我正在研究一个闪亮的应用程序，当我创建一个多个输入的复杂表达式时，我遇到了observeEvent()函数的困难，这些输入都来自selectInput()。
我的问题是observeEvent()函数中的一些表达式在启动时被触发，导致事件过早地执行（即我的actionButton()在启动时被禁用，因为它应该是，但是当理想情况下选择至少一个输入时启用我希望它只在选择了所有输入时才能启用）。如下所示：
observeEvent({
#input$cohort_file
input$cohort_IDvar
input$cohort_index_date
input$cohort_EOF_date
input$cohort_EOF_type
input$cohort_Y_name
input$cohort_L0
}, {
enable("set_cohort_button")
})
作为参考，我使用在github上找到的@daattali的shinyjs包来启用/禁用actionButton()。
除了最后一个输入（即input$cohort_L0）之外的所有输入似乎都是在启动时初始化的，所以observeEvent()仅在选择actionButton时启用input$cohort_L0。如果您运行我的应用程序并按顺序从上到下选择输入，则observeEvent()似乎正在按预期工作。当我决定随机选择输入并发现选择input$cohort_L0是我需要选择启用actionButton()的唯一输入时，我才发现它没有按预期工作。
代码的UI部分如下所示：
# 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),
我正在使用observe()收集上传数据集的列名，以便将它们定向到selectInput()，如下所示：
### 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)
})
我已经研究过使用ignoreInit = TRUE这个参数，但它对我在observeEvent()中有多个表达式的情况没有任何帮助。我也考虑过在selectInput()强制没有默认选择，但没有运气。
所以我的两部分问题是，当只选择所有输入时如何执行observEvent() /如何在启动时停止输入的初始化？
我的整个代码：
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$cohort_L0
}, {
removeUI(
selector = '#cohort_insertUI'
)
})
}
# Run the application
shinyApp(ui = ui, server = server)
您作为触发器事件传递给observeEvent的代码块是
{
input$cohort_IDvar
input$cohort_index_date
input$cohort_EOF_date
input$cohort_EOF_type
input$cohort_Y_name
input$cohort_L0
}
这意味着，就像任何其他反应性代码块一样，当这些值中的任何一个发生变化时，该反应块被认为是无效的，因此观察者将触发。所以你看到的行为是有道理的。
听起来你想要的只是在设置了所有值时执行。这听起来像是req()功能的很好用！尝试这样的事情：
observe({
req(input$cohort_IDvar, input$cohort_index_date, input$cohort_EOF_date, ...)
enable("set_cohort_button")
})
请注意，对于shinyjs::enable()，您可以改为使用shinyjs::toggleState()函数。我认为在这种情况下，req()功能是更好的选择。