Trying to use Shiny SelectBox to Grab Data from SQL Server Table - r

Question

As the title says, I'm trying to get Shiny to display a SelectBox so I can dynamically select records from a SQL Server Table, and based on the selection of the CATEGORY, display everything in the table. The script below must be close. I am getting the SelectBox to work, but when I make a selection, nothing is displayed.
library(shiny)
library(RODBCext)
shinyApp(
ui =
shinyUI(
fluidPage(
uiOutput("select_category"),
tableOutput("display_data")
# plotOutput("plot_data")
)
),
server = shinyServer(function(input, output, session){
# A reactive object to get the query. This lets you use
# the data in multiple locations (plots, tables, etc) without
# having to perform the query in each output slot.
QueriedData <-
reactive({
req(input$showDrop)
ch <- odbcDriverConnect('driver={SQL Server};server=MyServer;database=Northwind;trusted_connection=true')
showList <- sqlExecute(ch,
"SELECT * FROM [NORTHWND].[dbo].[Customers] WHERE [CUSTOMERID] = ?",
data = list(AnalyteId = input$showDrop),
fetch = TRUE,
stringsAsFactors = FALSE)
odbcClose(ch)
showList
})
# The select input control. These can be managed dynamically
# from the server, and then the control send back to the UI
# using `renderUI`
output$select_category <-
renderUI({
ch <- odbcDriverConnect('driver={SQL Server};server=MyServer;database=Northwind;trusted_connection=true')
showList <- sqlExecute(ch,
"SELECT DISTINCT AnalyteId From [NORTHWND].[dbo].[Customers] ORDER BY [CUSTOMERID]",
fetch = TRUE,
stringsAsFactors = FALSE)
odbcClose(ch)
selectInput(inputId = "showDrop",
label = "Select Asset",
showList$AnalyteId)
})
# Display the data in a table
output$display_data <-
renderTable({
QueriedData()
})
# Display a plot
# output$plot_data <-
# renderPlot({
# plot(QueriedData()) # fill in the plot code you want to use.
# })
})
)
How can I get this working? Also, can you make the table dynamically selectable, or is that not an option?

Answer 1

It seems like you're missing some components. Some notes:
Your UI definition is invalid. Each argument to the UI should produce some kind of UI element. The lines where you define your connection and export the data from SQL Server will won't behave the way you are expecting them to here. You should either do these actions on the server, or you should define them globally.
You are retrieving data into your output$cumReturn slot, but you are using a renderPlot call to do it. This is somewhat disjoint. If you wish to render a plot, you should generate a plot. If you wish to show data, you should use renderTable (or something similar).
You also haven't displayed the cumReturn output slot anywhere in the UI, so the query is never actually being called.
Lastly, your query in output$cumReturn will fail when it goes to the server. I am guessing you mean to use input$showDrop in a WHERE statement, but your query has no such statement. This is not casting an error in the code above because you never try to render the cumReturn output, so the query is never being called.
Here's a variation on your code that should produce a table of data that fall within the category.
library(shiny)
library(RODBCext)
shinyApp(
ui =
shinyUI(
fluidPage(
uiOutput("select_category"),
tableOutput("display_data"),
plotOutput("plot_data")
)
),
server = shinyServer(function(input, output, session){
# A reactive object to get the query. This lets you use
# the data in multiple locations (plots, tables, etc) without
# having to perform the query in each output slot.
QueriedData <-
reactive({
req(input$showDrop)
ch <- odbcDriverConnect('...')
showList <- sqlExecute(ch,
"SELECT * FROM dbo.Analyte WHERE AnalyteId = ?",
data = list(AnalyteId = input$showDrop),
fetch = TRUE,
stringsAsFactors = FALSE)
odbcClose(ch)
showList
})
# The select input control. These can be managed dynamically
# from the server, and then the control send back to the UI
# using `renderUI`
output$select_category <-
renderUI({
ch <- odbcDriverConnect('...')
showList <- sqlExecute(ch,
"SELECT DISTINCT AnalyteId FROM dbo.Analyte ORDER BY AnalyteId",
fetch = TRUE,
stringsAsFactors = FALSE)
odbcClose(ch)
selectInput(inputId = "showDrop",
label = "Select Asset",
showList$AnalyteId)
})
# Display the data in a table
output$display_data <-
renderTable({
QueriedData()
})
# Display a plot
output$plot_data <-
renderPlot({
plot(QueriedData()) # fill in the plot code you want to use.
})
})
)

Answer 2

library(shiny)
library(RODBCext)
shinyApp(
ui =
shinyUI(
fluidPage(
uiOutput("select_category"),
tableOutput("display_data")
# plotOutput("plot_data")
)
),
# server needs the function; looks ok
server = shinyServer(function(input, output, session)
{
# A reactive object to get the query. This lets you use
# the data in multiple locations (plots, tables, etc) without
# having to perform the query in each output slot.
QueriedData <- reactive({
req(input$showDrop)
ch <- odbcDriverConnect("driver={SQL Server};server=SERVER;database=DB;trusted_connection=true")
showList <- sqlExecute(ch, "SELECT * FROM [DB].[dbo].[TABLE] WHERE Category = ?",
data = list(Category = input$showDrop),
fetch = TRUE,
stringsAsFactors = FALSE)
odbcClose(ch)
showList
})
# The select input control. These can be managed dynamically
# from the server, and then the control send back to the UI
# using `renderUI`
output$select_category <- renderUI({
ch <- odbcDriverConnect("driver={SQL Server};server=SERVER;database=DB;trusted_connection=true")
showList <- sqlExecute(ch, "Select Distinct Category From [DB].[dbo].[TABLE] Order by Category",
fetch = TRUE,
stringsAsFactors = FALSE)
odbcClose(ch)
selectInput(inputId = "showDrop",
label = "Select Asset",
showList$Category)
})
# Display the data in a table
output$display_data <- renderTable({
QueriedData()
})
# Display a plot
# output$plot_data <-
# renderPlot({
# plot(QueriedData()) # fill in the plot code you want to use.
# })
})
)