r - ggplot2 doesn't know how to deal with data of class reactive

Question

It seems that reactive encapsulated variables, so the variable inside tweets can not be accessed... so how to fix it ? or do not use reactive ?

the csv file tweets_davin and just use both for 2 upload

ui.r

library(shiny)
shinyUI(fluidPage(

  titlePanel("Text Mining"),
  br(),br(),

  sidebarLayout(
    sidebarPanel(
      h2("Davin", align = "center", style = "color:blue"),
      fileInput('file1', 'Choose CSV File', accept=c('.csv')),
      fileInput('file2', 'Choose CSV File', accept=c('.csv')),
      tags$hr()
    ),

    mainPanel(
      plotOutput("ditribusi")

    ))))

server.r

library(shiny)

shinyServer(function(input, output) {

  library(lubridate)
  library(ggplot2)
  library(dplyr)
  library(readr)

  tweets_1 <- reactive({
    req(input$file1)
    read.csv(input$file1$datapath)
  })

  tweets_2 <- reactive({
    req(input$file2)
    read.csv(input$file1$datapath)
  })  

    tweets <- reactive (
    as(bind_rows(tweets_1 %>% 
                          mutate(person = "satu"),
                        tweets_2 %>% 
                          mutate(person = "dua")) %>% 
    mutate(timestamp = ymd_hms(timestamp))))


    output$ditribusi <- renderPlot(
      ggplot(tweets, aes(x = timestamp, fill = person)) +
        geom_histogram(alpha = 0.5, position = "identity", bins = 20)
  )


})

error in RStudio

Warning: Error in : ggplot2 doesn't know how to deal with data of class reactive

Stack trace (innermost first):

105: fortify.default
104: fortify
103: structure
102: ggplot.data.frame
101: ggplot.default
100: ggplot
 99: renderPlot
 89: <reactive:plotObj>
 78: plotObj
 77: origRenderFunc
 76: output$ditribusi
  1: runApp

Answer 1

reactive returns a reactive expression, not a value. Basically it means that its current value can be accessed inside reactive context (inside functions like reactive, render* etc.) with calling it. I think this particular problem should be solved with the following code:

shinyServer(function(input, output) {

  library(lubridate)
  library(ggplot2)
  library(dplyr)
  library(readr)

  tweets_1 <- reactive({
    req(input$file1)
    read.csv(input$file1$datapath)
  })

  tweets_2 <- reactive({
    req(input$file2)
    read.csv(input$file1$datapath)
  })

  tweets <- reactive(
    bind_rows(tweets_1() %>% 
                mutate(person = "satu"),
              tweets_2() %>% 
                mutate(person = "dua")) %>% 
      mutate(timestamp = ymd_hms(timestamp))
    )

  output$ditribusi <- renderPlot(
    ggplot(tweets(), aes(x = timestamp, fill = person)) +
      geom_histogram(alpha = 0.5, position = "identity", bins = 20)
  )
})

For more information about using reactive expressions you can go to https://shiny.rstudio.com/tutorial/lesson6/