/// <summary>
/// Tries to write out a possible geography value into json
/// </summary>
/// <param name="geographyValue">The geography value to serialize into Json</param>
/// <param name="writer">The Json writer being used to write out a Json payload</param>
/// <returns>true, if the value is a geography object that is supported, false otherwise.</returns>
private static bool TryWriteGeography(object geographyValue, JsonWriter writer)
{
Assert.IsNotNull(geographyValue, "Can't write a null geography.");
Assert.IsNotNull(writer, "JsonWriter is null.");
Type type = geographyValue.GetType();
if (typeof(GeographyPoint).IsAssignableFrom(type))
{
GeographyPoint point = (GeographyPoint)geographyValue;
WriteGeographyPoint(point, writer);
return true;
}
else if (typeof(GeographyLineString).IsAssignableFrom(type))
{
GeographyLineString lineString = (GeographyLineString)geographyValue;
WriteGeographyLineString(lineString, writer);
return true;
}
return false;
}
/// <summary>
/// Writes out a GeographyLineString value in geojson format.
/// {
/// "__metadata": {"type": "Edm.GeographyLineString"},
/// { "type" :"LineString",
/// "coordinates": { [-122.1202778,47.6741667] } ,
/// "crs":{"type":"name","properties":{"name":"EPSG:4326"}}
/// }
/// }
/// </summary>
/// <param name="geographyLineStringValue">The geography value to serialize into Json</param>
/// <param name="writer">The Json writer being used to write out a Json payload</param>
private static void WriteGeographyLineString(GeographyLineString lineString, JsonWriter writer)
{
// {
writer.StartObjectScope();
// "__metadata":
writer.WriteName(JsonMetadataString);
// {
writer.StartObjectScope();
// "type"
writer.WriteName(JsonTypeString);
// "Edm.GeographyLineString"
writer.WriteValue(Gml_Edm_GeographyLineStringName);
// }
writer.EndScope();
// "type":"LineString",
writer.WriteName(JsonTypeString);
writer.WriteValue(GmlLineString);
// "coordinates":
writer.WriteName(JsonCoOrdinatesString);
// [
writer.StartArrayScope();
foreach (var point in lineString.Points)
{
WritePointCoordinates(writer, point);
}
// ]
writer.EndScope();
// "crs": {"type": "name", "properties": {"name": "EPSG:4326"}}
WriteCrsElement(writer, lineString.CoordinateSystem.EpsgId);
// }
writer.EndScope();
}
/// <summary>
/// Attempts to convert the specified primitive value to a serializable string.
/// </summary>
/// <param name="value">Non-null value to convert.</param>
private static void WritePrimitiveJsonValue(JsonWriter writer, object value)
{
Debug.Assert(value != null, "value != null");
Type valueType = value.GetType();
if (typeof(String) == valueType)
{
writer.WriteValue((string)value);
}
else if (typeof(System.Xml.Linq.XElement) == valueType)
{
writer.WriteValue(((System.Xml.Linq.XElement)value).ToString(System.Xml.Linq.SaveOptions.None));
}
else if (typeof(SByte) == valueType)
{
writer.WriteValue((SByte)value);
}
else if (typeof(Boolean) == value.GetType())
{
writer.WriteValue((bool)value);
}
else if (typeof(Byte) == value.GetType())
{
writer.WriteValue((byte)value);
}
else if (typeof(DateTime) == value.GetType())
{
writer.WriteValue((DateTime)value);
}
else if (typeof(Decimal) == value.GetType())
{
writer.WriteValue((Decimal)value);
}
else if (typeof(Double) == value.GetType())
{
writer.WriteValue((Double)value);
}
else if (typeof(Guid) == value.GetType())
{
writer.WriteValue((Guid)value);
}
else if (typeof(Int16) == value.GetType())
{
writer.WriteValue((Int16)value);
}
else if (typeof(Int32) == value.GetType())
{
writer.WriteValue((Int32)value);
}
else if (typeof(Int64) == value.GetType())
{
writer.WriteValue((Int64)value);
}
else if (typeof(Single) == value.GetType())
{
writer.WriteValue((Single)value);
}
else if (typeof(byte[]) == value.GetType())
{
byte[] byteArray = (byte[])value;
string result = Convert.ToBase64String(byteArray, Base64FormattingOptions.None);
writer.WriteValue(result);
}
else if (!TryWriteGeography(value, writer))
{
Debug.Assert(typeof(System.Data.Linq.Binary) == value.GetType(), "typeof(Binary) == value.GetType() (" + value.GetType() + ")");
WritePrimitiveJsonValue(writer, ((System.Data.Linq.Binary)value).ToArray());
}
}
/// <summary>
/// Creates a Json serializer.
/// </summary>
/// <param name="output">Output stream.</param>
/// <param name="encoding">Stream encoding.</param>
public DSPResourceJsonSerializer(Stream output, Encoding encoding)
{
encoding = encoding ?? Encoding.UTF8;
writer = new JsonWriter(new StreamWriter(output, encoding));
}
/// <summary>
/// Writes out a geography point's Co-ordinates in JSON
/// </summary>
/// <param name="writer">The Json Writer being used to write out the results.</param>
/// <param name="point">The Point to serialize into JSON</param>
private static void WritePointCoordinates(JsonWriter writer, GeographyPoint point)
{
writer.StartArrayScope();
writer.WriteValue(point.Longitude);
writer.WriteValue(point.Latitude);
writer.EndScope();
}
/// <summary>
/// Writes out the Co-ordinate reference system element in JSON
/// http://en.wikipedia.org/wiki/Coordinate_reference_system
/// </summary>
/// <param name="writer">The Json Writer being used to write out the results.</param>
/// <param name="epsgId">the EpsgId value to serialize</param>
private static void WriteCrsElement(JsonWriter writer, int? epsgId)
{
// "crs"
writer.WriteName(JsonCrsString);
// {
writer.StartObjectScope();
// "type"
writer.WriteName(JsonTypeString);
// :"name"
writer.WriteValue(JsonNameString);
// "properties"
writer.WriteName(PropertiesElementName);
// : {
writer.StartObjectScope();
// "name":
writer.WriteName(JsonNameString);
string epsgidValue = epsgId.HasValue ? epsgId.Value.ToString() : "0";
// "EPSG:<EpsgIdValue>"
writer.WriteValue(String.Format(JsonEPSGValueStringFormat, epsgidValue));
// }
writer.EndScope();
// }
writer.EndScope();
}
/// <summary>
/// Writes out a GeographyPoint value in geojson format.
/// {
/// "__metadata":{"type":"Edm.GeographyPoint"},
/// "type":"Point",
/// "coordinates":[Lattitude,Longitude],
/// "crs":{"type":"name","properties":{"name":"EPSG:EPSGValue"}}
/// }
/// </summary>
/// <param name="geographyLineStringValue">The geography value to serialize into Json</param>
/// <param name="writer">The Json writer being used to write out a Json payload</param>
private static void WriteGeographyPoint(GeographyPoint point, JsonWriter writer)
{
// see http://geojson.org/geojson-spec.html#id9
// {
writer.StartObjectScope();
// "__metadata":
writer.WriteName(JsonMetadataString);
// {
writer.StartObjectScope();
// "type"
writer.WriteName(JsonTypeString);
// "Edm.GeographyPoint"
writer.WriteValue(Gml_Edm_GeographyPointName);
// }
writer.EndScope();
// "type":"Point",
writer.WriteName(JsonTypeString);
writer.WriteValue(GmlPoint);
// "coordinates":[-122.1202778,47.6741667],
writer.WriteName(JsonCoOrdinatesString);
WritePointCoordinates(writer, point);
// "crs": {"type": "name", "properties": {"name": "EPSG:4326"}}
WriteCrsElement(writer, point.CoordinateSystem.EpsgId);
// }
writer.EndScope();
}
