如何访问反应对象？闪亮的登录示例

分类：编程问答

如何解决如何访问反应对象？闪亮的登录示例

我在此link上找到了登录示例，但是我有一个问题：如何访问已登录的用户？我意识到此信息存储在名为auth的对象中，但是如何在不给出错误的情况下访问它？

# NOT RUN {
if (interactive()) {
  
  library(shiny)
  library(shinymanager)
  
  # data.frame with credentials info
  credentials <- data.frame(
    user = c("1","fanny","victor"),password = c("1","azerty","12345"),comment = c("1","alsace","auvergne"),stringsAsFactors = FALSE
  )
  
  # app
  ui <- fluidPage(
    
    # authentication module
    auth_ui(
      id = "auth",# add image on top ?
      tags_top = 
        tags$div(
          tags$h4("Demo",style = "align:center"),tags$img(
            src = "https://www.r-project.org/logo/Rlogo.png",width = 100
          )
        ),# add information on bottom ?
      tags_bottom = tags$div(
        tags$p(
          "For any question,please  contact ",tags$a(
            href = "mailto:someone@example.com?Subject=Shiny%20aManager",target="_top","administrator"
          )
        )
      ),# change auth ui background ?
      background  = "linear-gradient(rgba(0,255,0.5),rgba(255,0.5)),url('https://www.r-project.org/logo/Rlogo.png');"
    ),# result of authentication
    verbatimTextOutput(outputId = "res_auth"),# classic app
    headerPanel('Iris k-means clustering'),sidebarPanel(
      selectInput('xcol','X Variable',names(iris)),selectInput('ycol','Y Variable',names(iris),selected=names(iris)[[2]]),numericInput('clusters','Cluster count',3,min = 1,max = 9)
    ),mainPanel(
      plotOutput('plot1')
    )
  )
  
  server <- function(input,output,session) {
    
    # authentication module
    auth <- callModule(
      module = auth_server,id = "auth",check_credentials = check_credentials(credentials)
    )
    
    output$res_auth <- renderPrint({
      reactiveValuesToList(auth) ## <---- this line print which user is logged in

    })
    
    # classic app
    selectedData <- reactive({
      
      req(auth$result)  # <---- dependency on authentication result
      
      iris[,c(input$xcol,input$ycol)]
    })
    
    clusters <- reactive({
      kmeans(selectedData(),input$clusters)
    })
    
    output$plot1 <- renderPlot({
      palette(c("#E41A1C","#377EB8","#4DAF4A","#984EA3","#FF7F00","#FFFF33","#A65628","#F781BF","#999999"))
      
      par(mar = c(5.1,4.1,1))
      plot(selectedData(),col = clusters()$cluster,pch = 20,cex = 3)
      points(clusters()$centers,pch = 4,cex = 4,lwd = 4)
    })
  }
  
  shinyApp(ui,server)
  
}

如何访问auth $ user？下标越界错误正在发生，我想访问在应用程序内标记为“

我的个人情况：我正在尝试向MySQL数据库发送查询，如下所示：

  1. 尝试1（使用user_data（））
user_data <- reactive({
    req(auth$result)
    auth$user
  })

connection<-reactivePoll( intervalMillis = 300,session,checkFunc = function(){
    storiesDb <- dbConnect(RMariaDB::MariaDB(),user='USER',password=localuserpassword,dbname='USER',host='localhost')
    querysel1=reactive({paste("SELECT COL1
                 FROM   TABLENAME
                 where id ='",user_data(),"' ",sep= ''
    )})
    rs = dbSendQuery(storiesDb,querysel1)
    
    dbFetch(rs) },valueFunc = function(){
      
      querysel1=reactive({paste("SELECT COL1
                 FROM   TABLENAME
                 where id ='",sep= ''
                      
      )}) 
      rs = dbSendQuery(storiesDb,querysel1)
      dbFetch(rs)
    }
  )

我尝试使用user_data（），并给出错误：“无法为签名”“ MariaDBConnection”，“ reactiveExpr””'”找到函数'dbSendQuery'的继承方法

  1. 尝试2（不使用user_data（））
connection<-reactivePoll( intervalMillis = 300,auth$user,querysel1)

    dbFetch(rs) },valueFunc = function(){

      querysel1=reactive({paste("SELECT COL1
                 FROM   TABLENAME
                 where id ='",sep= ''

      )}) 
      rs = dbSendQuery(storiesDb,querysel1)
      dbFetch(rs)
    }
  )

我尝试使用auth $ user，并给出错误：“ as.vector（x，“ character”）错误：无法将类型'closure'强制转换为'character'类型的vector“

  1. 尝试3（在querysel1中不响应）
connection<-reactivePoll( intervalMillis = 300,host='localhost')
    querysel1=paste("SELECT COL1
                 FROM   TABLENAME
                 where id ='",sep= ''
    )
    rs = dbSendQuery(storiesDb,valueFunc = function(){

      querysel1=paste("SELECT COL1
                 FROM   TABLENAME
                 where id ='",sep= ''

      ) 
      rs = dbSendQuery(storiesDb,querysel1)
      dbFetch(rs)
    }
  )

我在querysel1中尝试了无反应式，并给出了空错误：“ Error：”

在我看来，所有这些错误都是由于服务器内部的反应对象而发生的。

解决方法

编辑

感谢提供reactivePoll的更多信息，我想我发现了问题：

这里的问题在于执行reactivePoll。启动应用程序时，reactivePoll已经开始执行，但是尚未登录任何用户。这意味着auth$user尚不存在（它是NULL），并且checkFun和valueFun中的代码无法处理。我提供了一个小示例（使用user = 1和password = 1）来说明它在原理上是可行的。只要auth$user为NULL，我就确保不执行代码：

library(shiny)
library(shinymanager)

# data.frame with credentials info
credentials <- data.frame(
  user = c("1","fanny","victor"),password = c("1","azerty","12345"),comment = c("1","alsace","auvergne"),stringsAsFactors = FALSE
)

# app
ui <- fluidPage(
  
  # authentication module
  auth_ui(
    id = "auth",# add image on top ?
    tags_top = 
      tags$div(
        tags$h4("Demo",style = "align:center"),tags$img(
          src = "https://www.r-project.org/logo/Rlogo.png",width = 100
        )
      ),# add information on bottom ?
    tags_bottom = tags$div(
      tags$p(
        "For any question,please  contact ",tags$a(
          href = "mailto:someone@example.com?Subject=Shiny%20aManager",target="_top","administrator"
        )
      )
    ),# change auth ui background ?
    background  = "linear-gradient(rgba(0,255,0.5),rgba(255,0.5)),url('https://www.r-project.org/logo/Rlogo.png');"
  ),# result of authentication
  verbatimTextOutput(outputId = "res_auth"),# classic app
  headerPanel('Iris k-means clustering'),sidebarPanel(
    selectInput('xcol','X Variable',names(iris)),selectInput('ycol','Y Variable',names(iris),selected=names(iris)[[2]]),numericInput('clusters','Cluster count',3,min = 1,max = 9)
  ),mainPanel(
    plotOutput('plot1'),textOutput("user_name")
  )
)

server <- function(input,output,session) {
  
  # authentication module
  auth <- callModule(
    module = auth_server,id = "auth",check_credentials = check_credentials(credentials)
  )
  
  output$res_auth <- renderPrint({
    reactiveValuesToList(auth) ## <---- this line print which user is logged in
    
  })
  
  # the following line is just an example how to use auth$user in a different
  # reactive
  user_data <- reactive({
    auth$user
  })
  
  # call the new reactive in a render function
  output$user_name <- renderText({
    paste0("The user currently logged in is: ",user_data())
  })
  
  # classic app
  selectedData <- reactivePoll(intervalMillis = 1000,session,checkFunc = function() {
                             if (!is.null(auth$user) && auth$user == "1") {
                               rnorm(1)
                             } else {
                               1
                             }
                           },valueFunc = function() {
                             n_row <- sample(1:150,120)
                             iris[n_row,c(input$xcol,input$ycol)]
                           })
  
  clusters <- reactive({
    kmeans(selectedData(),input$clusters)
  })
  
  output$plot1 <- renderPlot({
    palette(c("#E41A1C","#377EB8","#4DAF4A","#984EA3","#FF7F00","#FFFF33","#A65628","#F781BF","#999999"))
    
    par(mar = c(5.1,4.1,1))
    plot(selectedData(),col = clusters()$cluster,pch = 20,cex = 3)
    points(clusters()$centers,pch = 4,cex = 4,lwd = 4)
  })
}

shinyApp(ui,server)

我不确定为什么，但是仅添加req(auth$user)在这里行不通。

您可以执行以下操作：

connection<-reactivePoll( intervalMillis = 300,checkFunc = function(){
                            if (!is.null(auth$user)) {
                              storiesDb <- dbConnect(RMariaDB::MariaDB(),user='USER',password=localuserpassword,dbname='USER',host='localhost')
                              querysel1=paste("SELECT COL1
                 FROM   TABLENAME
                 where id ='",auth$user,"' ",sep= ''
                              )
                              rs = dbSendQuery(storiesDb,querysel1)
                              
                              dbFetch(rs)
                            } else {
                              NULL
                            }
                          },valueFunc = function(){
                            if (!is.null(auth$user)) {
                              querysel1=paste("SELECT COL1
                 FROM   TABLENAME
                 where id ='",sep= ''
                                              
                              ) 
                              rs = dbSendQuery(storiesDb,querysel1)
                              dbFetch(rs)
                            } else {
                              NULL
                            }
                          }
)

在这里，只要NULL不存在，我就返回auth$user，您可以根据需要进行调整。

我的旧答案：

我不确定您的问题/错误到底发生在哪里。对我来说，您的示例有效。我添加了另一个示例，说明如何访问auth$user。由于它是响应式的，因此只能在响应式上下文中访问它。

library(shiny)
library(shinymanager)

# data.frame with credentials info
credentials <- data.frame(
  user = c("1",user_data())
  })
  
  # classic app
  selectedData <- reactive({
    
    req(auth$result)  # <---- dependency on authentication result
    
    iris[,input$ycol)]
  })
  
  clusters <- reactive({
    kmeans(selectedData(),server)
,

要详细说明我的评论，也许最好显示代码：

请在注释中查看哪些语句有效，哪些无效。我只是将用户victor与通行证12345一起使用，而没有检查它是否与其他凭据一起使用。

library(shiny)
library(shinymanager)

# data.frame with credentials info
credentials <- data.frame(
  user = c("1",mainPanel(
    plotOutput('plot1')
  )
)

server <- function(input,check_credentials = check_credentials(credentials)
  )
  
  output$res_auth <- renderPrint({
    # reactiveValuesToList(auth$user) ## <---- not working
    auth[["user"]] ## <----  working
    # auth$user ## <----  this works too 
    # reactiveValuesToList(auth)[["user"]] # <--- this works too 
    
  })
  
  # classic app
  selectedData <- reactive({
    
    req(auth$result)  # <---- dependency on authentication result
    
    iris[,server)

}

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