c# - ProtoBuf-net AsReference 需要 Activator.CreateInstance 中的公共(public)构造函数吗？

Question

在我的 2 个类中工作时看起来像这样(最小)

using System;
using System.Collections.Generic;
using System.Collections;
using System.ComponentModel;
using System.Drawing;
using System.Windows.Forms;
using System.IO;
using ProtoBuf;

namespace Sandbox
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            Family family = new Family();
            Child child1 = new Child(1);
            Child child2 = new Child(2);
            Parent parent = new Parent(new List<Child>() { child1, child2 });
            family.Add(parent);

            string file = "sandbox.txt";

            try { File.Delete(file); } catch { }

            using (var fs = File.OpenWrite(file)) { Serializer.Serialize(fs, family); }
            using (var fs = File.OpenRead(file)) { family = Serializer.Deserialize<Family>(fs); }

            System.Diagnostics.Debug.Assert(family != null, "1. Expect family not null, but not the case.");
        }
    }

    [ProtoContract()]
    public class Child
    {
        [ProtoMember(1, AsReference = true)]
        internal Parent Parent;

        private Child() { }

        public Child(int i) { }
    }

    [ProtoContract()]
    public class Parent
    {
        [ProtoMember(1)]
        protected List<Child> m_Children;

        /// <summary>
        /// ProtoBuf deserialization constructor (fails here)
        /// </summary>
        private Parent() { m_Children = new List<Child>(); }

        public Parent(List<Child> children)
        {
            m_Children = children;
            m_Children.ForEach(x => x.Parent = this);
        }
    }

    [ProtoContract()]
    public class Family
    {
        [ProtoMember(1)]
        protected List<Parent> m_Parents;

        public void Add(Parent parent)
        {
            m_Parents.Add(parent);
        }

        public Family()
        {
            m_Parents = new List<Parent>();
        }
    }
}

在反序列化过程中，我遇到异常“No parameterless constructor defined for this object”。用于在附近的 ProtoBuf.BclHelper 中创建 Parent 对象

case FieldObject:
// ...
value = ((options & NetObjectOptions.UseConstructor) == 0) ? BclHelpers.GetUninitializedObject(type) : Activator.CreateInstance(type);

然后当我将默认构造函数 Parent() 更改为 public 时，异常消失了。

知道 我可能忽略了 在这种情况下 AsRerference 的正确用法吗？

赏金:虽然 Marc 花时间解决了这个问题，但我需要一个明确的解决方案来在这种情况下使用 protobuf-net，通过 protobuf-net 属性、方法或其他技巧来解决。否则我将不得不完全放弃使用 protobuf-net。感谢您的帮助。

Answer 1

我相信你可以这样做来解决这个问题:

[ProtoContract(SkipConstructor = true)]
public class Parent
{
    [ProtoMember(1)]
    protected List<Child> m_Children;

    private Parent() { Initialize(); }

    [ProtoBeforeDeserialization] // could also use OnDeserializing
    private void Initialize()
    {
        m_Children = new List<Child>();
    }

    public Parent(List<Child> children)
    {
        m_Children = children;
        m_Children.ForEach(x => x.Parent = this);
    }