R: 'file' must be a character string or connection

I was using the Shiny app in R, and I was trying to read a file using fileInput control, but I faced the following error:

 
Listening on http://127.0.0.1:3558
Error in read.table(file = file, header = header, sep = sep, quote = quote,  :
  'file' must be a character string or connection


Problem code:

if(is.null(input$file1))
      return(NULL) 
file <- read.csv(file=input$file1,head=TRUE,sep=",", stringsAsFactors=FALSE)
csv <- str(file)


Solution:

inFile <- input$file1
if (is.null(inFile))
      return(NULL)    
csv <- read.csv(inFile$datapath, header=TRUE, sep=",")


The resolution was to use the datapath property of the input file and not the file itself.