Question

我在Rshiny中有一个反应式下拉框，其年份为2016年至2019年。用户选择年份后，必须将年份传递到以year为参数的sql查询中。

所以我尝试了下面给出的行（其中unique_vales2保留年份值）

 ---
 title: "Dashboard"
 output: 
 flexdashboard::flex_dashboard:
 orientation: rows
 vertical_layout: fill
 social: [ "twitter", "facebook", "menu"]
 runtime: shiny

 ```{r}
 mydb = dbConnect(MySQL(), user='xxx', password='xxx',dbname='xxx', 
 host='xxx')
 selectInput("year", "Choose year", choices = unique_values2) 
 num <- reactive(as.integer(input$year))
 rs=dbSendQuery(mydb,paste("select * from employees where Year=",num," group 
 by job;"))
 result=fetch(rs,n=-1)

 ```

但是当我尝试在上面给出的sql查询中使用num值时，

它显示：

错误：无法将'closure'类型强制转换为'character'类型的向量。

有什么办法解决吗？预先感谢。

Answer 1

假设以下数据在您的mysql表employees中，因为我没有实际数据。

dput(employees)
structure(list(id = 1:12, names = structure(1:12, .Label = c("aa", 
"bb", "cc", "dd", "ee", "ff", "gg", "hh", "ii", "jj", "kk", "ll"
), class = "factor"), year = c(2016, 2016, 2017, 2017, 2018, 
2018, 2016, 2018, 2017, 2019, 2019, 2019)), .Names = c("id", 
"names", "year"), row.names = c(NA, -12L), class = "data.frame")

下面的代码将帮助您满足您的要求

library(shiny)
library(DBI)
library(pool)
pool <- dbPool(drv = RMySQL::MySQL(),dbname = "db_name",host = "localhost",username = "user_name",password = "password", port = 3306, unix.sock = "/var/run/mysqld/mysqld.sock")

ui <- fluidPage(
  uiOutput("years"),
  tableOutput("mytable")
)

server <- function(input, output, session) {
  output$years <- renderUI({
    unique_values2 <- c(2016:2019)
    selectInput("year", "select year", choices = unique_values2)
  })

results <- reactive({
  df <- dbGetQuery(pool, paste0("SELECT * FROM employees WHERE year = ", input$year ," ;"))
  return(df)
})
output$mytable <- renderTable(results())
}

shinyApp(ui, server)

因此表格输出将根据我们从下拉菜单中选择的年份而变化。

如何在Rshiny反应式下拉框中获取选定选项的值？

1 个答案: