Call function, and return the value back to observeEvent in shiny app-CodePudding

I need to call a function inside observeEvent (which is based on select input), i need to call two functions, one is to get attribute name and other to get dataset name. i just wanna know how to call the function inside observeEvent.

library(shiny)
library(shinydashboard)

ui<-
  
  selectInput("select", "LPS tolerance induction:", c("", "LPS_Stim. at 0 h vs unstim" , "LOVE_Stim. at 20 h vs unstim",
                                                      "Restimulation (stim. at 0 h and 20 h vs unstim.)" ,
                                                      "Tolerance (stim. at 0 h and 20 h vs stim. at 20 h)"))

findattribute <- reactive({
  if(grepl("LPS",input$select)){
    x <- "val1"
    return(x)
  }
  else if(grepl("LOVE", input$select)){
    x <- "val2"
    return(x)
  }
  else if(grepl("Res", input$select)){
    x <- "val3"
    return(x)
  }
})

finddataset <- reactive({
  if(grepl("LPS",input$select)){
    x <- curated_lps # dataset name
    return(x)
  }
  
})

server<- function(input, output){
  
  observeEvent(input$select, {
    
    attribute <- findattribute()
    dataset <- finddataset()
  })
}

shinyApp(ui, server)

CodePudding user response：

Put the reactives inside the server, if not input not found error will occur.

Note than in this case observeEvent is redundant because findattribute() and finddataset() depend on input$select. If they were wrapped in isolate() then observeEvent() would make a difference.

server <- function(input, output, session) {
  
  findattribute <- reactive({
    if(grepl("LPS",input$select)){
      x <- "val1"
      return(x)
    }
    else if(grepl("LOVE", input$select)){
      x <- "val2"
      return(x)
    }
    else if(grepl("Res", input$select)){
      x <- "val3"
      return(x)
    }
  })
  
  finddataset <- reactive({
    if(grepl("LPS",input$select)){
      x <- curated_lps # dataset name
      return(x)
    }
    
  })
  
  observeEvent(input$select, {
    attribute <- findattribute()
    dataset   <- finddataset()
    print(attribute)
    print(dataset)
  })
}

If you need to keep the functions outside server you can define two functions that and then call them with input$select as an argument.

app:

library(shiny)
library(shinydashboard)

curated_lps <- iris

ui <-
  selectInput("select", "LPS tolerance induction:", c(
    "", "LPS_Stim. at 0 h vs unstim", "LOVE_Stim. at 20 h vs unstim",
    "Restimulation (stim. at 0 h and 20 h vs unstim.)",
    "Tolerance (stim. at 0 h and 20 h vs stim. at 20 h)"
  ))


findattribute <- function(input){
  if(grepl("LPS",input)){
    x <- "val1"
    return(x)
  }
  else if(grepl("LOVE", input)){
    x <- "val2"
    return(x)
  }
  else if(grepl("Res", input)){
    x <- "val3"
    return(x)
  }
}

finddataset <- function(input){
  if(grepl("LPS",input)){
    x <- curated_lps # dataset name
    return(x)
  }
  
}

# SERVER ------------------------------------------------------------------


server <- function(input, output, session) {
  
  observe({
    attribute <- findattribute(input$select)
    dataset   <- finddataset(input$select)
    print(attribute)
    print(dataset)
  })
}

shinyApp(ui, server)