shiny fileinput r dataframe - r

Question

Using R shiny, I am developing a simple app that allows user to input data from a file. With csv or txt files everything works fine, but I can not make R dataframes to load.
## SERVER.R
shinyServer(function(input, output) {
infile <- reactive({
infile <- input$datafile
if (is.null(infile)) {
# User has not uploaded a file yet
return(NULL)
}
infile<load(input$datafile$datapath)
})
myData <- reactive({
df<-infile()
if (is.null(df)) return(NULL)
})
output$value1 <- renderPrint({
names(iris)
})
output$value2 <- renderPrint({
names(myData())
})
load("iris.Rdata") ## data loaded for testing
})
## UI.R
shinyUI(fluidPage(
fileInput("datafile", label = h3("File input")),
fluidRow(column(4, verbatimTextOutput("value1"))),
fluidRow(column(4, verbatimTextOutput("value2")))
))
When I run this app I can see the names of the iris dataset loaded only for testing, but respect the names of the loaded file (which should be rendered as value2) only shows "NULL"
Any help?? thanks in advance!

Answer 1

I think this is what you want. You had a couple of typos, and you probably didn't quite understand what load actually does, it loads a set of objects into memory.
I did the following things:
added some initialization code to save a couple of .Rdata for testing, they both have exactly one object in them, a dataframe. The code needs this.
add a line to parse out the first object in that loaded datafile and return it
Here is the code:
server.r
## SERVER.R
#Initialization
library(datasets)
save(iris,file="iris.Rdata")
save(mtcars,file="m.Rdata")
shinyServer(function(input, output) {
infile <- reactive({
infile <- input$datafile
if (is.null(infile)) {
# User has not uploaded a file yet
return(NULL)
}
objectsLoaded <- load(input$datafile$name)
# the above returns a char vector with names of objects loaded
df <- eval(parse(text=objectsLoaded[1]))
# the above finds the first object and returns it
return(df)
})
myData <- reactive({
df<-infile()
if (is.null(df)) return(NULL)
return(df)
})
output$value1 <- renderPrint({
names(iris)
})
output$value2 <- renderPrint({
names(myData())
})
load("iris.Rdata") ## data loaded for testing
})
ui.r
## UI.R
shinyUI(fluidPage(
fileInput("datafile", label = h3("File input")),
fluidRow(column(4, verbatimTextOutput("value1"))),
fluidRow(column(4, verbatimTextOutput("value2")))
))
Here is the output: