AppleScript——检查文件是否存在不起作用

Question

出于某种原因，当我检查文件是否存在时，它总是返回 true:

display dialog (exists (homePath & "Desktop/11-14.csv" as POSIX file as string))

无论我的桌面上是否有一个名为它的 csv，它都会返回 true。我想创建一个通过文件存在工作的 if 函数，但是因为它总是返回为真，所以它搞砸了我的 if 函数。我能做些什么来解决这个问题？

Answer 1

一些解释:它总是返回true的原因是文件类存在而不是驱动器上的文件。就像说存在“Hello World!”一样。它总是返回 true，因为字符串 "Hello World!"确实存在。默认情况下，exists 命令只检查给定值是否为缺失值。当它缺少值时返回false，否则返回true。但是，有些应用程序会覆盖标准存在命令，例如 System Events 和 Finder。因此，要对文件使用存在命令并想要检查文件是否存在，您应该将代码包装在告诉应用程序“系统事件”或“查找器” block 中，就像在 adayzdone 示例代码中一样。

有更多方法可以剥这只猫的皮。

set theFile to "/Users/wrong user name/Desktop"

--using system events 
tell application "System Events" to set fileExists to exists disk item (my POSIX file theFile as string)

--using finder
tell application "Finder" to set fileExists to exists my POSIX file theFile

--using alias coercion with try catch
try
    POSIX file theFile as alias
    set fileExists to true
on error
    set fileExists to false
end try

--using a do shell script
set fileExists to (do shell script "[ -e " & quoted form of theFile & " ] && echo true || echo false") as boolean

--do the actual existence check yourself
--it's a bit cumbersome but gives you an idea how an file check actually works
set AppleScript's text item delimiters to "/"
set pathComponents to text items 2 thru -1 of theFile
set AppleScript's text item delimiters to ""
set currentPath to "/"
set fileExists to true
repeat with component in pathComponents
    if component is not in every paragraph of (do shell script "ls " & quoted form of currentPath) then
        set fileExists to false
        exit repeat
    end if
    set currentPath to currentPath & component & "/"
end repeat
return fileExists