Demo eventReactive() - subset data on click of button and display the resultant data

action1.R

# Demo example for eventReactive()
# Create dependency on a button to reflect user input changes to the rendered output 
# subset data on click of button and display the resultant data

# Load the required libraries
library(shiny) # for Shiny components
library(dplyr) # for piping and data manipulation

# For demo using the mtcars dataset
# convert the cylinder variable to factor type
my = mtcars %>% 
  mutate(cyl = as.factor(cyl))

## ui component starts here
ui <- fluidPage(
  h3("Demo on eventReactive() function"),
  h4("Use case - Subset dataset basis user selection and display subset data on click of action button"),
  hr(),
  # SliderInput
  sliderInput(inputId = "miles", 
              label ="Select miles per gallon range", 
              dragRange = TRUE, 
              min= min(my$mpg),
              max = max(my$mpg),
              value = c(15, 25)
  ),
  
  #RadioButton
  radioButtons(inputId = "cyl" , 
               label ="Select the cylinder #" , 
               choices =levels((my$cyl)) , 
               selected = 4, 
               inline = TRUE),
  
  
  # Action button
  actionButton(inputId ="show" ,label = "Show Data"),
  
  # Data Table
  tableOutput("table")
)

server <- function(input, output, session) {
  
  filter <- eventReactive(eventExpr = input$show, 
                valueExpr = {
                  dplyr::filter(my, 
                                cyl==input$cyl,
                                mpg>=input$miles[1] & mpg<=input$miles[2])
                  
                }, ignoreNULL = FALSE
                  )
  
  # Display the filtered table
  output$table <- renderTable({
    filter()
    
  })
  
  
 
}

shinyApp(ui, server)