Having following simple application:
library("shiny")
ui <- fluidPage(
uiOutput('model'),
textInput('search', 'Look for a model')
)
server <- function(input, output, session) {
options <- c('a', 'b', 'c', 'd')
output$model <- renderUI({
checkboxGroupInput("model",
"Select a model:",
options,
selected='a')
})
observeEvent(input$search,{
updateCheckboxGroupInput(session,"model",
"Select a model:",
options[grep(input$search, options)])
})
}
shinyApp(ui = ui, server = server)
I want to display choices to the user with a already preselected. Later, I would like to update the CheckboxGroupInput only after user starts typing into a search box . However, the checkbox seems to be updated immediately and the preselected choice a is not displayed.
Why does the observeEvent does not wait for interaction with the inputText? Any ideas how I could fix this and wait until user starts typing (I don't want to use button)?
Prevent execution of observe on app load in Shiny provides the answer. The observeEvent will just not be executed on start.
EDIT: (to make answer explicit as #lbusett suggested)
Setting ignoreInit = TRUE in the call to observeEvent solves the problem.
Related
I have a simple shiny app where the user should input comma-separated values into a text input, chose the output and click on a button to convert to an output.
I have followed the advice in Update content on server only after I click action button in Shiny to change the output only when clicking, and it works.
However, only when starting/ opening the app the first time, the field is empty, yet the output seems to try to evaluate the input field.
It is more of a cosmetic problem, because once the user filled something in, this does not recur, but I wonder how I could avoid this...
My app:
library(shiny)
ui <- fluidPage(
textInput("from", "csv", value = NULL),
actionButton("run", "Run"),
textOutput("to")
)
server <- function(input, output, session) {
list1 <- reactive({
input$run
x <- isolate(paste(read.table(text = input$from, sep = ",")))
x
})
output$to <- renderText({
list1()
})
}
shinyApp(ui = ui, server = server)
The not-desired output - I would like to get rid of the errors.
you can use req(input$from), see Check for required values
In the following example, the text is not shown in the start. If I click on the "show"-Button the text appears. If I then click on the "hide"-Button nothing else happens anymore.
In fact the "textis$visible" variable has always the correct value, but i think the if-statement in the observeEvent funktion is only calculated after the very first button click.
Is there a way to force observeEvent to re-evaluate the if statement? Or are there other ways to stop shiny from executing code in the server part and restart it again (in the real case there would be a whole bunch of function calls inside the if statement, not just hide and show some text)
library(shiny)
ui <- fluidPage(
actionButton(inputId="show","show"),
actionButton(inputId="hide","hide"),
textOutput(outputId = "some_text")
)
server <- function(input, output) {
textis<-reactiveValues(visible=FALSE)
observeEvent(input$show,
textis$visible<-TRUE)
observeEvent(input$hide,
textis$visible<-FALSE)
observeEvent(textis$visible , if(textis$visible){
output$some_text<-renderText({"this is some text"})
})}
shinyApp(ui = ui, server = server)
The observeEvent expressions are evaluated any time the value of their event expression changes. But, in the code you have above, when textis$visible changes, the observer only has instructions to perform if textis$visible is true. In the code snippet below, I've used else{...} to give that observer an action to perform when testis$visible is not true.
observeEvent(textis$visible , if(textis$visible){
output$some_text<-renderText({"this is some text"})
} else {output$some_text<-renderText({''}) }
)}
So, if you paste the else clause above into your app, the output some_text will disappear when the hide button is clicked.
It is not very good practice to put a render element in an observer (and it is unnecessary). Also since you have only one reactiveValue, you could use reactiveVal(), see the example below. You can call its value with text_visible(), and update it with text_visible(new_value).
Working example:
library(shiny)
ui <- fluidPage(
actionButton(inputId="show","show"),
actionButton(inputId="hide","hide"),
textOutput(outputId = "some_text")
)
server <- function(input, output) {
text_visible<-reactiveVal(TRUE)
observeEvent(input$show,
text_visible(TRUE))
observeEvent(input$hide,
text_visible(FALSE))
output$some_text<-renderText({
if(text_visible())
return("this is some text")
else
return("")
})
}
shinyApp(ui = ui, server = server)
try something like this:
library(shiny)
ui <- fluidPage(
actionButton(inputId="show","show"),
actionButton(inputId="hide","hide"),
textOutput(outputId = "some_text")
)
server <- function(input, output) {
textis <- reactiveVal(F)
observeEvent(input$show,{textis(T)})
observeEvent(input$hide,{textis(F)})
result <- eventReactive(textis(),{
if(!textis()){
return()
}
"this is some text"
})
output$some_text<-renderText({result()})
}
shinyApp(ui = ui, server = server)
I am having a lot of trouble getting a search filtering module working.
I am to run stats on a large database of cat owner information.
I want my search module to bring up a list of possible owners(that the user can select from) based on a selection from a list of cat breeds.
I thought wrapping the updateSelectInput with observe and using a reactive cat owner expression would facilitate this, in the module, but it is not working( and I can't guess why this is happening or how to debug this). It worked in these other posts([1]:R shiny passing reactive to selectInput choices , [2]:using values from a reactive input to directly input into a custom function)
Why won't my selectInput update with cat owners?
library(shiny)
df=data.frame(
cat=c("tabby","DSH","MSH","LSH","DSH","MSH","LSH","sphinx"),
owner=c("Foo","Bar","Bash","Foo","Foo","Foo","Bar","Bash"),stringsAsFactors = F)
refinedSearch<-function(input, output, session){
ownsCat<-reactive({df[df$cat%in%input$cat,"owner"]})
observe({updateSelectInput(session, "ownerSelected",
label ="Owned By",choices = ownsCat())})
return()
}
refinedSearchUI<-function(id){
ns <- NS(id)
fluidRow(
column(4,selectInput(ns("cat"),"Cat",selectize = T,
choices =c("tabby","DSH","MSH","LSH","sphinx") )),
column(4,selectInput(ns("ownerSelected"),"Owned By","",selectize = T))
)
}
ui <- fluidPage(
h1("Find cats owners"),
fluidRow(column(10,offset=1, refinedSearchUI("tmp"))),
fluidRow(column(10,offset=1, actionButton("addFilter","Add a Filter",
icon = icon("plus"))))
)
server <- function(input, output,session) {
refinedSearch(input,output,session)
observeEvent(input$add, {insertUI(selector = "#addFilter",where = "beforeBegin",
ui = refinedSearch(input,output,session))})
}
shinyApp(ui = ui, server = server)
Thank y'all for you time.
There seems to be quite a bit of confusion on how to call modules. You need to use the callModule() function in the server. Also, when inserting UI (using the insertUI()function), you need to call the refinedSearchUI() function, not the refinedSearch() function (which, again, should always be called through callModule(), so it should never actually get called directly like that).
I'd recommend a re-reading of the modules article.
You also have a typo. The event in your observeEvent() function should be input$addFilter, not input$add (which doesn't exist, so that observer is never fired..)
If you change your server function to this, your app will work as expected:
server <- function(input, output,session) {
callModule(refinedSearch, "tmp")
observeEvent(input$addFilter, {
id <- paste0("filter_", input$add)
insertUI(selector = "#addFilter",where = "beforeBegin",
ui = refinedSearchUI(id))
callModule(refinedSearch, id)
})
}
I am trying to modularize a complex Shiny app for which I have a conditionalPanel that should only appear given a certain input state.
Before I made everything modular, the input and conditionalPanel were both in ui.R, and I could reference the input using something like this:
conditionalPanel("input.select == 'Option one'", p('Option one is selected'))
Now that I have modularized things, accessing the input is more complicated. I thought the following was the way to do it, but it doesn't quite work. (Here I've combined things into a single standalone script):
library(shiny)
## Module code for 'selectorUI' and 'selector'
selectorUI <- function(id) {
ns <- NS(id)
selectizeInput(inputId = ns('select'),
label = 'Make a choice:',
choices = c('Option one', 'Option two'))
}
selector <- function(input, output, session) {
reactive(input$select)
}
## Main app
ui <- shinyUI(fluidPage(
selectorUI('id1'),
conditionalPanel(condition = "output.selected == 'Option one'", p('Option one is selected.'))
))
server <- shinyServer(function(input, output, session) {
output$selected <- callModule(selector, 'id1')
})
shinyApp(ui = ui, server = server)
I think this should work, but it doesn't - it only works if I make another reference to output$selected in the main ui section:
ui <- shinyUI(fluidPage(
selectorUI('id1'),
textOutput('selected'), ## Adding just this one line makes the next line work
conditionalPanel(condition = "output.selected == 'Option one'", p('Option one is selected.'))
))
Unfortunately of course this has the unwanted effect of rendering the result of textOutput('selected'). I can only guess that the reason this works is because it somehow triggers the reactive in a way that the JavaScript reference alone does not.
Any idea how I should be getting this conditionalPanel to work properly?
Thank you..
EDIT: Turns out not actually a bug: https://github.com/rstudio/shiny/issues/1318. See my own answer below.
But also note that I actually like the renderUI solution given in the accepted answer better than my original conditionalPanel approach.
After calling the module the ID of selectizeInput is id1-select. In javaScript there are two ways of accessing object properties:
objectName.property or objectName['property']
Since there is - in the ID we have to refer to it via string, so the second method is way to go.
The condition in conditionalPanel becomes:
input['id1-select'] == 'Option one'
Full example:
library(shiny)
## Module code for 'selectorUI' and 'selector'
selectorUI <- function(id) {
ns <- NS(id)
selectizeInput(inputId = ns('select'),
label = 'Make a choice:',
choices = c('Option one', 'Option two'))
}
## Main app
ui <- shinyUI(fluidPage(
selectorUI('id1'),
conditionalPanel(condition = "input['id1-select'] == 'Option one'",
p('Option one is selected.'))
))
server <- shinyServer(function(input, output, session) {
})
shinyApp(ui = ui, server = server)
EDIT:
This does work, but doesn't it violate the notion of modularity? You would have to know the code for the module internally calls that input 'select' in order to construct 'id1-select'.
Yes, you're right.
According to this article, the trick you used i.e. assigning a module call to the output$selected and then accessing its value on the client side via output.selected should work but it doesn't. I don't know why...it is maybe a bug. (I have the newest shiny version from github)
The only thing I can think of is to use renderUI instead of conditionalPanel as in the example below:
library(shiny)
## Module code for 'selectorUI' and 'selector'
selectorUI <- function(id) {
ns <- NS(id)
selectizeInput(inputId = ns('select'),
label = 'Make a choice:',
choices = c('Option one', 'Option two'))
}
selector <- function(input, output, session) {
reactive(input$select)
}
## Main app
ui <- shinyUI(fluidPage(
selectorUI('id1'),
uiOutput("dynamic1")
))
server <- shinyServer(function(input, output, session) {
output$dynamic1 <- renderUI({
condition1 <- callModule(selector, 'id1') # or just callModule(selector, 'id1')()
if (condition1() == 'Option one') return(p('Option one is selected.'))
})
})
shinyApp(ui = ui, server = server)
Turns out it actually isn't a bug, just a little tricky. According to Joe Cheng,
Right--we don't, by default, calculate/render output values if they aren't going to be visible. And if we don't calculate them, you can't use them in conditions.
You can change this behavior this by setting an output to calculate every time, you can use this in your server.R (replace outputId with the corresponding value):
outputOptions(output, "outputId", suspendWhenHidden = FALSE)
So to fix the problem with my original example, we only need to add that one line to the server function:
server <- shinyServer(function(input, output, session) {
output$selected <- callModule(selector, 'id1')
outputOptions(output, 'selected', suspendWhenHidden = FALSE) # Adding this line
})
I have a rather complex Shiny application and something weird happens:
When I print out some of my intermediate steps the App makes, everything gets printed out twice. That means, everything gets evaluated etc. twice.
I know without seeing the progamme its rather hard to tell what causes the problem, but maybe someone can pin point me (based on experierence/knowledge) what might be the problem.
Like I mentioned in the comment, isolate() should solve your problem.
Beyond the documentation of Rstudio http://shiny.rstudio.com/articles/reactivity-overview.html
I recommend the following blog article for interesting informations beyond the RStudio docu.
https://shinydata.wordpress.com/2015/02/02/a-few-things-i-learned-about-shiny-and-reactive-programming/
In a nutshell, the easiest way to deal with triggering is to wrap your code in isolate() and then just write down the variables/inputs, that should trigger changes before the isolate.
output$text <- renderText({
input$mytext # I trigger changes
isolate({ # No more dependencies from here on
# do stuff with input$mytext
# .....
finishedtext = input$mytext
return(finishedtext)
})
})
Reproducible example:
library(shiny)
ui <- fluidPage(
textInput(inputId = "mytext", label = "I trigger changes", value = "Init"),
textInput(inputId = "mytext2", label = "I DONT trigger changes"),
textOutput("text")
)
server <- function(input, output, session) {
output$text <- renderText({
input$mytext # I trigger changes
isolate({ # No more dependencies from here on
input$mytext2
# do stuff with input$mytext
# .....
finishedtext = input$mytext
return(finishedtext)
})
})
}
shinyApp(ui, server)
I encountered the same problem when using brush events in plotOutput. The solution turned out to be resetOnNew = T when calling plotOutput to prevent changes in my plot causing the brush event to be evaluated again.