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//------------------------------------------------------------------------------
// <copyright file="SqlSpatialDataReader.cs" company="Microsoft">
// Copyright (c) Microsoft Corporation. All rights reserved.
// </copyright>
//
// @owner willa
// @backupOwner Microsoft
//------------------------------------------------------------------------------
using System.Data.Common.Utils;
using System.Data.Entity;
using System.Data.Spatial;
using System.Data.SqlTypes;
using System.Diagnostics;
using System.IO;
using System.Linq.Expressions;
using System.Reflection;
namespace System.Data.SqlClient
{
/// <summary>
/// SqlClient specific implementation of <see cref="DbSpatialDataReader"/>
/// </summary>
internal sealed partial class SqlSpatialDataReader : DbSpatialDataReader
{
private readonly SqlDataReader reader;
private const string geometrySqlType = "sys.geometry";
private const string geographySqlType = "sys.geography";
internal SqlSpatialDataReader(SqlDataReader underlyingReader)
{
this.reader = underlyingReader;
}
public override DbGeography GetGeography(int ordinal)
{
EnsureGeographyColumn(ordinal);
SqlBytes geogBytes = this.reader.GetSqlBytes(ordinal);
object providerValue = sqlGeographyFromBinaryReader.Value(new BinaryReader(geogBytes.Stream));
return SqlSpatialServices.Instance.GeographyFromProviderValue(providerValue);
}
public override DbGeometry GetGeometry(int ordinal)
{
EnsureGeometryColumn(ordinal);
SqlBytes geomBytes = this.reader.GetSqlBytes(ordinal);
object providerValue = sqlGeometryFromBinaryReader.Value(new BinaryReader(geomBytes.Stream));
return SqlSpatialServices.Instance.GeometryFromProviderValue(providerValue);
}
private static readonly Singleton<Func<BinaryReader, object>> sqlGeographyFromBinaryReader = new Singleton<Func<BinaryReader, object>>(() => CreateBinaryReadDelegate(SqlProviderServices.GetSqlTypesAssembly().SqlGeographyType));
private static readonly Singleton<Func<BinaryReader, object>> sqlGeometryFromBinaryReader = new Singleton<Func<BinaryReader, object>>(() => CreateBinaryReadDelegate(SqlProviderServices.GetSqlTypesAssembly().SqlGeometryType));
// test to ensure that the SQL column has the expected SQL type. Don't use the CLR type to avoid having to worry about differences in
// type versions between the client and the database.
private void EnsureGeographyColumn(int ordinal)
{
string fieldTypeName = this.reader.GetDataTypeName(ordinal);
if (!fieldTypeName.EndsWith(geographySqlType, StringComparison.Ordinal)) // Use EndsWith so that we just see the schema and type name, not the database name.
{
throw new InvalidDataException(Strings.SqlProvider_InvalidGeographyColumn(fieldTypeName));
}
}
private void EnsureGeometryColumn(int ordinal)
{
string fieldTypeName = this.reader.GetDataTypeName(ordinal);
if (!fieldTypeName.EndsWith(geometrySqlType, StringComparison.Ordinal)) // Use EndsWith so that we just see the schema and type name, not the database name.
{
throw new InvalidDataException(Strings.SqlProvider_InvalidGeometryColumn(fieldTypeName));
}
}
/// <summary>
/// Builds and compiles the Expression equivalent of the following:
///
/// (BinaryReader r) => { var result = new SpatialType(); result.Read(r); return r; }
///
/// The construct/read pattern is preferred over casting the result of calling GetValue on the DataReader,
/// because constructing the value directly allows client code to specify the type, rather than SqlClient using
/// the server-specified assembly qualified type name from TDS to try to locate the correct type on the client.
/// </summary>
/// <param name="spatialType"></param>
/// <returns></returns>
private static Func<BinaryReader, object> CreateBinaryReadDelegate(Type spatialType)
{
Debug.Assert(spatialType != null, "Ensure spatialType is non-null before calling CreateBinaryReadDelegate");
var readerParam = Expression.Parameter(typeof(BinaryReader));
var binarySerializable = Expression.Variable(spatialType);
var readMethod = spatialType.GetMethod("Read", BindingFlags.Public | BindingFlags.Instance, null, new[] { typeof(System.IO.BinaryReader) }, null);
var ex = Expression.Lambda<Func<BinaryReader, object>>(
Expression.Block(
new[] { binarySerializable },
Expression.Assign(binarySerializable, Expression.New(spatialType)),
Expression.Call(binarySerializable, readMethod, readerParam),
binarySerializable
),
readerParam
);
Func<BinaryReader, object> result = ex.Compile();
return result;
}
}
}
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