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POProtoBuf-net AsReference require public constructor in Activator.CreateInstance?
 

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    <p>While working on 2 of my classes that looks like this (minimal)</p> <pre><code>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&lt;Child&gt;() { 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&lt;Family&gt;(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&lt;Child&gt; m_Children; /// &lt;summary&gt; /// ProtoBuf deserialization constructor (fails here) /// &lt;/summary&gt; private Parent() { m_Children = new List&lt;Child&gt;(); } public Parent(List&lt;Child&gt; children) { m_Children = children; m_Children.ForEach(x =&gt; x.Parent = this); } } [ProtoContract()] public class Family { [ProtoMember(1)] protected List&lt;Parent&gt; m_Parents; public void Add(Parent parent) { m_Parents.Add(parent); } public Family() { m_Parents = new List&lt;Parent&gt;(); } } } </code></pre> <p>During deserialization, I encounter the exception "No parameterless constructor defined for this object." for creating the Parent object in ProtoBuf.BclHelper near</p> <pre><code>case FieldObject: // ... value = ((options &amp; NetObjectOptions.UseConstructor) == 0) ? BclHelpers.GetUninitializedObject(type) : Activator.CreateInstance(type); </code></pre> <p>Then when I changed the default constructor Parent() to public, the exception goes away.</p> <p>Any idea what <strike>I may have overlooked</strike> is the correct usage for AsRerference in this case?</p> <p><strong>BOUNTY</strong>: While Marc takes his time to fix the issue, I would require a definitive solution to use protobuf-net in this situation, working around either by protobuf-net attributes, methods or other tricks. Otherwise I will have to abandon the use of protobuf-net altogether. Thanks for any help.</p>
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    1. COI've just returned from a few days away. I will look at this later.
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    2. COLooking at this briefly, I think there is an edge case relating to inheritance and reference-tracking; I know how to resolve it - it just needs a few tweaks to fix.
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    3. CO@Marc Thanks for being here. Really apprecatiate your contributions. If you ever get time to have this sorted hopefully you will update the answer here. Thanks again.
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