = FALSE
             ),

server:

filtered_vaccine_centers <- reactive({
    
    req(input$vaccine_center_state_select)
    
    if(input$vaccine_center_state_select != "No State selected")
        
        {
            filtered_vaccine <- vacc_centers %>% 
                                filter(state == input$vaccine_center_state_select)
        
        }
    else filtered_vaccine <- vacc_centers
        
    
    }) %>% 
        bindCache(input$vaccine_center_state_select)

points of Vaccination Centers on lat, long axis without using country map coordinates

Output

Insert warning message from selectInput option

If you are open to using another package here is a shinyWidgets solution with a 'sendSweetAlert':

library(shinyWidgets)
library(shiny)

ui <- fluidPage(

  titlePanel("Old Faithful Geyser Data"),

  sidebarLayout(
    sidebarPanel(

      radioButtons(
        "filter1", 
        h3("Select properties"), 
        choiceValues = c(1, 2),
        choiceNames = list(
          tagList(
            tags$span("All properties"),
            tags$span(icon("info-circle"), id = "icon1", style = "color: blue;")
          ), 
          tagList(
            tags$span("Exclude properties"),
            tags$span(icon("info-circle"), id = "icon2", style = "color: blue;")
          )
        ),
        selected = 1
      ),

      selectInput("filter2", h3("Select farms"),
                  choices = list("All farms" = 1, 
                                 "Exclude farms" = 2),
                  selected = 1),
    ),

    mainPanel(

    )
  )
)

server <- function(input, output, session) {
  observe({
    if(input$filter2 == 2){
      sendSweetAlert(
        session = session,
        title = "Warning!",
        text = "Change filter options selected above",
        type = "warning"
      )
    }
  })
}

shinyApp(ui = ui, server = server)

All is needed is to observe the selectInput value and when the input is on "Exclude farms" which has a value of 2 a warning message is sent.

Datatable displays empy selectInput while values are selected by default

The words list is named:

> name <- c("Jack","Bob","Jack","Bob")
> item <- c("apple","olive","banana","tomato")
> d <- data.frame(name, item)
> 
> ( words <- tapply(d$item, d$name, I) )
$Bob
[1] olive  tomato
Levels: apple banana olive tomato

$Jack
[1] apple  banana
Levels: apple banana olive tomato

Therefore its JSON representation is:

> toJSON(words)
{"Bob":["olive","tomato"],"Jack":["apple","banana"]} 

This is not an array. Remove the names and you get the wanted array of arrays:

> toJSON(unname(words))
[["olive","tomato"],["apple","banana"]] 

Or instead of using 'jsonlite', use a basic JSON stringifier:

sprintf("[%s]", toString(vapply(words, function(x){
  sprintf("[%s]", toString(shQuote(x)))
}, character(1))))
# "[['olive', 'tomato'], ['apple', 'banana']]"

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