src/Lett.Extensions/System.Data/DataTable.cs
using System;
using System.Collections.Generic;
using System.Data;
using System.Linq;
using System.Reflection;
namespace Lett.Extensions
{
/// <summary>
/// DataTable 扩展方法
/// </summary>
public static partial class DataTableExtensions
{
/// <summary>
/// <para><see cref="DataTable" /> 支持的数据类型</para>
/// <remarks>
/// 参考：<a>https://docs.microsoft.com/zh-cn/dotnet/api/system.data.datacolumn.datatype?view=netcore-2.0</a>
/// </remarks>
/// </summary>
public static readonly IReadOnlyList<Type> SupportedDataTypes = new[]
{
typeof(bool),
typeof(byte),
typeof(char),
typeof(DateTime),
typeof(decimal),
typeof(double),
typeof(Guid),
typeof(short),
typeof(int),
typeof(long),
typeof(sbyte),
typeof(float),
typeof(string),
typeof(TimeSpan),
typeof(ushort),
typeof(uint),
typeof(ulong),
typeof(byte[])
};
/// <summary>
/// 是否存在数据行
/// </summary>
/// <param name="this"></param>
/// <returns></returns>
/// <example>
/// <code>
/// <![CDATA[
/// dataTable.HasRows();
/// ]]>
/// </code>
/// </example>
public static bool HasRows(this DataTable @this)
{
return @this.Rows.Count > 0;
}
/// <summary>
/// 获取首行
/// </summary>
/// <param name="this"></param>
/// <returns></returns>
/// <exception cref="ArgumentException">当前DataTable没有行</exception>
/// <example>
/// <code>
/// <![CDATA[
/// dataTable.FirstRow();
/// ]]>
/// </code>
/// </example>
public static DataRow FirstRow(this DataTable @this)
{
if (!@this.HasRows()) throw new ArgumentException("当前DataTable没有行");
return @this.Rows[0];
}
/// <summary>
/// 获取末行
/// </summary>
/// <param name="this"></param>
/// <returns></returns>
/// <exception cref="ArgumentException">当前DataTable没有行</exception>
/// <example>
/// <code>
/// <![CDATA[
/// dataTable.LastRow();
/// ]]>
/// </code>
/// </example>
public static DataRow LastRow(this DataTable @this)
{
if (!@this.HasRows()) throw new ArgumentException("当前DataTable没有行");
return @this.Rows[@this.Rows.Count - 1];
}
/// <summary>
/// 获取DataRow可枚举对象
/// </summary>
/// <param name="this"></param>
/// <returns></returns>
/// <exception cref="ArgumentNullException"><see cref="DataRow" /> 为空</exception>
/// <exception cref="InvalidCastException"></exception>
/// <example>
/// <code>
/// <![CDATA[
/// var rs = dataTable.RowsEnumerable();
/// ]]>
/// </code>
/// </example>
public static IEnumerable<DataRow> RowsEnumerable(this DataTable @this)
{
return @this.Rows.Cast<DataRow>();
}
/// <summary>
/// 获取DataColumn可枚举对象
/// </summary>
/// <param name="this"></param>
/// <returns></returns>
/// <exception cref="ArgumentNullException"><see cref="DataColumn" />为空</exception>
/// <exception cref="InvalidCastException"></exception>
/// <example>
/// <code>
/// <![CDATA[
/// var rs = dataTable.ColumnsEnumerable();
/// ]]>
/// </code>
/// </example>
public static IEnumerable<DataColumn> ColumnsEnumerable(this DataTable @this)
{
return @this.Columns.Cast<DataColumn>();
}
/// <summary>
/// 获取Column的数据类型
/// </summary>
/// <param name="this"></param>
/// <param name="columnName">列名</param>
/// <returns></returns>
/// <exception cref="ArgumentException">DataTable中不包含<paramref name="columnName" /></exception>
/// <example>
/// <code>
/// <![CDATA[
/// var columnType = dt.GetColumnDataType("columnName");
/// ]]>
/// </code>
/// </example>
public static Type GetColumnDataType(this DataTable @this, string columnName)
{
if (!@this.Columns.Contains(columnName)) throw new ArgumentException($"DataTable中不包含Column:{columnName}");
return @this.Columns[columnName].DataType;
}
/// <summary>
/// 获取Column的数据类型
/// </summary>
/// <param name="this"></param>
/// <param name="index">索引</param>
/// <returns></returns>
/// <exception cref="ArgumentOutOfRangeException"><paramref name="index" /> 索引超出了数组范围</exception>
/// <example>
/// <code>
/// <![CDATA[
/// var columnType = dataTable.GetColumnDataType(-1);
/// ]]>
/// </code>
/// </example>
public static Type GetColumnDataType(this DataTable @this, int index)
{
if (index < 0) throw new ArgumentOutOfRangeException(nameof(index), $"{nameof(index)} out of range");
if (@this.Columns.Count - 1 < index) throw new ArgumentOutOfRangeException(nameof(index), $"{nameof(index)} out of range");
return @this.Columns[index].DataType;
}
/// <summary>
/// <para>转换为实体列表</para>
/// <para>使用<see cref="DataRow" />中的值，填充 目标类型 的 <see cref="FieldInfo" /> 与 <see cref="PropertyInfo" /> </para>
/// <para>匹配规则: <see cref="FieldInfo" />.Name 或 <see cref="PropertyInfo" />.Name 与 ColumnName 相同</para>
/// </summary>
/// <param name="this"></param>
/// <typeparam name="T">目标类型</typeparam>
/// <returns>返回 List<<typeparamref name="T" />></returns>
/// <exception cref="ArgumentNullException"><paramref name="this" />.<see cref="DataRow" /> 为空</exception>
/// <exception cref="InvalidCastException"></exception>
/// <exception cref="FieldAccessException"></exception>
/// <exception cref="TargetException"></exception>
/// <exception cref="ArgumentException"></exception>
/// <exception cref="MethodAccessException"></exception>
/// <exception cref="TargetInvocationException"></exception>
/// <exception cref="ArgumentNullException"><paramref name="this" />.<see cref="RowsEnumerable" /> 为空</exception>
/// <example>
/// <code>
/// <![CDATA[
/// var rs = dataTable.ToEntityList<TestClass1>();
/// ]]>
/// </code>
/// </example>
public static List<T> ToEntityList<T>(this DataTable @this) where T : class, new()
{
return @this.RowsEnumerable().Select(s => s.ToEntity<T>()).ToList();
}
/// <summary>
/// 转换为实体列表
/// </summary>
/// <param name="this"></param>
/// <param name="converter">
/// <para>参数 <see cref="DataRow" />: 当前行 </para>
/// <para>参数 <typeparamref name="T" />: 目标新实例</para>
/// </param>
/// <typeparam name="T">目标类型</typeparam>
/// <returns>返回 List<<typeparamref name="T" />></returns>
/// <example>
/// <code>
/// <![CDATA[
/// var rs = dt.ToEntityList<TestClass1>((row, newObj) =>
/// {
/// newObj.PublicField = row.Cell<string>("PublicField");
/// return newObj;
/// });
/// ]]>
/// </code>
/// </example>
public static List<T> ToEntityList<T>(this DataTable @this, Func<DataRow, T, T> converter) where T : class, new()
{
return @this.RowsEnumerable().Select(s => s.ToEntity(converter)).ToList();
}
/// <summary>
/// <para>转换为动态对象集合</para>
/// <para>值为 <see cref="DBNull.Value" /> 转换为 Null </para>
/// </summary>
/// <param name="this"></param>
/// <returns></returns>
/// <example>
/// <code>
/// <![CDATA[
/// var dt = new DataTable();
/// dt.Columns.Add("col1", typeof(string));
/// dt.Columns.Add("col2", typeof(DateTime));
/// dt.Columns.Add("col3", typeof(decimal));
/// dt.Columns.Add("col4", typeof(string));
/// dt.Columns.Add("col5", typeof(string));
/// dt.Rows.Add("strVal", new DateTime(2019, 4, 1), 100.23m, DBNull.Value, null);
/// dt.Rows.Add("strVal2", new DateTime(2019, 4, 2), 122.23m, DBNull.Value, null);
/// var rs = dt.ToDynamicObjects().ToList();
///
/// // rs[0].col1 == "strVal"
/// // rs[0].col2 == new DateTime(2019, 4, 1)
/// // rs[1].col3 == 122.23m
/// // rs[1].col4 is null
/// // rs[1].col5 is null
/// ]]>
/// </code>
/// </example>
public static IEnumerable<dynamic> ToDynamicObjects(this DataTable @this)
{
return @this.RowsEnumerable().Select(row => row.ToDynamicObject());
}
}
}