问题
I'm working on a shiny app and I'm running into difficulty with observeEvent() function when creating a complex expression of multiple inputs that all derive from selectInput().
My issue is some of the expressions within the observeEvent() function are triggered at startup, causing the event to prematurely execute (i.e. my actionButton() is disabled at startup, as it should be, but becomes enabled when at least one of the inputs are selected when ideally I would want it to become enabled only when ALL inputs are selected). As seen below:
observeEvent({
#input$cohort_file
input$cohort_IDvar
input$cohort_index_date
input$cohort_EOF_date
input$cohort_EOF_type
input$cohort_Y_name
input$cohort_L0
}, {
enable("set_cohort_button")
})
For reference, I'm using the shinyjs package by @daattali found on github to enable/disable actionButton().
All but the last input (i.e. input$cohort_L0) appear to be initialized at startup so observeEvent() enables actionButton only when input$cohort_L0 is selected. If you run my app and select input in sequential order from top to bottom, it appears that observeEvent() is working as intended. I only discovered that it wasn't working as intended when I decided to choose inputs at random and discovered that selecting input$cohort_L0 was the only input I needed to select to enable actionButton().
The UI portion of the code looks like this:
# Variable selection
selectInput('cohort_IDvar', 'ID', choices = ''),
selectInput('cohort_index_date', 'Index date', choices = ''),
selectInput('cohort_EOF_date', 'End of follow-up date', choices = ''),
selectInput('cohort_EOF_type', 'End of follow-up reason', choices = ''),
selectInput('cohort_Y_name', 'Outcome', choices = ''),
selectInput('cohort_L0', 'Baseline covariate measurements', choices = '', multiple=TRUE, selectize=TRUE),
And I'm using observe() to collect the column names of an upload data-set to direct them to selectInput() as follows:
### Collecting column names of dataset and making them selectable input
observe({
value <- c("",names(cohort_data()))
updateSelectInput(session,"cohort_IDvar",choices = value)
updateSelectInput(session,"cohort_index_date",choices = value)
updateSelectInput(session,"cohort_EOF_date",choices = value)
updateSelectInput(session,"cohort_EOF_type",choices = value)
updateSelectInput(session,"cohort_L0",choices = value)
})
I've looked into using the argument ignoreInit = TRUE but it does nothing for my case of having multiple expressions within observeEvent(). I've also looked into forcing no default selection in selectInput() but had no luck with that.
So my two-part question is how can I execute observEvent() when only ALL inputs are selected/how do I stop from the inputs from being initialized at startup?
My entire code:
library(shiny)
library(shinyjs)
ui <- fluidPage(
useShinyjs(),
navbarPage("Test",
tabPanel("Cohort",
sidebarLayout(
sidebarPanel(
fileInput("cohort_file", "Choose CSV File",
multiple = FALSE,
accept = c("text/csv",
"text/comma-separated-values,text/plain",
".csv")),
# Horizontal line ----
tags$hr(),
# Variable selection
selectInput('cohort_IDvar', 'ID', choices = ''),
selectInput('cohort_index_date', 'Index date', choices = ''),
selectInput('cohort_EOF_date', 'End of follow-up date', choices = ''),
selectInput('cohort_EOF_type', 'End of follow-up reason', choices = ''),
selectInput('cohort_Y_name', 'Outcome', choices = ''),
selectInput('cohort_L0', 'Baseline covariate measurements', choices = '', multiple=TRUE, selectize=TRUE),
# Horizontal line ----
tags$hr(),
disabled(
actionButton("set_cohort_button","Set cohort")
)
#actionButton("refresh_cohort_button","Refresh")
),
mainPanel(
DT::dataTableOutput("cohort_table"),
tags$div(id = 'cohort_r_template')
)
)
)
)
)
server <- function(input, output, session) {
################################################
################# Cohort code
################################################
cohort_data <- reactive({
inFile_cohort <- input$cohort_file
if (is.null(inFile_cohort))
return(NULL)
df <- read.csv(inFile_cohort$datapath,
sep = ',')
return(df)
})
rv <- reactiveValues(cohort.data = NULL)
rv <- reactiveValues(cohort.id = NULL)
rv <- reactiveValues(cohort.index.date = NULL)
rv <- reactiveValues(cohort.eof.date = NULL)
rv <- reactiveValues(cohort.eof.type = NULL)
### Creating a reactiveValue of the loaded dataset
observeEvent(input$cohort_file, rv$cohort.data <- cohort_data())
### Displaying loaded dataset in UI
output$cohort_table <- DT::renderDataTable({
df <- cohort_data()
DT::datatable(df,options=list(scrollX=TRUE, scrollCollapse=TRUE))
})
### Collecting column names of dataset and making them selectable input
observe({
value <- c("",names(cohort_data()))
updateSelectInput(session,"cohort_IDvar",choices = value)
updateSelectInput(session,"cohort_index_date",choices = value)
updateSelectInput(session,"cohort_EOF_date",choices = value)
updateSelectInput(session,"cohort_EOF_type",choices = value)
updateSelectInput(session,"cohort_L0",choices = value)
})
### Creating selectable input for Outcome based on End of Follow-Up unique values
observeEvent(input$cohort_EOF_type,{
updateSelectInput(session,"cohort_Y_name",choices = unique(cohort_data()[,input$cohort_EOF_type]))
})
### Series of observeEvents for creating vector reactiveValues of selected column
observeEvent(input$cohort_IDvar, {
rv$cohort.id <- cohort_data()[,input$cohort_IDvar]
})
observeEvent(input$cohort_index_date, {
rv$cohort.index.date <- cohort_data()[,input$cohort_index_date]
})
observeEvent(input$cohort_EOF_date, {
rv$cohort.eof.date <- cohort_data()[,input$cohort_EOF_date]
})
observeEvent(input$cohort_EOF_type, {
rv$cohort.eof.type <- cohort_data()[,input$cohort_EOF_type]
})
### ATTENTION: Following eventReactive not needed for example so commenting out
### Setting id and eof.type as characters and index.date and eof.date as Dates
#cohort_data_final <- eventReactive(input$set_cohort_button,{
# rv$cohort.data[,input$cohort_IDvar] <- as.character(rv$cohort.id)
# rv$cohort.data[,input$cohort_index_date] <- as.Date(rv$cohort.index.date)
# rv$cohort.data[,input$cohort_EOF_date] <- as.Date(rv$cohort.eof.date)
# rv$cohort.data[,input$cohort_EOF_type] <- as.character(rv$cohort.eof.type)
# return(rv$cohort.data)
#})
### Applying desired R function
#set_cohort <- eventReactive(input$set_cohort_button,{
#function::setCohort(data.table::as.data.table(cohort_data_final()), input$cohort_IDvar, input$cohort_index_date, input$cohort_EOF_date, input$cohort_EOF_type, input$cohort_Y_name, input$cohort_L0)
#})
### R code template of function
cohort_code <- eventReactive(input$set_cohort_button,{
paste0("cohort <- setCohort(data = as.data.table(",input$cohort_file$name,"), IDvar = ",input$cohort_IDvar,", index_date = ",input$cohort_index_date,", EOF_date = ",input$cohort_EOF_date,", EOF_type = ",input$cohort_EOF_type,", Y_name = ",input$cohort_Y_name,", L0 = c(",paste0(input$cohort_L0,collapse=","),"))")
})
### R code template output fo UI
output$cohort_code <- renderText({
paste0("cohort <- setCohort(data = as.data.table(",input$cohort_file$name,"), IDvar = ",input$cohort_IDvar,", index_date = ",input$cohort_index_date,", EOF_date = ",input$cohort_EOF_date,", EOF_type = ",input$cohort_EOF_type,", Y_name = ",input$cohort_Y_name,", L0 = c(",paste0(input$cohort_L0,collapse=","),"))")
})
### Disables cohort button when "Set cohort" button is clicked
observeEvent(input$set_cohort_button, {
disable("set_cohort_button")
})
### Disables cohort button if different dataset is loaded
observeEvent(input$cohort_file, {
disable("set_cohort_button")
})
### This is where I run into trouble
observeEvent({
#input$cohort_file
input$cohort_IDvar
input$cohort_index_date
input$cohort_EOF_date
input$cohort_EOF_type
input$cohort_Y_name
input$cohort_L0
}, {
enable("set_cohort_button")
})
### Inserts heading and R template code in UI when "Set cohort" button is clicked
observeEvent(input$set_cohort_button, {
insertUI(
selector = '#cohort_r_template',
ui = tags$div(id = "cohort_insertUI",
h3("R Template Code"),
verbatimTextOutput("cohort_code"))
)
})
### Removes heading and R template code in UI when new file is uploaded or when input is changed
observeEvent({
input$cohort_file
input$cohort_IDvar
input$cohort_index_date
input$cohort_EOF_date
input$cohort_EOF_type
input$cohort_Y_name
input$cohort_L0
}, {
removeUI(
selector = '#cohort_insertUI'
)
})
}
# Run the application
shinyApp(ui = ui, server = server)
回答1:
The code chunk that you're passing to the observeEvent as the trigger event is
{
input$cohort_IDvar
input$cohort_index_date
input$cohort_EOF_date
input$cohort_EOF_type
input$cohort_Y_name
input$cohort_L0
}
This means that, just like any other reactive code block, when ANY of these values changes, that reactive block is considered invalidated and therefore the observer will trigger. So the behaviour you're seeing makes sense.
It sounds like what you want is to execute only when all values are set. That sounds like a great use of the req() function! Try something like this:
observe({
req(input$cohort_IDvar, input$cohort_index_date, input$cohort_EOF_date, ...)
enable("set_cohort_button")
})
Note that for shinyjs::enable() specifically, you can instead use the shinyjs::toggleState() function. I think in this case the req() function is the better option though.
来源：https://stackoverflow.com/questions/55544176/shiny-r-observeevent-with-multiple-conditions-from-selectinput