Newtonsoft.Json\Converters\StringEnumConverter.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

using System;

using System.Globalization;

using Newtonsoft.Json.Utilities;

namespace Newtonsoft.Json.Converters

{

  /// <summary>

  /// Converts an <see cref="Enum"/> to and from its name string value.

  /// </summary>

  public class StringEnumConverter : JsonConverter

  {

    /// <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)

    {

      if (value == null)

      {

        writer.WriteNull();

        return;

      }

      Enum e = (Enum) value;

      string enumName = e.ToString("G");

      if (char.IsNumber(enumName[0]) || enumName[0] == '-')

        writer.WriteValue(value);

      else

        writer.WriteValue(enumName);

    }

    /// <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)

    {

      Type t = (ReflectionUtils.IsNullableType(objectType))

        ? Nullable.GetUnderlyingType(objectType)

        : objectType;

      if (reader.TokenType == JsonToken.Null)

      {

        if (!ReflectionUtils.IsNullableType(objectType))

          throw new Exception("Cannot convert null value to {0}.".FormatWith(CultureInfo.InvariantCulture, objectType));

        return null;

      }

      if (reader.TokenType == JsonToken.String)

        return Enum.Parse(t, reader.Value.ToString(), true);

      if (reader.TokenType == JsonToken.Integer)

        return ConvertUtils.ConvertOrCast(reader.Value, CultureInfo.InvariantCulture, t);

      throw new Exception("Unexpected token when parsing enum. Expected String or Integer, got {0}.".FormatWith(CultureInfo.InvariantCulture, reader.TokenType));

    }

    /// <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)

    {

      Type t = (ReflectionUtils.IsNullableType(objectType))

        ? Nullable.GetUnderlyingType(objectType)

        : objectType;

      return t.IsEnum;

    }

  }

}