Reactive function to read rtf in rshiny

Question

I am new to R and RShiny. Am building an application to compare two rtf files where a user can choose the two files dynamically. Is there a reactive function that I can use to read an rtf file before I pass it on to renderDiffr? Here is one version of the code I generated but the issue I am having is for these two rtf files I pick under folder1 and folder2 should be passed to renderDiffr below. I am sure there is a simple solution that I am yet to figure out. Would appreciate your help.

library(diffr)
library(shiny)

ui <- fluidPage(
  # Main title of the page
  titlePanel(HTML("<center>Comparison of two files</center>")),
  
  # Browse buttons to select files
  sidebarLayout(position="left",
                sidebarPanel(
                    #fileInput("selectfolder1","Select file from folder 1"),
                    #fileInput("selectfolder2","Select file from folder 2"),
                    # Submit button to perform the compare               
                    actionButton("goButton", "Compare", class = "btn-success")                   
                ),
  
  mainPanel(
    verbatimTextOutput("folder1"),
    verbatimTextOutput("folder2"),
    diffrOutput("value")
  )))


shinyServer(
  
  server <- function(input, output, session){
    
    re1<-reactive({
        file1<-file.choose()
    })
    
    output$folder1<-renderText({
        re1()
    })
    
    re2<-reactive({
        file2<-file.choose()
    })
    
    output$folder2<-renderText({
      re2()
    })    
    
    re3<-reactive({
      input$goButton
        x<-diffr(folder1,folder2, before="Folder 1",after="Folder 2")
    })
    
    output$value<-renderDiffr({
      re3()
    })  
}
)

shinyApp(ui, server)

Answer 1

According to this documentation you pass the result of diffr() to diffrOutput().

What I changed:

• When you use a reactive function make sure that you return the result at the end of it. I use return() for clarity (though it's not necessary).
• In diffr(folder1,folder2, ...) I used diffr(re1(), re2(), ...) for obvious reasons.
• I also skipped the re3 reactive In this sample and used diffr() directly in renderDiffr. But that is merely to reduce complexity.

library(diffr)
library(shiny)

ui <- fluidPage(
  # Main title of the page
  titlePanel(HTML("<center>Comparison of two files</center>")),
  
  # Browse buttons to select files
  sidebarLayout(position="left",
                sidebarPanel(
                  #fileInput("selectfolder1","Select file from folder 1"),
                  #fileInput("selectfolder2","Select file from folder 2"),
                  # Submit button to perform the compare               
                  actionButton("goButton", "Compare", class = "btn-success")                   
                ),
                
                mainPanel(
                  verbatimTextOutput("folder1"),
                  verbatimTextOutput("folder2"),
                  diffrOutput("FileDiff", width="600px", height="auto")
                )))


shinyServer(
  
  server <- function(input, output, session){
    
    re1<-reactive({
      file1<-file.choose()
      file1
    })
    
    output$folder1<-renderText({
      re1()
    })
    
    re2<-reactive({
      file2<-file.choose()
      file2
    })
    
    output$folder2<-renderText({
      re2()
    })    

    # re3<-reactive({
    #   input$goButton
    #   x<-diffr(folder1,folder2, before="Folder 1",after="Folder 2")
    #   return(x)
    # })
    
    output$FileDiff <- renderDiffr({
      input$goButton
      diffr(re1(), re2(), before="Folder 1", after="Folder 2")
    })  
  }
)

shinyApp(ui, server)