Error expected an object with class 'shiny.tag'

[KafeelBasha]

Below is my code for the server part which returns error as shown in the screenshot.

library(shinydashboard)
library(dplyr)
library(shiny)
library(ggplot2)
server <- shinyServer(function(input,output,session){

  # read file
  values <- reactive({read.csv(input$file$datapath,na.strings=c(" ","","  ","   ")) })

  # observeEvent for input$file
  observeEvent(input$file, {

    # render tables at file upload
    output$data.frame <- renderTable(values())

    # update selectInput#Question
    updateSelectInput(
      session, 
      inputId = "Question",
      choices=names(values()),    
      selected=names(values()[,1])
    )

  })

  # observeEvent for input$Go
  observeEvent(input$Go, {
    # temp <- values([-input$Delete, ]    # commented for now
    # values <- temp                      # commented for now

    # commented for now
    library(tm)
    demo=Corpus(VectorSource(values()[,input$Question]))
    demo=tm_map(demo,content_transformer(tolower))
    demo=tm_map(demo,removePunctuation)
    df<- data.frame(text=unlist(sapply(demo,`[`)),stringsAsFactors=F)
    df$text=ifelse(df$text=="poor"|df$text=="fair","BAD",ifelse(df$text=="excellent"|df$text=="good","GOOD",NA))

    output$pos <- renderValueBox({

      # evaluate data: count, summarize, etc.
      positive<- df%>%
        filter(text=="GOOD") %>%count()    

      # make value box
      valueBox(positive,"Positive Response")
    })

    output$neg <- renderValueBox({

      # evaluate data: count, summarize, etc.
      negative<- df%>%
        filter(text=="BAD") %>%count()     

      # make value box
      valueBox(negative,"Negative Response")
    })

    output$nrow <- renderValueBox({

      #Number of records
      records<- nrow(df)
      # make value box
      valueBox(records,"Total number of responses")
    })

    output$bar <- renderPlot({

      #Bar chart
     ggplot(data=df,aes(text,fill=text))+geom_bar(aes(y = (..count..)/sum(..count..)))+geom_text(aes(y = ((..count..)/sum(..count..)), label = scales::percent((..count..)/sum(..count..))), stat = "count", vjust = -0.25)+xlab("Selected Feedback")+ylab("Response Proportion")
    })

    output$JigID<-renderTable({
      #Students who have given bad feedback
      values()[which(df[,"text"]=="BAD"),"sis_id"]
    })

  })

  observeEvent(input$file,{

    updateSelectInput(
      session, 
      inputId = "feeds",
      choices=names(values()),    
      selected=names(values()[,1])
    )})
  observeEvent(input$Go, {
  #Text analytics
  library(tm)
  feeds.corpus<-Corpus(VectorSource(values()[,input$feeds]))

  #Data Transformations -Cleaning
  feeds.corpus<-tm_map(feeds.corpus,tolower) #Converting to lower case
  feeds.corpus<-tm_map(feeds.corpus,stripWhitespace) #Removing extra white space
  feeds.corpus<-tm_map(feeds.corpus,removePunctuation) #Removing punctuations
  feeds.corpus<-tm_map(feeds.corpus,removeNumbers) #Removing numbers
  my_stopwords<-c(stopwords('english')) #Can add more words apart from standard list
  feeds.corpus<-tm_map(feeds.corpus,removeWords,my_stopwords)

  pos=c("good","very","best","satisfied","happy","excellent","nice","awesome","really","appreciate","easy","easier","precise","understand")
  neg=c("missed","lost","late","don't","not","tougher","difficult","bad","doesn't","difficulty","concern","uptick")

  #Famous Jeffreybreen Algorithm to "Tag" sentiments to sentences

  score.sentiment = function(sentences, pos.words, neg.words, .progress='none')
  {
    require(plyr)
    require(stringr)

    #we got a vector of sentences. plyr will handle a list
    #or a vector as an "l" for us
    #we want a simple array of scores back, so we use
    #"l" + "a" + "ply" = "laply":
    scores = laply(sentences, function(sentence, pos.words, neg.words) {

      #clean up sentences with R's regex-driven global substitute, gsub():
      sentence = gsub('[[:punct:]]', '', sentence) #removes punctuations
      sentence = gsub('[[:cntrl:]]', '', sentence) #removes control characters
      sentence = gsub('\\d+', '', sentence) #removes digits

      #and convert to lower case:
      sentence = tolower(sentence)

      #split sentences into words. str_split is in the stringr package
      word.list = str_split(sentence, '\\s+')

      #sometimes a list() is one level of hierarchy too much
      words = unlist(word.list)

      #compare our words to the dictionaries of positive & negative terms
      pos.matches = match(words, pos.words)
      neg.matches = match(words, neg.words)

      #match() returns the position of the matched term or NA
      #we just want a TRUE/FALSE:
      pos.matches = !is.na(pos.matches)
      neg.matches = !is.na(neg.matches)

      #and conveniently enough, TRUE/FALSE will be treated as 1/0 by sum():
      score = sum(pos.matches) - sum(neg.matches)

      return(score)
    }, pos.words, neg.words, .progress=.progress )

    scores.df = data.frame(score=scores, text=sentences)
    return(scores.df)
  }
  feeds.score<-score.sentiment(values()[,input$feeds], pos, neg, .progress="text")

  feeds.score$text<-as.character(feeds.score$text)
  feeds.score$sentiment<-ifelse(feeds.score$score>0,"positive",
                                ifelse(feeds.score$score<0,"negative","neutral"))
  #Classified feeds
  output$class_pos=renderValueBox({
    feeds.score%>%filter(sentiment=="positive")%>%count()
  })
  output$class_neg=renderValueBox({
    feeds.score%>%filter(sentiment=="negative")%>%count()
  })
  output$class_neu=renderValueBox({
    feeds.score%>%filter(sentiment=="neutral")%>%count()
  })
  })
  })

Please help.

[JesseVent]

It is more than likely your UI file, not your server file.

Check the inputs your providing into the UI functions and make sure they're correctly declared. See example below where by not including title= to the dashboardHeader function returns the same error you're experiencing.

library(shiny)
library(shinydashboard)

ui <- dashboardPage(
  dashboardHeader("Invalid Title"),
  # dashboardHeader(title="Valid Title"),
  dashboardSidebar(),
  dashboardBody()
)

server <- function(input, output) { }
shinyApp(ui, server)

> runApp('apppp.R')
[1] "Invalid Title"
Error in FUN(X[[i]], ...) : Expected an object with class 'shiny.tag'.

[sanjmeh]

was there a solution to this error?

[homer3018]

This code has certainly some issues:

output$class_neu=renderValueBox({
    feeds.score%>%filter(sentiment=="neutral")%>%count()
  })

However I'm also getting this error basically when I don't have data :

    output$foo<- renderValueBox({
        if(react() %>% nrow() < 1){
            return()
        }

        valueBox(react()$Perf[1] %>% percent(accuracy = 0.1),
                 color = "yellow")
    })

In this case NULL is returned and the error appears. Not sure how to best handle that.

[nlarusstone]

I see this also when I have a trailing comma sometimes -- removing the comma usually fixes it

[YongbingDing]

您好，丁永兵已经收到您的邮件，谢谢。