R shiny code to get output which takes input from ui - r

Question

I am trying to write a script in shiny, which has two inputs and stores the inputs in two different variables and runs a code using these input variables.But i am getting an error which says :Error in .getReactiveEnvironment()$currentContext() :
Operation not allowed without an active reactive context. (You tried to do something that can only be done from inside a reactive expression or observer.)
The following is my ui code:
ui <- fluidPage(
titlePanel("Network Model"),
sidebarLayout(
sidebarPanel(
selectInput(inputId = "origin",
label = "Origin:",
choices = milk_runs$Origin),
selectInput(inputId = "destination",
label = "Destination:",
choices = milk_runs$Dest),
actionButton("go", "")
),
mainPanel(
tableOutput(
"view"))
)
)
server code :
server<- function(input, output){
origin <- input$origin
destination <- input$destination
observeEvent(input$go,source("nr9.R"))
output$summary <- renderPrint({
#dataset <- datasetInput()
summary(Tnetwork)
})
Can you please tell me how to get correct results.

Answer 1

I think (it would help if you provided a fully reproducible example) that the error is occurring because you are trying to run input$origin without reactive(). The input$origin will not invalidate and update based on user input unless put inside reactive. Based on the example you provided:
library(shiny)
ui <- fluidPage(
titlePanel("Network Model"),
sidebarLayout(
sidebarPanel(
selectInput(inputId = "origin", label = "Origin:", choices = c("A","B","C","D","E","F")),
selectInput(inputId = "destination", label = "Destination:", choices = c("A","B","C","D","E","F")),
actionButton("go", "GO")
),
mainPanel( tableOutput( "view"))
)
)
server<- function(input, output){
origin <- reactive(input$origin)
destination<-reactive(input$destination)
observeEvent(input$go,{
cat(origin(),'nextword',destination(),sep="-")
})
output$view <- renderTable({data.frame(origin=origin(),destination=destination())})
}
shinyApp(ui, server)
should print 'origin-nextword-destination' to the console when 'go' is activated, and the table should update. I changed a few bits in your example because it was not reproducible but hopefully it helps.