Shiny server functions with 2 outputs - r

Question

I'm trying to return two tables based on one input. Basically, I'm reading in a CSV and I want to display the values in the CSV in a table, then in a second table display a count of the number of rows in the CSV.
Right now I have
ui.R
ui <- fluidPage(
sidebarLayout(
sidebarPanel(
fileInput("file1", "Choose CSV File",
accept = c(
"text/csv",
"text/comma-separated-values,text/plain",
".csv")
),
tags$hr(),
checkboxInput("header", "Header", TRUE)
),
mainPanel(
tableOutput("rawData"),
tableOutput("rawDataSize")
)
)
)
and server.R
server <- function(input, output) {
output$rawData <- renderTable({
inFile <- reactive({input$file1})
data <- reactive({
if (is.null(inFile))
return(NULL)
read.csv(inFile$datapath, header = input$header)
})
})
output$rawDataSize <- renderTable({
dim(data)[1]
})
}
Unfortunately, this returns Warning: Error in as.data.frame.default: cannot coerce class "c("reactiveExpr", "reactive")" to a data.frame

Answer 1

Move inFile <- reactive({input$file1}) outside of renderTable. Then, to use this reactive object, you need to treat it like a function. inFile()$datapath. Same for your data reactive object.
So, your server() ends up looking something like:
server <- function(input, output) {
inFile <- reactive({input$file1})
data <- reactive({
if (is.null(inFile())) return(NULL)
read.csv(inFile()$datapath, header = input$header)
})
output$rawData <- renderTable({
data()
})
output$rawDataSize <- renderTable({
dim(data())[1]
})
}

Answer 2

1- A reactive is a function, so always add () when calling it.
2- Avoid nesting reactives:
server <- function(input, output) {
inFile <- reactive(input$file1)
data <- reactive({
if (is.null(inFile()))
return(NULL)
read.csv(inFile()$datapath, header = input$header)
})
output$rawData <- renderTable(data())
output$rawDataSize <- renderTable(dim(data())[1])
}