c# - 使用谓词列表时出现 DataContract SerializationException

Question

我正在编写一个通用过滤器类，主要用于从人群中过滤人员。我正在尝试序列化过滤器类，但在运行时我得到一个 SerializationException:

System.Runtime.Serialization.SerializationException : Type 'System.DelegateSerializationHolder+DelegateEntry' with data contract name 'DelegateSerializationHolder.DelegateEntry:http://schemas.datacontract.org/2004/07/System' is not expected. Consider using a DataContractResolver or add any types not known statically to the list of known types - for example, by using the KnownTypeAttribute attribute or by adding them to the list of known types passed to DataContractSerializer.

我的过滤器类如下所示:

[DataContract(Name = "Filter", Namespace = "")]
    public class Filter<T>
    {

        /// <summary>
        /// Default constructor, needed by serializers.
        /// </summary>
        public Filter()
        {
            Name = "New filter";
            Predicates = new List<Predicate<T>>();
        }

        /// <summary>
        /// ctor. Takes a list of predicates for type T
        /// to filter with.  
        /// </summary>
        public Filter(string name, IEnumerable<Predicate<T>> predicates)
        {
            Name = name;
            Predicates = predicates.ToList();
        }

        /// <summary>
        /// Name of the filter. 
        /// </summary>
        [DataMember(Order = 0)]
        public string Name
        {
            get;
            set;
        }

        [DataMember(Order = 1)]
        public List<Predicate<T>> Predicates
        {
            get;
            set;
        }

        /// <summary>
        /// Filters sequence of type T. 
        /// </summary>
        public IEnumerable<T> ApplyFilter(IEnumerable<T> input)
        {
            var result = new List<T>(input);
            return Predicates.Aggregate(result, (current, predicate) => current.FindAll(predicate));
        }
    }

当序列化过滤器类时，出现上述异常。如果我不将 Predicate 标记为 DataMember，那么它就可以工作。但显然我也想序列化该属性。

我已经处理这个问题几个小时了，但我想不通。任何帮助将不胜感激!

Answer 1

DataContractSerializer 不适用于序列化委托(delegate)；多播委托(delegate)是一组任意目标对象和方法；这不是一个明确定义的面向数据的契约。 DataContractSerializer 用于数据。

要么将某种形式的表达式序列化为字符串(或某种简单的树)，要么使用不同的序列化程序。