[英]shiny: updateSelectInput for a module UI (after insertUI)
[英]In Shiny I want to updateSelectInput() only once during UI load
我有一个下拉列表(SelectInput),我只想更新一次,并在上传UI时以编程方式将其加载到项目列表中。 我将其放在Render函数中,但问题是它一次又一次地重置。
selectInput
具有允许您设置初始状态的参数。 在这些参数中,你可以使用choices
提供选项,并selected
具有默认值。 请运行?shiny::selectInput
了解更多详细信息。
如果要在响应上下文中用户交互时对其进行更新,则在server
端呈现它或最好使用updateSelectInput
呈现将updateSelectInput
。
这是一个最小的示例:
library(shiny)
ui <- fluidPage(
selectInput(
inputId = "digits_input",
label = "Digits:",
choices = 0:9
## other arguments with default values:
# selected = NULL,
# multiple = FALSE,
# selectize = TRUE,
# width = NULL,
# size = NULL
),
selectInput(
inputId = "letters_input",
label = "Lower case letters:",
choices = letters,
selected = c("a", "b", "c"), # initially selected items
multiple = T # to be able to select multiple items
),
actionButton(
inputId = "update",
label = "Capitalize"
)
)
server <- function(session, input, output) {
observeEvent(input$update, {
updateSelectInput(
session,
inputId = "letters_input",
label = "Upper case letters:",
choices = LETTERS,
selected = c("A", "B", "C")
)
})
}
shinyApp(ui = ui, server = server)
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