Shrlalgo.RvKits/Sai.Toolkit.Core/Extensions/DataTableExtensions.cs

using System;
using System.Collections;
using System.Collections.Generic;
using System.Data;
using System.Reflection;

namespace Sai.Toolkit.Core.Extensions;

public static class DataTableExtensions
{
	public static string GetValue(this DataTable dt, int row, int column)
	{
		return dt != null ? dt.Rows[row][column].ToString() : string.Empty;
	}

	public static string GetValue(this DataRow dr, int column)
	{
		return dr == null ? throw new ArgumentNullException() : dr[column].ToString();
	}

	public static void SetValue(this DataTable dt, int row, int column, object value)
	{
		dt.Rows[row][column] = value;
	}

	public static void SetValue(this DataRow dr, int column, object value)
	{
		if (dr == null)
		{
			throw new ArgumentNullException();
		}

		dr[column] = value;
	}

	/// <summary>
	///     转实体，属性名必须与列名相同
	/// </summary>
	/// <typeparam name="T"></typeparam>
	/// <param name="table"></param>
	/// <returns></returns>
	public static List<T> ToEntities<T>(this DataTable table)
		where T : new()
	{
		var entities = new List<T>();
		if (table == null)
		{
			return null;
		}

		foreach (DataRow row in table.Rows)
		{
			T entity = new();
			foreach (var item in entity.GetType().GetProperties())
			{
				if (table.Columns.Contains(item.Name))
				{
					if (DBNull.Value != row[item.Name])
					{
						var newType = item.PropertyType;
						//判断type类型是否为泛型，因为nullable是泛型类,
						if (newType.IsGenericType && newType.GetGenericTypeDefinition() == typeof(Nullable<>)) //判断convertsionType是否为nullable泛型类
						{
							//如果type为nullable类，声明一个NullableConverter类，该类提供从Nullable类到基础基元类型的转换
							var nullableConverter = new System.ComponentModel.NullableConverter(newType);
							//将type转换为nullable对的基础基元类型
							newType = nullableConverter.UnderlyingType;
						}

						item.SetValue(entity, Convert.ChangeType(row[item.Name], newType), null);
					}
				}
			}

			entities.Add(entity);
		}

		return entities;
	}

	/// <summary>
	///     将指定的集合转换成DataTable。
	/// </summary>
	/// <param name="list">将指定的集合。</param>
	/// <returns>返回转换后的DataTable。</returns>
	public static DataTable ToDataTable(IList list)
	{
		var table = new DataTable();
		if (list.Count > 0)
		{
			var properties = list[0].GetType().GetProperties();
			foreach (var pi in properties)
			{
				var pt = pi.PropertyType;
				if (pt.IsGenericType && pt.GetGenericTypeDefinition() == typeof(Nullable<>))
				{
					pt = pt.GetGenericArguments()[0];
				}

				table.Columns.Add(new DataColumn(pi.Name, pt));
			}

			for (var i = 0; i < list.Count; i++)
			{
				var tempList = new ArrayList();
				foreach (var pi in properties)
				{
					var obj = pi.GetValue(list[i], null);
					tempList.Add(obj);
				}

				var array = tempList.ToArray();
				table.LoadDataRow(array, true);
			}
		}

		return table;
	}

	public static DataTable ToDataTable<T>(this List<T> list)
	{
		var table = new DataTable();
		//创建列头
		var properties = typeof(T).GetProperties();
		foreach (var pi in properties)
		{
			var pt = pi.PropertyType;
			if (pt.IsGenericType && pt.GetGenericTypeDefinition() == typeof(Nullable<>))
			{
				pt = pt.GetGenericArguments()[0];
			}

			table.Columns.Add(new DataColumn(pi.Name, pt));
		}

		//创建数据行
		if (list.Count > 0)
		{
			for (var i = 0; i < list.Count; i++)
			{
				var tempList = new ArrayList();
				foreach (var pi in properties)
				{
					var obj = pi.GetValue(list[i], null);
					tempList.Add(obj);
				}

				var array = tempList.ToArray();
				table.LoadDataRow(array, true);
			}
		}

		return table;
	}
}