Get value from reactive context in R shiny based on user input

r, shiny

Solution

as previously mentioned you would have to have your if statements in the reactive expression or `observe` Below is the working example of the sample App. Here I used a reactive expression to check which database you have selected. you can then use the mydb() and put it into your query, like so (I think this should work):

con <- dbConnect(MySQL(),dbname=mydb(), user="root", host="127.0.0.1", password="root")
query <- function(...) dbGetQuery(con, ...) 

A sample example is below

library(shiny)
library(ggplot2)
library(RMySQL)

ui =fluidPage(
  titlePanel("Shiny App"),
    sidebarPanel(selectInput("site", 
                              label = "Choose a site for Analysis",
                              choices = c("abc", "def","ghi", "jkl"),selected = "abc")),
    mainPanel(textOutput("text"),textOutput("db_select"))
  )


server = (function(input, output) {

  mydb <- reactive({

    if(input$site == "abc")
      {
        test <- c("testdb_abc")
      }
    else if(input$site == "def")
      {
        test <- c("testdb_def")
      } 
  })

  output$text <- renderText({  
    paste("You have selected:",input$site)
  })  

  query_output <- reactive({
    con <- (dbConnect(MySQL(),dbname=mydb(), user="root", host="127.0.0.1", password="root"))
    query <- function(...) dbGetQuery(con, ...)   
  })

  output$db_select <- renderText({  
    paste("My Database is:",mydb())
  })  
})


runApp(list(ui = ui, server = server))

Problem

Original source