测试 R Shiny 中一组编号的输入对象中的任何输入是否为空 [英] Test whether any input in a set of numbered input objects in R Shiny is empty

问题描述

假设我为多图导出创建了 10 个 selectInput 下拉菜单，这些 selectInputs 被称为xaxis_1"、xaxis_2"、..... 、"xaxis_10"

Let's say I have created 10 selectInput dropdowns for a multi plot export and these selectInputs are called "xaxis_1", "xaxis_2", ..... , "xaxis_10"

对于单个 1 我可以写:if(!is.null(input$xaxis_1)) { .... do stuff } 当用户没有输入任何名称并按下提交时停止它运行导出，以避免崩溃.

for a single 1 I can write: if(!is.null(input$xaxis_1)) { .... do stuff } to stop it running export when the user hasn't entered any name, and presses submit, to avoid crashes.

更一般的你可以检查一下:

A bit more general you can check this:

if(!is.null(input[[paste('xaxis', i, sep = '_')]])) { ...}

如何优雅地编写它，以便 1 行代码检查 1:10 输入 [[...]] 中的任何一个是否为空，即 NULL?

how can you write it elegantly so that 1 line of code checks whether ANY of the 1:10 input[[...]] is empty, i.e. NULL?

输入的 nr 取决于用户想要导出每个文件的图数，所以所有都是用 lapply(1:input$nrofplots, function(i) { .... } renderUI 结构，而我的 if 语句需要具有 1:n 一样的灵活性

The nr of inputs depends on how many plots the user wants to export per file, so all is build with lapply(1:input$nrofplots, function(i) { .... } renderUI structure, and my if statement needs to have the same flexibility of 1:n

在如下图所示的情况下，按 Initiate export 应该给出一个 sweetalert(知道了)说至少缺少 1 个值

In a situation like below in the image, pressing Initiate export should give a sweetalert (got that covered) saying there is at least 1 value missing

推荐答案

这里是我在 UI 端用来验证用户输入的一个片段.

Here a snippet I used in the UI side to validate the user's inputs.

library(shiny)
library(shinyjs)

ui <- fluidPage(
 useShinyjs(),  # Set up shinyjs
 numericInput('axis1','Val 1',1),
 numericInput('axis2','Val 2',1),
 numericInput('axis3','Val 3',1),
 actionButton('Go','Plot')
)

server <- function(input, output, session) {
  #Try 1, space, AAA and check what shiny will return
  observe(print(input$axis1))
  observe({
    All_Inputs <- vapply(paste0('axis',1:3),
                                function(x){isTruthy(input[[x]])},
                                logical(1))
    All_InputsCP <- all(All_Inputs)
    shinyjs::toggleState(id="Go", condition = All_InputsCP) #This is to make the button Go able or disable according to condition All_InputsCP #
  })
}

shinyApp(ui, server)

希望能帮到你.

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