如何测试上传的Excel文件是否符合要求

Question

背景

假设我有一个shiny 应用程序，用户可以在其中上传 Excel 文件。用户将有权访问某个 Excel 模板，我想确保只上传此模板的副本。

我目前的做法

我现在的做法如下：

1. 检查工作表名称 xyz 是否存在 -> 如果不存在则抛出错误
2. 从工作表 xyz 中读取数据，将列名与要求进行比较 -> 如果缺少列会引发错误
3. 重复所有必要的工作表

当前方法存在问题

这需要对所需的工作表名称和所需的列名称进行大量硬编码，并且变得乏味。

问题

所以我的问题是：如何确保用户提供有效文件？您通常使用什么策略来确保您的应用可以正确处理上传的文件？

---

伪代码

library(shiny)
library(tidyverse)
ui <- fluidPage(fileInput("file", "Upload Excel"))
server <- function(input, output, session) {
    observe({
      req(input$file)
      sheet1 <- tryCatch(read_xlsx(input$file$datapath, sheet = "xyz"),
          error = function(e) {
             ## do some sort of error handling, e.g. write to a reactiveValue list
          })
      if (!all(.REQUIRED_FIELDS_FOR_XYZ %in% names(sheet1))) {
          ## signal error
      }
    })
}

Answer 1

如果您已经在使用 Excel，为什么不使用宏来为您完成工作。考虑列出文件路径、检查格式类型、单元格地址、单元格值等。下面的宏将为您完成大部分繁重的工作。

Sub GetFolder_Data_Collection()

    Dim colFiles As Collection, c As Range
    Dim strPath As String, f, sht As Worksheet
    Dim wbSrc As Workbook, wsSrc As Worksheet
    Dim rw As Range
    Dim sh As Worksheet, flg As Boolean

    Set sht = ActiveSheet

    strPath = ThisWorkbook.Path

    Set colFiles = GetFileMatches(strPath, "*.xlsx", True)

    With sht
        .Range("A:I").ClearContents
        .Range("A1").Resize(1, 5).Value = Array("Name", "Path", "Cell", "Value", "Numberformat")
        Set rw = .Rows(2)
    End With

    For Each f In colFiles
        Set wbSrc = Workbooks.Open(f)
        Set wsSrc = wbSrc.Sheets(1)
        For Each c In wsSrc.Range(wsSrc.Range("A1"), _
                                  wsSrc.Cells(1, Columns.Count).End(xlToLeft)).Cells


            rw.Cells(2).Value = wbSrc.Path
            sht.Hyperlinks.Add Anchor:=rw.Cells(1), Address:=wbSrc.Path, TextToDisplay:=wbSrc.Name
            rw.Cells(3).Value = c.Address(False, False)
            rw.Cells(4).Value = c.Value
            rw.Cells(5).Value = c.NumberFormat

            i = 6
            For Each sh In Worksheets
                If sh.Name Like "Sheet1*" Or sh.Name Like "*Sheet2*" Then rw.Cells(i).Value = sh.Name & " Exists"
                i = i + 1
            Next


            Set rw = rw.Offset(1, 0)
        Next c
        wbSrc.Close False
    Next f
End Sub


'Return a collection of file objects given a starting folder and a file pattern
'  e.g. "*.txt"
'Pass False for last parameter if don't want to check subfolders
Function GetFileMatches(startFolder As String, filePattern As String, _
                    Optional subFolders As Boolean = True) As Collection

    Dim fso, fldr, f, subFldr
    Dim colFiles As New Collection
    Dim colSub As New Collection

    Set fso = CreateObject("scripting.filesystemobject")
    colSub.Add startFolder

    Do While colSub.Count > 0
        Set fldr = fso.GetFolder(colSub(1))
        colSub.Remove 1

        For Each f In fldr.Files
            If UCase(f.Name) Like UCase(filePattern) Then colFiles.Add f
        Next f
        If subFolders Then
            For Each subFldr In fldr.subFolders
                colSub.Add subFldr.Path
            Next subFldr
        End If
    Loop
    Set GetFileMatches = colFiles
End Function

将此代码放入 XLSB 或 XLSM EXCEL 文件中，与您的 EXCEL 文件位于同一文件夹中。

使用 Excel 做这种事情可能更容易，而且我非常支持使用正确的工具来完成这项工作。