Using SQL Database Using Brilliant Queries

I want to use Shiny so that the user can create a data frame by accessing a SQL database. I want it to work like this (but open to suggestions):

• User types in ID (its number)
• User clicks an action button
• Reactive request is generated
• The request is sent and the data is fetched and added to the data frame
• User types in the following ID ...

Here's my attempt:

interface

library(markdown)

shinyUI(fluidPage(
  titlePanel("Generic grapher"),
  sidebarLayout(
    sidebarPanel(

  numericInput("wafer", label = h3("Select wafer ID:"), value = NULL),

  actionButton("do", "An action button")
  ),

  mainPanel(
    verbatimTextOutput("value"), verbatimTextOutput("que"), dataTableOutput(outputId="pos")
  )
)))

      

        
        
        
      

    

Server

library(RMySQL)
library(DBI)
library(sqldf)

con = dbConnect(RMySQL::MySQL(), dbname="Test_DB", username="pete", password="xx", host="xx", port=3306)
query <-  function(...) dbGetQuery(con, ...) 

wq = data.frame()
df = data.frame()

shinyServer(function(input, output){

  d <- eventReactive(input$do, { input$wafer })

  output$value <- renderPrint({ d() }) 

  a <- reactive({ paste("Select id from wafer where wafer_id=",d(), sep="") })

  output$que <- renderPrint({ a() }) 

  wq <- reactive({ rbind(wq, query( a() )) })

  output$pos <- renderDataTable({ wq() })
  })  

      

        
        
        
      

    

When I run I can see that both Id and the request will print correctly. However, I am getting this error when launching applications:

error in evaluating the argument 'statement' in selecting a method for function 'dbGetQuery': Error:

      

        
        
        
      

    

Then when I enter the plate id I get:

Error in xi[[j]] : object of type 'closure' is not subsettable

      

        
        
        
      

    

I know from these posts:

R shiny ERROR: object of type "closure" is not a subset

Error in <my code>: object of type "closure" is not a subset

What I am trying to multiply the underlying R function without specifying the variable name ... but I feel stupid, I looked at it for a day and couldn't see it. Maybe all my code is a bad way to query SQL brilliantly? Any help is appreciated.

Oh yes, ok ... if I change this:

wq <- reactive({ rbind(wq, query( a() )) })

      

        
        
        
      

    

:

wq <- reactive({  query( a() ) })

      

        
        
        
      

    

Then I get the output. So sorry, I guess my question changes to how to then populate the df with each action button click?