Newtonsoft.Json\Converters\EntityKeyMemberConverter.cs

#region License

// Copyright (c) 2007 James Newton-King

//

// Permission is hereby granted, free of charge, to any person

// obtaining a copy of this software and associated documentation

// files (the "Software"), to deal in the Software without

// restriction, including without limitation the rights to use,

// copy, modify, merge, publish, distribute, sublicense, and/or sell

// copies of the Software, and to permit persons to whom the

// Software is furnished to do so, subject to the following

// conditions:

//

// The above copyright notice and this permission notice shall be

// included in all copies or substantial portions of the Software.

//

// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,

// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES

// OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND

// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT

// HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,

// WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING

// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR

// OTHER DEALINGS IN THE SOFTWARE.

#endregion

#if !PocketPC && !SILVERLIGHT && !NET20

using System;

using Newtonsoft.Json.Serialization;

using System.Globalization;

using Newtonsoft.Json.Utilities;

namespace Newtonsoft.Json.Converters

{

  internal interface IEntityKeyMember

  {

    string Key { get; set; }

    object Value { get; set; }

  }

  /// <summary>

  /// Converts an Entity Framework EntityKey to and from JSON.

  /// </summary>

  public class EntityKeyMemberConverter : JsonConverter

  {

    private const string EntityKeyMemberFullTypeName = "System.Data.EntityKeyMember";

    /// <summary>

    /// Writes the JSON representation of the object.

    /// </summary>

    /// <param name="writer">The <see cref="JsonWriter"/> to write to.</param>

    /// <param name="value">The value.</param>

    /// <param name="serializer">The calling serializer.</param>

    public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)

    {

      IEntityKeyMember entityKeyMember = DynamicWrapper.CreateWrapper<IEntityKeyMember>(value);

      Type keyType = (entityKeyMember.Value != null) ? entityKeyMember.Value.GetType() : null;

      writer.WriteStartObject();

      writer.WritePropertyName("Key");

      writer.WriteValue(entityKeyMember.Key);

      writer.WritePropertyName("Type");

      writer.WriteValue((keyType != null) ? keyType.FullName : null);

      writer.WritePropertyName("Value");

      if (keyType != null)

      {

        string valueJson;

        if (JsonSerializerInternalWriter.TryConvertToString(entityKeyMember.Value, keyType, out valueJson))

          writer.WriteValue(valueJson);

        else

          writer.WriteValue(entityKeyMember.Value);

      }

      else

      {

        writer.WriteNull();

      }

      writer.WriteEndObject();

    }

    private static void ReadAndAssertProperty(JsonReader reader, string propertyName)

    {

      ReadAndAssert(reader);

      if (reader.TokenType != JsonToken.PropertyName || reader.Value.ToString() != propertyName)

        throw new JsonSerializationException("Expected JSON property '{0}'.".FormatWith(CultureInfo.InvariantCulture, propertyName));

    }

    private static void ReadAndAssert(JsonReader reader)

    {

      if (!reader.Read())

        throw new JsonSerializationException("Unexpected end.");

    }

    /// <summary>

    /// Reads the JSON representation of the object.

    /// </summary>

    /// <param name="reader">The <see cref="JsonReader"/> to read from.</param>

    /// <param name="objectType">Type of the object.</param>

    /// <param name="existingValue">The existing value of object being read.</param>

    /// <param name="serializer">The calling serializer.</param>

    /// <returns>The object value.</returns>

    public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)

    {

      IEntityKeyMember entityKeyMember = DynamicWrapper.CreateWrapper<IEntityKeyMember>(Activator.CreateInstance(objectType));

      ReadAndAssertProperty(reader, "Key");

      ReadAndAssert(reader);

      entityKeyMember.Key = reader.Value.ToString();

      ReadAndAssertProperty(reader, "Type");

      ReadAndAssert(reader);

      string type = reader.Value.ToString();

      Type t = Type.GetType(type);

      ReadAndAssertProperty(reader, "Value");

      ReadAndAssert(reader);

      entityKeyMember.Value = serializer.Deserialize(reader, t);

      ReadAndAssert(reader);

      return DynamicWrapper.GetUnderlyingObject(entityKeyMember);

    }

    /// <summary>

    /// Determines whether this instance can convert the specified object type.

    /// </summary>

    /// <param name="objectType">Type of the object.</param>

    /// <returns>

    /// 	<c>true</c> if this instance can convert the specified object type; otherwise, <c>false</c>.

    /// </returns>

    public override bool CanConvert(Type objectType)

    {

      return (objectType.AssignableToTypeName(EntityKeyMemberFullTypeName));

    }

  }

}

#endif