如何为可能为空的对象执行 ToString? [英] How to do ToString for a possibly null object?

问题描述

是否有一种简单的方法可以执行以下操作:

Is there a simple way of doing the following:

String s = myObj == null ? "" : myObj.ToString();

我知道我可以执行以下操作，但我真的认为这是一种黑客行为:

I know I can do the following, but I really consider it as a hack:

String s = "" + myObj;

如果 Convert.ToString() 对此有适当的重载，那就太好了.

It would be great if Convert.ToString() had a proper overload for this.

推荐答案

C# 6.0

使用 C# 6.0，我们现在可以拥有原始方法的简洁、免转换版本:

With C# 6.0 we can now have a succinct, cast-free version of the orignal method:

string s = myObj?.ToString() ?? "";

甚至使用插值:

string s = $"{myObj}";

原答案:

string s = (myObj ?? String.Empty).ToString();

或

string s = (myObjc ?? "").ToString()

更简洁.

不幸的是，正如已经指出的那样，您通常需要在任一侧进行强制转换才能使其与非 String 或 Object 类型一起使用:

Unfortunately, as has been pointed out you'll often need a cast on either side to make this work with non String or Object types:

string s = (myObjc ?? (Object)"").ToString()
string s = ((Object)myObjc ?? "").ToString()

因此，虽然看起来很优雅，但演员阵容几乎总是必要的，而且在实践中并不那么简洁.

Therefore, while it maybe appears elegant, the cast is almost always necessary and is not that succinct in practice.

正如其他地方所建议的，我建议使用扩展方法来使这个更简洁:

As suggested elsewhere, I recommend maybe using an extension method to make this cleaner:

public static string ToStringNullSafe(this object value)
{
    return (value ?? string.Empty).ToString();
}

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