AutoMapper TypeConverter将可空类型映射到不可空类型 [英] AutoMapper TypeConverter mapping nullable type to not-nullable type

问题描述

我正在使用AutoMapper，我已经注册了一个TypeConverter将可空的长值映射为长整型值，例如：

I'm using AutoMapper, and I've registered a TypeConverter to map nullable long values to long values like so:

public class NullableLongToLongConverter : TypeConverter<long?, long>
{
    protected override long ConvertCore(long? source)
    {
        return source ?? 0;
    }
}

此操作正常，并自动选择任何可空的长

This works fine, and automatically picks up any nullable longs being converted to longs.

但是，我还有一些其他地图想要将可空的longs转换为可空的longs。这些也最终使用这种类型的转换器。例如，两个属性在下面的代码中被设置为0，但是我希望NullableLong被设置为null。我做错了什么？

However, I've got some other maps which want to 'convert' nullable longs to nullable longs. These also end up using this type converter. For example, both properties are getting set to 0 in the code below, but I'd expect NullableLong to be set to null. Am I doing something wrong?

public class Foo
{
    public long? NullableLong{get {return null;}}
    ......
}

public class Bar
{
    public long NotNullableLong{get;set;}
    public long? NullableLong{get;set;}
    ......
}

public static class ComplicatedMapRegister
{
    public static void RegisterMap()
    {
        Mapper.CreateMap<Foo, Bar>()
            .ForMember(b => b.NotNullableLong, opt => opt.MapFrom(f.NullableLong))
            .ForMember(b => b.NullableLong, opt => opt.MapFrom(f.NullableLong))
            .....
    }
}

public static class AutoMapperRegistration
{
    public static void RegisterAllMaps()
    {
        Mapper.CreateMap<long?, long>().ConvertUsing<NullableLongToLongConverter>();
        ComplicatedMapRegister.RegisterMap();
    }
}

推荐答案

只有注册了一个转换器，从 long？映射到 long 。你不是只需要创建并注册一个从 long？映射到 long？的转换器？

You've only registered a converter that maps from long? to long. Don't you just need to create and register a 'converter' that will map from long? to long??

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