Win32_Product InstallLocation(错误) [英] Win32_Product InstallLocation (error)

问题描述

在 C# 中，我试图从 Win32_Product 的实例中获取一些属性，但我似乎有一个错误提示对象引用未设置到对象的实例."

in C#, i'm trying to get some properties from the instances of Win32_Product, but i seem to have an error saying "Object reference not set to an instance of an object."

代码如下:

class Package {
 public string productName;
 public string installDate;
 public string installLocation;
}

class InstalledPackages
{
    public static List<Package> get()
    {
        List<Package> packages = new List<Package>();
        string query = "SELECT * FROM Win32_Product";
        ManagementScope oMs = new ManagementScope();
        ObjectQuery oQuery = new ObjectQuery(query);
        ManagementObjectSearcher oSearcher = new ManagementObjectSearcher(oMs, oQuery);
        ManagementObjectCollection installedPackages = oSearcher.Get();
        foreach (ManagementObject package in installedPackages)
        {
            Package p = new Package();
            p.productName = package["Name"].ToString();
            p.installLocation = package["InstallLocation"].ToString();
            p.installDate = package["InstallDate"].ToString();
            packages.Add(p);
        }
        return packages;
    }
}

到达时出现异常

p.installLocation = package["InstallLocation"].ToString();

此外，如果我尝试这样做，我会得到一个

also, i get one if i try to do

p.installLocation = package["InstallDate2"].ToString();

如果我要求 InstallDate 它可以工作.

if i'm asking for InstallDate it works.

(我使用的是 Windows 7 Ultimate x64)

(i'm using Windows 7 Ultimate x64)

推荐答案

基于运行

gwmi -Class Win32_Product -Property Name,InstallLocation,InstallDate | ft Name,InstallLocation,InstallDate

在 PowerShell 中，InstallLocation 在许多情况下似乎为空.用空检查替换问题行应该可以解决问题.

in PowerShell, it appears that InstallLocation is null in many cases. Replacing the problem line with a check for null should fix the problem.

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