[英]csv file upload at start of r shiny app (quasi placeholder file)
With this code I can upload a csv file in my shiny app.使用此代码,我可以在我的 shiny 应用程序中上传一个 csv 文件。
library(shiny)
ui <- fluidPage(
sidebarLayout(
sidebarPanel(
fileInput("file1", "Choose CSV File", accept = ".csv"),
checkboxInput("header", "Header", TRUE)
),
mainPanel(
tableOutput("contents")
)
)
)
server <- function(input, output) {
output$contents <- renderTable({
file <- input$file1
ext <- tools::file_ext(file$datapath)
req(file)
validate(need(ext == "csv", "Please upload a csv file"))
read.csv(file$datapath, header = input$header)
})
}
shinyApp(ui, server)
I would like to load a placeholder csv file say df.csv
automatically at the start of my shiny app.我想在我的 shiny 应用程序开始时自动加载一个占位符 csv 文件,比如df.csv
。
I this possible or do I have rethink my strategy?这是可能的还是我已经重新考虑了我的策略?
In the server
, we may use if/else
to create the placeholder .csv
while loading在server
中,我们可以在加载时使用if/else
创建占位符.csv
server <- function(input, output) {
output$contents <- renderTable({
if(is.null(input$file1)) {
dat <- read.csv(file.path(getwd(), "df.csv"))
} else {
file <- input$file1
ext <- tools::file_ext(file$datapath)
req(file)
validate(need(ext == "csv", "Please upload a csv file"))
dat <- read.csv(file$datapath, header = input$header)
}
dat
})
}
shinyApp(ui, server)
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