Shrlalgo.RvKits/ShrlAlgoToolkit.Core/Extensions/DataTableExtensions.cs

using System.Collections;
using System.Data;

namespace ShrlAlgo.Toolkit.Core.Extensions;

public static class DataTableExtensions
{
    /// <summary>
    /// 获取数据
    /// </summary>
    /// <param name="dt"></param>
    /// <param name="row"></param>
    /// <param name="column"></param>
    /// <returns></returns>
	public static string GetValue(this DataTable dt, int row, int column)
    {
        return dt != null ? dt.Rows[row][column].ToString() : string.Empty;
    }
    /// <summary>
    /// 获取值
    /// </summary>
    /// <param name="dr"></param>
    /// <param name="column"></param>
    /// <returns></returns>
    /// <exception cref="ArgumentNullException"></exception>
	public static string GetValue(this DataRow dr, int column)
    {
        return dr == null ? throw new ArgumentNullException(nameof(dr)) : dr[column].ToString();
    }
    /// <summary>
    /// 设置值
    /// </summary>
    /// <param name="dt"></param>
    /// <param name="row"></param>
    /// <param name="column"></param>
    /// <param name="value"></param>
	public static void SetValue(this DataTable dt, int row, int column, object value)
    {
        dt.Rows[row][column] = value;
    }
    /// <summary>
    /// 设置值
    /// </summary>
    /// <param name="dr"></param>
    /// <param name="column"></param>
    /// <param name="value"></param>
    /// <exception cref="ArgumentNullException"></exception>
	public static void SetValue(this DataRow dr, int column, object value)
    {
        if (dr == null)
        {
            throw new ArgumentNullException(nameof(dr));
        }

        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(this IList list)
    {
        var table = new DataTable();

        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;
    }
}