Shiny中用于SQL查询的反应性文本

Question

我正在开发一个闪亮的应用程序，它从ui.R获取两个日期输入，并且（希望）将这些输入作为字符串传递给SQL查询。我一直在努力：

Error in cat(list(...), file, sep, fill, labels, append) : argument 1 (type 'closure') cannot be handled by 'cat'

这是ui.R：

library(shiny)

shinyUI(fluidPage(

  titlePanel(""),

  #create side tab list 
  sidebarLayout(
    sidebarPanel(

      selectInput("dataset", "Data:", 
                  choices = c("Alerts", "Jams")),

      checkboxGroupInput(

        inputId = "dataView", 
        label = "Add Data to Map", 

        choices = c(
                    "Polygon" = "poly",
                    "Points" = "data"
                  )),

      dateInput("dateStart", "Start Date: ", min = "2014-12-12", max = Sys.Date()),

      dateInput("dateEnd", "End Date: ", min = "2014-12-12", max = Sys.Date()),

      submitButton("Submit")
    ),


  mainPanel(
    tabsetPanel(type = 'tabs',
                tabPanel("Map", plotOutput("map")),
                tabPanel("Plots", plotOutput("plot")),
                tabPanel("Table", dataTableOutput(outputId = "table"))
                ),
    verbatimTextOutput("alert_query")
  )
  )
))

以下是删除了敏感信息的服务器.R的违规行为：

library(shiny)
library(dplyr)
library(RODBC)

shinyServer(function(input, output) {
  #query db

dateEnd_query <- renderText({
  reactive({
    input$dateEnd
  })
})



dateStart_query <- renderText({
  reactive({
    input$dateStart
  })
})

  wz <- odbcConnect("SQL", uid = "usr", pwd = "pwd" )

  output$alert_query <- renderText({
    reactive({
      paste("SELECT [vars] ", 
            "FROM  ",
            paste0("WHERE [startTime] >= ", "'", dateStart_query(),"'"),
            paste0("AND [startTime] <= ", "'", dateEnd_query() , "'"),
            "AND [city] = '' ")
    })

})
})