Web Application Development with R Using Shiny - Second Edition

Downloading and uploading data

Downloading data is done in a very similar fashion, which looks like the following downloadHandler() call:

output$downloadData <- downloadHandler(
  filename = function(){
    "myData.csv"
  }
  content = function(file){
    write.csv(passData(), file)
  }
)

Uploading data is achieved using the fileInput() function. In the following example, we will assume that the user wishes to upload a comma-separated spreadsheet (.csv) file. The button is added to ui.R in the following manner:

fileInput("uploadFile", "Upload your own CSV file")

This button allows a user to select their own .csv file, and it also makes a variety of objects based on the ID (in this case, input$uploadFile$...) available from server.R. The most useful is input$uploadFile$datapath ...