表达式树不能包含“is”模式匹配运算符

Question

我正在尝试使用

Automapper

来映射这些属性

public class SourceClass
{
    public object emailNotification { get; set; }
}

public class DestinationClass
{
    public int emailNotificationId { get; set; }
    public string emailNotificationLookupName { get; set; }
}

当我调试它时，

emailNotification

=

ValueKind = Object : "{ "id": 3, "lookupName": "Send Email Notification" }"

。

预期结果是

• 电子邮件通知 ID = 3
• emailNotificationLookupName =“发送电子邮件通知”

这是我当前的映射代码，但我有这个编译错误：

An expression tree may not contain an 'is' pattern-matching operator.

in

src.emailNotification is JObject jObject

public class SourceProfile : AutoMapper.Profile
{
    public SourceProfile()
    {
        CreateMap<SourceClass, DestinationClass>()     
            .ForMember(dest => dest.emailNotificationId, opt => opt.MapFrom(src =>
                src.emailNotification != null && src.emailNotification is JObject jObject ? jObject["id"].Value<int>() : 0))
            .ForMember(dest => dest.emailNotificationLookupName, opt => opt.MapFrom(src =>
                src.emailNotification != null && src.emailNotification is JObject jObject ? jObject["lookupName"].Value<string>() : null))
        ;
                        
    }
}

Answer 1

您可以使用

as

运算符替换

is

来解决问题

CreateMap<SourceClass, DestinationClass>()     
    .ForMember(dest => dest.emailNotificationId, opt => opt.MapFrom(src =>
        src.emailNotification != null && (src.emailNotification as JObject) != null ? (src.emailNotification as JObject)["id"].Value<int>() : 0))
    .ForMember(dest => dest.emailNotificationLookupName, opt => opt.MapFrom(src =>
        src.emailNotification != null && (src.emailNotification as JObject) != null ? (src.emailNotification as JObject)["lookupName"].Value<string>() : null))

由于验证

emailNotification

的逻辑不是

null

并且必须在多个位置重复

JObject

，因此您可以考虑迁移

AfterMap

操作中的逻辑：

CreateMap<SourceClass, DestinationClass>()     
    .AfterMap((src, dest, context) =>
    {
        if (src.emailNotification != null && src.emailNotification is JObject jObject)
        {
            dest.emailNotificationId = jObject["id"].Value<int>();
            dest.emailNotificationLookupName = jObject["lookupName"].Value<string>();
        }
    });