Clearing and re-reading variables in Shiny app - r

Question

I made an app that takes user input of a googlesheet and boxplots it https://sjgknight.shinyapps.io/boxplotr/ and https://github.com/uts-cic/BoxPlotR.shiny/.
It's mostly working. The inputs aren't reactive, the user has to click a button to read them. But (a) If I have a default 'value' in the input that causes problems, and (b) if a user changes their input and then it gives an error.
E.g. with this data https://docs.google.com/spreadsheets/d/1ycTplwz5q21s1Z3QzpeoP5rMKlkJnQ12GBJJyIU2_q0/ I should be able to create a 'Region' boxplot, and then change the input to 'Income', click the 'click to load data' button again, and I get an error unless I refresh and clear the URL.
Using the guidance at http://shiny.rstudio.com/articles/action-buttons.html I know I can create a 'clear' button that I guess removes all the values, but I'm not clear how I'd go about just re-reading the inputs. I have an isolate block and just tried setting the variables in that to NULL, which doesn't work. Welcome ideas on how to do this. Looking at other questions I'm mostly seeing issues around updating the UI based on user inputs passed to the server.
So, I figure I need to use observeEvent, but this doesn't seem to work:
observeEvent(
input$gloadsheet, {
isolate({
gs_data <- gs_url(input$gsheetURL)
data <- data.frame(gs_read(gs_data, ws = input$gsheetws))
data$nID <- row.names(data)
data <- reshape(data[c("nID",input$ggrouping,input$gdataID)], idvar = "nID", timevar = input$ggrouping, direction = "wide")
data <- data[,-c(1:2)]
data <- data.frame(data)
data
})
}
)
Alternatively, I thought I could use eventReactive per this question Shiny Reactivity Explaination (using ObserveEvent). It may be that the issue is the block this code is based in (which is a reactive to get a variable based on multiple options users can click through).
data <- eventReactive(input$gloadsheet, {
isolate({
gs_data <- gs_url(input$gsheetURL)
data <- data.frame(gs_read(gs_data, ws = input$gsheetws))
data$nID <- row.names(data)
data <- reshape(data[c("nID",input$ggrouping,input$gdataID)], idvar = "nID", timevar = input$ggrouping, direction = "wide")
data <- data[,-c(1:2)]
data <- data.frame(data)
})
data
})
data

Answer 1

You can try this on your server-side:
update <- reactiveValues(please = 0)
observeEvent(input$clearValues, {
updateTextInput(...) # Clear everything #
update$please <- update$please + 1
})
inYourRenderingFunction <- render..({
update$please
.
.
})
You create a reactive value that change after clear your inputs. Your render functions has to react to this reactive value (update$please)
I'm using this already. Hope it helps to you.