Question

注销按钮（操作按钮）在以下脚本中不起作用。我需要知道它为什么不起作用？以及如何修复它？

仅供参考：当我从代码中取出USER$Logged <- FALSE时，该按钮有效但我无法再登录，因为Logged仍为TRUE。

欣赏！

UI

ui2 <- function(){
        tagList(tabPanel(""),
        pageWithSidebar(
        headerPanel(
            ""
        ),
        sidebarPanel
        (
            actionButton("logout", "Logout")        
        ),
            mainPanel(tableOutput('aaa'))
        )
    )   
}


ui1 <- function(){
    tagList(h2("Hello", align = "center"),
    div(id = "login",
        wellPanel(textInput("userName", "Username"),
                  passwordInput("passwd", "Password"),
                  br(),actionButton("Login", "Log in"),
  )
}

服务器

server = (function(input, output,session) {

USER <- reactiveValues(Logged=FALSE)
observe({ 
    if (USER$Logged == FALSE) {
      if (!is.null(input$Login)) {
        if (input$Login > 0) {
            Username <- isolate(input$userName)
            Password <- isolate(input$passwd)
            query <- sprintf({"
              SELECT rowid 
              FROM users 
              WHERE username='%s' and password ='%s'"}, 
                           Username, Password, serialize=F) 
            db   <- RSQLite::dbConnect(RSQLite::SQLite(), dbname="db.sqlite")
            user <- RSQLite::dbGetQuery(db, query) 
            RSQLite::dbDisconnect(db)
            if ( length(user$rowid)==1 ) {
              USER$Logged <- TRUE
          }
        } 
      }
    }    
})
observe({
    if (USER$Logged == FALSE)
    {
      output$page <- renderUI({div(class="outer",do.call(bootstrapPage,c("",ui1())))})
    }
    if (USER$Logged == TRUE) 
    {
      output$page <- renderUI({div(class="outer",do.call(navbarPage,c(inverse=TRUE,title = paste("Welcome", isolate(input$userName)," !"),ui2())))})
      print(ui)
    }
})
observeEvent(input$logout, {
    output$page <- renderUI({div(class="outer",do.call(bootstrapPage,c("",ui1())))})
    USER$Logged <- FALSE   
})

})

生成小型数据库：

library(shiny)
library(RSQLite)
setwd("E:/shiny/Correct")
db <- dbConnect(SQLite(), dbname="db.sqlite")
dbSendQuery(conn = db,"CREATE TABLE users (username TEXT, password TEXT, email TEXT)")
dbSendQuery(db, "INSERT INTO users ( username, password, email) VALUES ( 'ester', 'silva', 'abc@gmail.com');")

Answer 1

它无法正常工作，因为您无法在ui个对象之间进行切换。您可以做的是在uiOutput内创建ui，并在运行时在不同的用户界面之间切换。

这是一个简单的例子。您可以添加自己的登录逻辑等等。

library(shiny)

ui <- fluidPage(
  uiOutput("ui")
)

server <- function(input, output, session) {
  USER <- reactiveValues(Logged = FALSE)
  observe({
    if (USER$Logged == FALSE) {
      output$ui <- renderUI({
        tagList(
          h2("Hello", align = "center"),
          div(
            id = "login",
            wellPanel(
              textInput("userName", "Username"),
              passwordInput("passwd", "Password"),
              br(), actionButton("Login", "Log in")
            )
          )
        )
      })
    } else if (USER$Logged == TRUE) {
      output$ui <- renderUI({
        tagList(
          tabPanel(""),
          pageWithSidebar(
            headerPanel(
              ""
            ),
            sidebarPanel(
              actionButton("logout", "Logout")
            ),
            mainPanel(tableOutput("aaa"))
          )
        )
      })
    }
  })

  observeEvent(input$Login, {
    USER$Logged <- TRUE
  })

  observeEvent(input$logout, {
    USER$Logged <- FALSE
  })
}

shinyApp(ui, server)

为什么注销按钮不起作用-shiny R

1 个答案: