R shiny does not display datatable

Question

I'm making a shiny app that displays the datatable with the results of a database query. I use an in-house package for retrieving the data and I'm sure this works correctly.

When I want to display the datatable from one of the db's I have no problems, but when I want to display the other the table simply doesn't appear.

I use the reactive function to retrieve the data and renderDataTable() for displaying it. Here is the code:

shinyServer(function(input, output) { dataset <- reactive({ if(input$experiment!=""&!is.null(input$experiment)){ if(input$db=="db1"){ data <- querydb1(experimentID=input$experiment) } if(input$db=="db2"){ data <- querydb2(experimentID=input$experiment) } } }) # output table output$data <- renderDataTable({ dataset() }) })

If you remove the data<- from before the querydb.. statements does that help? — John Paul
– John Paul, Commented Apr 2, 2014 at 15:29

Jeff Allen · Accepted Answer · 2014-04-02 23:24:06Z

1

Your reactive needs to return something. Try this:

if(input$experiment!=""&!is.null(input$experiment)){ if(input$db=="db1"){ data <- querydb1(experimentID=input$experiment) } if(input$db=="db2"){ data <- querydb2(experimentID=input$experiment) } return(data) }

answered Apr 2, 2014 at 23:24

Jeff Allen

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2 Comments

tertra Over a year ago

thanks this does the trick, still don't understand why db2 worked and bd1 not

Jeff Allen Over a year ago

By default R returns the last evaluated statement in an expression. So you don't technically need to call return at the end, you could just reference the variable data. Since db2 was the last evaluated block, it got returned if the conditional passed. db1's data was never the last evaluated statement, so it would never get returned.

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