Shiny Input Controls

Complete reference for widgets, validation, and professional form design

1 Text & Numeric Inputs

# Text input
textInput("name", "Name:", 
          placeholder = "Enter your name")

# Text area
textAreaInput("comments", "Comments:", 
              rows = 4, resize = "vertical")

# Password
passwordInput("pwd", "Password:")

# Numeric input
numericInput("age", "Age:", 
             value = 25, min = 0, max = 120)

# Slider
sliderInput("range", "Range:",
            min = 0, max = 100, value = 50)

Access Pattern

input$name → Get text value
input$age → Get numeric value
input$range → Get slider value

2 Selection Controls

# Dropdown select
selectInput("country", "Country:",
            choices = c("USA", "UK", "Canada"))

# Multiple select
selectInput("vars", "Variables:",
            choices = names(mtcars),
            multiple = TRUE)

# Radio buttons
radioButtons("gender", "Gender:",
             choices = c("Male", "Female", "Other"))

# Checkboxes
checkboxGroupInput("features", "Features:",
                   choices = c("A", "B", "C"))

# Single checkbox
checkboxInput("agree", "I agree", FALSE)

Selection Tips: Use radio buttons for ≤5 options, dropdowns for many options, checkboxes for multiple selections

3 Date & File Inputs

# Date input
dateInput("start_date", "Start Date:",
          value = Sys.Date(),
          format = "yyyy-mm-dd")

# Date range
dateRangeInput("dates", "Date Range:",
                start = Sys.Date() - 30,
                end = Sys.Date())

# File upload
fileInput("file", "Choose File:",
          accept = c(".csv", ".xlsx"))

# Multiple files
fileInput("files", "Upload Files:",
          multiple = TRUE,
          accept = "image/*")

File Access

input$file$datapath → File location
input$file$name → Original filename
input$file$size → File size in bytes

4 Action Controls

# Action button
actionButton("run", "Run Analysis",
             class = "btn-primary",
             icon = icon("play"))

# Download button
downloadButton("download", "Download CSV",
               class = "btn-success")

# Action link
actionLink("help", "Show Help",
            icon = icon("question-circle"))

# Server: Handle button clicks
observeEvent(input$run, {
  # Your action code here
  showNotification("Analysis started!")
})

Button Styling: Use btn-primary, btn-success, btn-danger for different actions

5 Input Validation

# Basic validation
observe({
  validate(
    need(input$name != "", "Name is required"),
    need(nchar(input$name) >= 2, "Name too short")
  )
})

# Real-time feedback
output$email_feedback <- renderUI({
  if (grepl("@", input$email)) {
    div(class = "text-success", 
        icon("check"), "Valid email")
  } else {
    div(class = "text-danger", 
        icon("times"), "Invalid email")
  }
})

# File validation
observe({
  req(input$file)
  validate(
    need(input$file$size < 10 * 1024^2, "File too large")
  )
})

Validation Levels

validate() → Stop execution with message
req() → Require input before proceeding
renderUI() → Show real-time feedback

6 Dynamic & Custom Inputs

# Dynamic input generation
output$dynamic_inputs <- renderUI({
  lapply(1:input$num_inputs, function(i) {
    textInput(paste0("field_", i), 
              paste("Field", i, ":"))
  })
})

# Update input choices
observe({
  updateSelectInput(session, "variable",
                    choices = names(selected_data()))
})

# Conditional inputs
conditionalPanel(
  condition = "input.data_source == 'file'",
  fileInput("upload", "Upload File:")
)

# Custom styling
textInput("styled", "Custom Input:",
          class = "form-control-lg",
          style = "border-radius: 25px;")

Dynamic Tips: Use renderUI() for dynamic inputs, updateXXXInput() for changing existing inputs

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