C# 在Guid上转换为泛型类型失败

我试图更改对象属性的类型，当我使用它时，它不会将字符串转换为guid，当我查找时，我发现如果guid是可空的，它将不会通过，所以我跟随了一篇文章，解释了默认方法不适用于可空的，我唯一无法修复的是将x值转换为y实体类型，知道x是字符串，y是guid

自定义更改类型类以跳过可为空的问题

public static object ChangeType(object value, Type conversionType)
    {
        // Note: This if block was taken from Convert.ChangeType as is, and is needed here since we're
        // checking properties on conversionType below.
        if (conversionType == null)
        {
            throw new ArgumentNullException("conversionType");
        } // end if

        // If it's not a nullable type, just pass through the parameters to Convert.ChangeType

        if (conversionType.IsGenericType &&
          conversionType.GetGenericTypeDefinition().Equals(typeof(Nullable<>)))
        {
            // It's a nullable type, so instead of calling Convert.ChangeType directly which would throw a
            // InvalidCastException (per http://weblogs.asp.net/pjohnson/archive/2006/02/07/437631.aspx),
            // determine what the underlying type is
            // If it's null, it won't convert to the underlying type, but that's fine since nulls don't really
            // have a type--so just return null
            // Note: We only do this check if we're converting to a nullable type, since doing it outside
            // would diverge from Convert.ChangeType's behavior, which throws an InvalidCastException if
            // value is null and conversionType is a value type.
            if (value == null)
            {
                return null;
            } // end if

            // It's a nullable type, and not null, so that means it can be converted to its underlying type,
            // so overwrite the passed-in conversion type with this underlying type
            NullableConverter nullableConverter = new NullableConverter(conversionType);
            conversionType = nullableConverter.UnderlyingType;
        } // end if

        // Now that we've guaranteed conversionType is something Convert.ChangeType can handle (i.e. not a
        // nullable type), pass the call on to Convert.ChangeType

        return Convert.ChangeType(value, conversionType);
    }

(T)TypeDescriptor.GetConverter(typeof(T)).ConvertFromInvariantString(text);
(instance.GetType())TypeDescriptor.GetConverter(instance.GetType().).ConvertFromInvariantString(text);

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如果试图将字符串转换为GUID，为什么不将其传递给GUID构造函数（例如，{GUID temp=new GUID（stringValue）}？如果字符串为空，则创建一个空GUID。

那么问题是什么？使用convert.changeType（value，type）如果你真的尝试自己编写代码，那么为什么不将你的尝试包含在问题中。目前，你的问题没有证据表明你已经尝试过，因此将被否决和关闭。你甚至没有提出任何问题。不要只是陈述你的问题和答案暗示问题。直截了当地问问题。好吧，我将发布我所使用的内容。我希望现在这足够证明类型是泛型的，所以它不能是新的Guid（字符串），但是如果知道需要从字符串转到泛型中的Guid，则将遗传转换为字符串并创建Guid。