在 JSON.NET 中序列化派生类时的字段顺序

根据JSON standard，JSON对象是unordered set of name/value pairs.所以我的建议是不要担心财产秩序.不过，您可以通过创建自己的ContractResolver来获得所需的顺序，该ContractResolver继承自标准contract resolvers之一，然后覆盖CreateProperties:

public class BaseFirstContractResolver : DefaultContractResolver
{
    protected override IList<JsonProperty> CreateProperties(Type type, MemberSerialization memberSerialization) =>
        base.CreateProperties(type, memberSerialization)
            ?.OrderBy(p => p.DeclaringType.BaseTypesAndSelf().Count()).ToList();
}

public static class TypeExtensions
{
    public static IEnumerable<Type> BaseTypesAndSelf(this Type type)
    {
        while (type != null)
        {
            yield return type;
            type = type.BaseType;
        }
    }
}

然后像这样使用它:

// Cache an instance of the resolver for performance
static IContractResolver baseFirstResolver = new BaseFirstContractResolver { /* Set any required properties here e.g.  NamingStrategy = new CamelCaseNamingStrategy() */ };

// And use the cached instance when serializing and deserializing
var settings = new JsonSerializerSettings 
{ 
    ContractResolver = baseFirstResolver, 
    // Add your other settings here.
    TypeNameHandling = TypeNameHandling.Objects 
};
var json = JsonConvert.SerializeObject(derived, typeof(Base), Formatting.Indented, settings);

注:

• 这种方法尤其适用于多级类型层次 struct ，因为它可以自动对层次 struct 中所有级别的属性进行正确排序

• Newtonsoft推荐caching instances of contract resolvers%的最佳性能

演示小提琴here.