C#:在尝试从另一个程序集中使用它之前,如何确保设置变量存在？

Question

我有以下内容:

using CommonSettings = MyProject.Commons.Settings;

public class Foo
{
    public static void DoSomething(string str)
    {
        //How do I make sure that the setting exists first?
        object setting = CommonSettings.Default[str];

        DoSomethingElse(setting);
    }
}

Answer 1

如果您正在使用a SettingsPropertyCollection,则必须循环并检查自己存在哪些设置,因为它没有任何Contains方法.

private bool DoesSettingExist(string settingName)
{
   return Properties.Settings.Default.Properties.Cast<SettingsProperty>().Any(prop => prop.Name == settingName);
}

Answer 2

根据类型CommomSettings.Default,简单的空检查应该没问题:

if(setting != null)
    DoSomethingElse(setting);

如果要在尝试检索设置之前检查,则需要发布CommonSettings.Default类型.它看起来像一个字典,所以你可以逃脱:

if(CommonSettings.Default.ContainsKey(str))
{
    DoSomethingElse(CommonSettings.Default[str]);
}

Answer 3

try
{
    var x = Settings.Default[bonusMalusTypeKey]);
}
catch (SettingsPropertyNotFoundException ex)
{
    // Ignore this exception (return default value that was set)
}

Answer 4

这是你如何处理它:

if(CommonSettings.Default.Properties[str] != null)
{
    //Hooray, we found it!
}
else
{
    //This is a 'no go'
}