How to display table data before and after filtering triggered from a click event in Shiny-CodePudding

I am trying to create an app that loads a csv into a table and then allows filtering by specific conditions that are triggered by click events on checkboxes and a htmlwidget. I can filter by the click event but the initial dataframe is not loaded. How can I resolve this issue? A very minimal kind of example is shown below:

library(shiny)
library(dplyr)
library(DT)

ui <- fluidPage(
  checkboxInput("filter1", "A filter"),
  DTOutput("table")
)

server <- function(input, output, session) {
  data <- reactive({ mtcars}) # this reads file input but I am using mtcars as substitute
  output$table <- DT::renderDT({DT::datatable(filter_1())})

  filter_1 <- reactive({
    req(input$filter1)
    # I want to load the CSV data in the table and then upon clicking on a widget or
    # checkbox only then should a given filter be applied
    if (is.null(input$filter1)) {data()} else {data() %>% filter(mpg > 25)}
    })
}

shinyApp(ui, server)

CodePudding user response：

req checks if a value is "truthy". filter1 is initialised with FALSE which is not "truthy", therefore the code for filter_1 is not executed. Only if you tick the checkbox, its value is TRUE and the data is shown. This means that in the if clause you need to check for TRUE/FALSE, not NULL.

In the example, you don't need req. To be on the safe side, you could explicitly check if filter1 is not NULL to not show weird error messages to the user during startup.

library(shiny)
library(dplyr)
library(DT)

ui <- fluidPage(
  checkboxInput("filter1", "A filter"),
  DTOutput("table")
)

server <- function(input, output, session) {
  data <- reactive({ mtcars}) # this reads file input but I am using mtcars as substitute
  output$table <- DT::renderDT({DT::datatable(filter_1())})
  
  filter_1 <- reactive({
    req(!is.null(input$filter1))
    # I want to load the CSV data in the table and then upon clicking on a widget or
    # checkbox only then should a given filter be applied
    if (input$filter1) {data() %>% filter(mpg > 25)} else {data()}
  })
}

shinyApp(ui, server)