CA2229: Implement serialization constructors







Breaking Change

Non Breaking

The type implements the ISerializable interface, is not a delegate or interface, and one of the following conditions is true:

  • The type does not have a constructor that takes a SerializationInfo object and a StreamingContext object (the signature of the serialization constructor).

  • The type is unsealed and the access modifier for its serialization constructor is not protected (family).

  • The type is sealed and the access modifier for its serialization constructor is not private.

This rule is relevant for types that support custom serialization. A type supports custom serialization if it implements the ISerializable interface. The serialization constructor is required to deserialize, or re-create objects that have been serialized using the ISerializable.GetObjectData method.

To fix a violation of this rule, implement the serialization constructor. For a sealed class, make the constructor private; otherwise, make it protected.

Do not suppress a violation of the rule. The type will not be deserializable, and will not function in many scenarios.

The following example shows a type that satisfies the rule.

using System;
using System.IO;
using System.Runtime.Serialization;
using System.Runtime.Serialization.Formatters.Binary;
using System.Security.Permissions;

namespace UsageLibrary 
    public class SerializationConstructorsRequired : ISerializable 
        private   int n1;

        // This is a regular constructor. 
        public SerializationConstructorsRequired ()
            n1 = -1;
        // This is the serialization constructor. 
        // Satisfies rule: ImplementSerializationConstructors. 

        protected SerializationConstructorsRequired(
           SerializationInfo info, 
           StreamingContext context)
            n1 = (int) info.GetValue("n1", typeof(int));

        // The following method serializes the instance.
        void ISerializable.GetObjectData(SerializationInfo info, 
           StreamingContext context)
            info.AddValue("n1", n1);