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
Related
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$search, options)])
})
}
shinyApp(ui = ui, server = server)
I want to display choices to the user with a already preselected. Later, I would like to update the CheckboxGroupInput only after user starts typing into a search box . However, the checkbox seems to be updated immediately and the preselected choice a is not displayed.
Why does the observeEvent does not wait for interaction with the inputText? Any ideas how I could fix this and wait until user starts typing (I don't want to use button)?
Prevent execution of observe on app load in Shiny provides the answer. The observeEvent will just not be executed on start.
EDIT: (to make answer explicit as #lbusett suggested)
Setting ignoreInit = TRUE in the call to observeEvent solves the problem.
In the following example, the text is not shown in the start. If I click on the "show"-Button the text appears. If I then click on the "hide"-Button nothing else happens anymore.
In fact the "textis$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'm creating an web-app with Shiny in R. I have a dataset which I plot on the map. Using a checkboxGroupInput widget users are able to select categories they want to see on the map (or not). However, the dataset changes over time and not all categories are always available. To make clear which are available in the current set and which are not, I want to format the available categories as bold.
So far I've not been able to get a checkboxGroupInput widget to show with bold labels by the checkboxes. Is there a way to do that? I want some labels to be bold and others not. Also, using updateCheckboxGroupInput I'm able to change the options (i.e. show only available categories), but that not what I want/need.
I have tried for example:
x <- list("<b>A</b>"=1, "<b>B</b>"=2, "C"=3)
checkboxGroupInput(inputId="test", label="this is a test", choices=x)
But such an approach only displays the formatting tags as text in the user interface. Solutions using the HTML() function of Shiny doesn't seem to work either, or... I'm doing it wrong.
Any ideas?
Here is a simple Shiny interface example using the approach described above (which does not work):
library("shiny")
x <- list("<b>A</b>"=1, "<b>B</b>"=2, "C"=3)
server = function(input, output) {}
ui = fluidPage(
checkboxGroupInput(inputId="test", label="this is a test", choices=x)
)
runApp(list(ui = ui, server = server))
The next example DOES work, but it is a solution when initializing the checkbox group. Enabling the observe function in the server part shows that the same solution does not work for updateCheckboxGroupInput. That makes sense, since that function does not return HTML code. I don't know how to access the output of that update function, or how to solve it otherwise.
library("shiny")
x <- list("<b>A</b>"=1, "<b>B</b>"=2, "C"=3)
y <- list("<b>D</b>"=1, "<b>E</b>"=2, "F"=3)
server = function(input, output, session) {
# observe({
# input$test
# gsub(">", ">", gsub("<", "<", updateCheckboxGroupInput(session, "test", choices=y)))
# })
}
ui = fluidPage(
gsub(">", ">", gsub("<", "<", checkboxGroupInput(inputId="test", label="this is a test", choices=x)))
)
runApp(list(ui = ui, server = server))
For now I found a solution. Not really elegant, and probably prone to errors, but it works. I found out that the < and > characters are escaped for HTML purposes by the htmltools function called escapeHtml. By temporarily replacing that function before the updateCheckboxGroupInput is called, by a dummy function, the text is not escaped. After the updateCheckboxGroupInput is called, htmlEscape of course needs to be restored.
An example that works. After launching the app, you need to check the first box to see it work:
library("shiny")
x <- list("<b>A</b>"=1, "<b>B</b>"=2, "C"=3)
y <- list("<b>D</b>"=1, "<b>E</b>"=2, "F"=3)
server = function(input, output, session) {
observe({
value <- input$test
if (length(value) > 0 && value == 1) {
## save htmlEscape function and replace htmlEscape
saved.htmlEscape <- htmltools::htmlEscape
assignInNamespace("htmlEscape", function(x, attribute) return(x), "htmltools")
updateCheckboxGroupInput(session, "test", label="OK", choices=y)
## restore htmlEscape function
assignInNamespace("htmlEscape", saved.htmlEscape, "htmltools")
}
})
}
ui = fluidPage(
checkboxGroupInput(inputId="test", label="this is a test", choices=x)
)
runApp(list(ui = ui, server = server))
I have begun to create a web app using shiny where a user enters a search term and tweets containing that term are returned.
When I load this app the searchTwitter function begins automatically and on the main panel there is the error: Error: You must enter a query.
The search term is entered in the textInput box and there is a submitButton. You can enter a term and it works fine but I don't want the error to be the first thing the user sees.
ui.R:
library(shiny)
shinyUI(pageWithSidebar(
headerPanel("Twitter Generator"),
sidebarPanel(
textInput("search", "Search Twitter For:", value = ""),
submitButton("Search")
),
mainPanel(
h3(textOutput("search")),
tableOutput("view"),
)
))
server.R:
library(shiny)
library(twitteR)
shinyServer(function(input, output) {
datasetInput <- reactive(function(){
rawTweets <- twListToDF(searchTwitter(paste(input$search)))
rawTweets$cleanText <- as.vector(sapply(rawTweets$text, CleanTweet))
rawTweets[, colnames(rawTweets) != "created"]
})
output$search <- reactiveText(function() {
input$search
})
output$view <- reactiveTable(function() {
head(datasetInput())
})
})
Thanks for your help
This is a logical request for and from your application design, and you should think through how to do it.
One easy way would be to add a tickbutton providing a true/false and to skip the actual twitter search if the value is FALSE. You may need to cache the previous value of rawTweets, or set it to NULL, or ...
mainPanel(
h3(textOutput("search")),
tableOutput("view")
)
try it without the second ","