// 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;

    }

}