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244 lines
10 KiB
C#
244 lines
10 KiB
C#
//------------------------------------------------------------------------------
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// <copyright file="DataRowExtenstions.cs" company="Microsoft">
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// Copyright (c) Microsoft Corporation. All rights reserved.
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// </copyright>
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// <owner current="true" primary="true">[....]</owner>
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// <owner current="true" primary="false">spather</owner>
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//------------------------------------------------------------------------------
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using System;
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using System.Data.DataSetExtensions;
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namespace System.Data {
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/// <summary>
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/// This static class defines the DataRow extension methods.
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/// </summary>
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public static class DataRowExtensions {
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/// <summary>
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/// This method provides access to the values in each of the columns in a given row.
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/// This method makes casts unnecessary when accessing columns.
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/// Additionally, Field supports nullable types and maps automatically between DBNull and
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/// Nullable when the generic type is nullable.
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/// </summary>
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/// <param name="row">
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/// The input DataRow
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/// </param>
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/// <param name="columnName">
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/// The input column name specificy which row value to retrieve.
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/// </param>
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/// <returns>
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/// The DataRow value for the column specified.
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/// </returns>
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public static T Field<T>(this DataRow row, string columnName) {
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DataSetUtil.CheckArgumentNull(row, "row");
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return UnboxT<T>.Unbox(row[columnName]);
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}
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/// <summary>
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/// This method provides access to the values in each of the columns in a given row.
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/// This method makes casts unnecessary when accessing columns.
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/// Additionally, Field supports nullable types and maps automatically between DBNull and
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/// Nullable when the generic type is nullable.
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/// </summary>
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/// <param name="row">
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/// The input DataRow
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/// </param>
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/// <param name="column">
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/// The input DataColumn specificy which row value to retrieve.
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/// </param>
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/// <returns>
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/// The DataRow value for the column specified.
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/// </returns>
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public static T Field<T>(this DataRow row, DataColumn column) {
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DataSetUtil.CheckArgumentNull(row, "row");
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return UnboxT<T>.Unbox(row[column]);
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}
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/// <summary>
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/// This method provides access to the values in each of the columns in a given row.
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/// This method makes casts unnecessary when accessing columns.
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/// Additionally, Field supports nullable types and maps automatically between DBNull and
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/// Nullable when the generic type is nullable.
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/// </summary>
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/// <param name="row">
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/// The input DataRow
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/// </param>
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/// <param name="columnIndex">
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/// The input ordinal specificy which row value to retrieve.
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/// </param>
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/// <returns>
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/// The DataRow value for the column specified.
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/// </returns>
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public static T Field<T>(this DataRow row, int columnIndex) {
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DataSetUtil.CheckArgumentNull(row, "row");
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return UnboxT<T>.Unbox(row[columnIndex]);
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}
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/// <summary>
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/// This method provides access to the values in each of the columns in a given row.
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/// This method makes casts unnecessary when accessing columns.
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/// Additionally, Field supports nullable types and maps automatically between DBNull and
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/// Nullable when the generic type is nullable.
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/// </summary>
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/// <param name="row">
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/// The input DataRow
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/// </param>
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/// <param name="columnIndex">
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/// The input ordinal specificy which row value to retrieve.
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/// </param>
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/// <param name="version">
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/// The DataRow version for which row value to retrieve.
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/// </param>
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/// <returns>
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/// The DataRow value for the column specified.
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/// </returns>
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public static T Field<T>(this DataRow row, int columnIndex, DataRowVersion version) {
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DataSetUtil.CheckArgumentNull(row, "row");
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return UnboxT<T>.Unbox(row[columnIndex, version]);
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}
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/// <summary>
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/// This method provides access to the values in each of the columns in a given row.
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/// This method makes casts unnecessary when accessing columns.
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/// Additionally, Field supports nullable types and maps automatically between DBNull and
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/// Nullable when the generic type is nullable.
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/// </summary>
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/// <param name="row">
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/// The input DataRow
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/// </param>
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/// <param name="columnName">
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/// The input column name specificy which row value to retrieve.
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/// </param>
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/// <param name="version">
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/// The DataRow version for which row value to retrieve.
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/// </param>
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/// <returns>
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/// The DataRow value for the column specified.
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/// </returns>
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public static T Field<T>(this DataRow row, string columnName, DataRowVersion version) {
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DataSetUtil.CheckArgumentNull(row, "row");
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return UnboxT<T>.Unbox(row[columnName, version]);
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}
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/// <summary>
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/// This method provides access to the values in each of the columns in a given row.
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/// This method makes casts unnecessary when accessing columns.
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/// Additionally, Field supports nullable types and maps automatically between DBNull and
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/// Nullable when the generic type is nullable.
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/// </summary>
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/// <param name="row">
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/// The input DataRow
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/// </param>
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/// <param name="column">
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/// The input DataColumn specificy which row value to retrieve.
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/// </param>
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/// <param name="version">
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/// The DataRow version for which row value to retrieve.
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/// </param>
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/// <returns>
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/// The DataRow value for the column specified.
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/// </returns>
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public static T Field<T>(this DataRow row, DataColumn column, DataRowVersion version) {
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DataSetUtil.CheckArgumentNull(row, "row");
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return UnboxT<T>.Unbox(row[column, version]);
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}
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/// <summary>
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/// This method sets a new value for the specified column for the DataRow it’s called on.
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/// </summary>
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/// <param name="row">
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/// The input DataRow.
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/// </param>
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/// <param name="columnIndex">
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/// The input ordinal specifying which row value to set.
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/// </param>
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/// <param name="value">
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/// The new row value for the specified column.
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/// </param>
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public static void SetField<T>(this DataRow row, int columnIndex, T value) {
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DataSetUtil.CheckArgumentNull(row, "row");
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row[columnIndex] = (object)value ?? DBNull.Value;
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}
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/// <summary>
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/// This method sets a new value for the specified column for the DataRow it’s called on.
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/// </summary>
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/// <param name="row">
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/// The input DataRow.
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/// </param>
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/// <param name="columnName">
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/// The input column name specificy which row value to retrieve.
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/// </param>
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/// <param name="value">
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/// The new row value for the specified column.
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/// </param>
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public static void SetField<T>(this DataRow row, string columnName, T value) {
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DataSetUtil.CheckArgumentNull(row, "row");
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row[columnName] = (object)value ?? DBNull.Value;
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}
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/// <summary>
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/// This method sets a new value for the specified column for the DataRow it’s called on.
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/// </summary>
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/// <param name="row">
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/// The input DataRow.
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/// </param>
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/// <param name="column">
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/// The input DataColumn specificy which row value to retrieve.
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/// </param>
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/// <param name="value">
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/// The new row value for the specified column.
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/// </param>
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public static void SetField<T>(this DataRow row, DataColumn column, T value) {
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DataSetUtil.CheckArgumentNull(row, "row");
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row[column] = (object)value ?? DBNull.Value;
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}
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private static class UnboxT<T>
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{
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internal static readonly Converter<object, T> Unbox = Create(typeof(T));
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private static Converter<object, T> Create(Type type)
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{
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if (type.IsValueType)
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{
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if (type.IsGenericType && !type.IsGenericTypeDefinition && (typeof(Nullable<>) == type.GetGenericTypeDefinition()))
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{
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return (Converter<object, T>)Delegate.CreateDelegate(
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typeof(Converter<object, T>),
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typeof(UnboxT<T>)
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.GetMethod("NullableField", System.Reflection.BindingFlags.Static | System.Reflection.BindingFlags.NonPublic)
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.MakeGenericMethod(type.GetGenericArguments()[0]));
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}
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return ValueField;
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}
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return ReferenceField;
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}
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private static T ReferenceField(object value)
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{
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return ((DBNull.Value == value) ? default(T) : (T)value);
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}
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private static T ValueField(object value)
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{
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if (DBNull.Value == value)
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{
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throw DataSetUtil.InvalidCast(Strings.DataSetLinq_NonNullableCast(typeof(T).ToString()));
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}
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return (T)value;
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}
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private static Nullable<TElem> NullableField<TElem>(object value) where TElem : struct
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{
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if (DBNull.Value == value)
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{
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return default(Nullable<TElem>);
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}
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return new Nullable<TElem>((TElem)value);
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}
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}
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}
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}
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