// By manipulating the list of node deserializers,

// it is easy to add behavior to the deserializer.

// This example shows how to validate the objects as they are deserialized.

​

using System;

using System.IO;

using System.Linq;

using System.ComponentModel.DataAnnotations;

using YamlDotNet.Core;

using YamlDotNet.Serialization;

using YamlDotNet.Serialization.NodeDeserializers;

​

// First, we'll implement a new INodeDeserializer

// that will decorate another INodeDeserializer with validation:

public class ValidatingNodeDeserializer : INodeDeserializer

{

    private readonly INodeDeserializer _nodeDeserializer;

​

    public ValidatingNodeDeserializer(INodeDeserializer nodeDeserializer)

    {

        _nodeDeserializer = nodeDeserializer;

    }

​

    public bool Deserialize(EventReader reader, Type expectedType,

        Func<EventReader, Type, object> nestedObjectDeserializer,

        out object value)

    {

        if (_nodeDeserializer.Deserialize(reader, expectedType,

            nestedObjectDeserializer, out value))

        {

            var context = new ValidationContext(value, null, null);

            Validator.ValidateObject(value, context, true);

            return true;

        }

        return false;

    }

}

​

public class Program

{

    public static void Main()

    {

        // Then we wrap the existing ObjectNodeDeserializer

        // with our ValidatingNodeDeserializer:

        var deserializer = new Deserializer();

​

        var objectDeserializer = deserializer.NodeDeserializers

            .Select((d, i) => new {

                Deserializer = d as ObjectNodeDeserializer,

                Index = i

            })

            .First(d => d.Deserializer != null);

        deserializer.NodeDeserializers[objectDeserializer.Index] =

            new ValidatingNodeDeserializer(objectDeserializer.Deserializer);

        // This will fail with a validation exception

        deserializer.Deserialize<Data>(new StringReader(@"Name: ~"));

    }

}

​

public class Data

{

    [Required]

    public string Name { get; set; }

}

​