using System;

using System.Collections.Generic;

using System.ComponentModel.DataAnnotations.Schema;

using System.Data;

using System.Reflection;

using System.Text;

namespace TJCFinanceWriteOff.BizLogic.Common

{

    public class DataTableUtil

    {

        /// <summary>

        /// 将DataRow转换为实体对象

        /// </summary>

        /// <typeparam name="T"></typeparam>

        /// <param name="dr"></param>

        /// <returns></returns>

        public static T ConvertToEntity<T>(DataRow dr) where T : new()

        {

            T entity = new T();

            Type info = typeof(T);

            var properties = info.GetProperties();

            string columnName = string.Empty;

            object propName = DBNull.Value;

            foreach (var prop in properties)

            {

                //1.判断该属性是否可写

                if (!prop.CanWrite)

                {

                    continue;

                }

                //2.查看实体类是否有数据库相关特性，没有则以属性名作为名称

                var attributes = prop.GetCustomAttribute<ColumnAttribute>();

                if (attributes is null)

                {

                    columnName = prop.Name;

                }

                else

                {

                    columnName = attributes.Name ?? prop.Name;

                }

                if (!dr.Table.Columns.Contains(columnName))

                {

                    continue;

                }

                propName = dr[columnName];

                if (propName != DBNull.Value)

                {

                    //根据ColumnName，将dr中的相对字段赋值给Entity属性

                    prop.SetValue(entity, Convert.ChangeType(propName, prop.PropertyType), null);

                }

            }

            return entity;

        }

        /// <summary>

        ///

        /// </summary>

        /// <typeparam name="T"></typeparam>

        /// <param name="dt"></param>

        /// <returns></returns>

        public static List<T> ToEntityList<T>(DataTable dt) where T : new()

        {

            List<T> list = new List<T>(dt.Rows.Count);

            foreach (DataRow dr in dt.Rows)

            {

                list.Add(ConvertToEntity<T>(dr));

            }

            return list;

        }

    }

}