[转载]C#.NET DataTable扩展 ToList/Get/OrderBy/Where/ToPage

最新推荐文章于 2024-08-07 15:07:06 发布

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最新推荐文章于 2024-08-07 15:07:06 发布

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本文介绍了一系列针对DataTable的扩展方法，包括转换为列表、排序、筛选等实用功能，旨在提高.NET应用程序中数据处理的效率。

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http://www.cnblogs.com/livexy/archive/2010/07/06/1772213.html

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Reflection;
using System.Data;
using System.Data.Common;
using System.Web.Script.Serialization;
using System.IO;
using System.Security.Cryptography;

namespace Pub.Class {
    public static class DataTableExtensions {

        public static List<TResult> ToList<TResult>(this DataTable dt) where TResult : class,new() {
            List<TResult> list= new List<TResult>();
            if (dt == null) return list;
            int len = dt.Rows.Count;

            for (int i = 0; i < len; i++) {
                TResult info = new TResult();
                foreach (DataColumn dc in dt.Rows[i].Table.Columns) {
                    if (dt.Rows[i][dc.ColumnName] == null || string.IsNullOrEmpty(dt.Rows[i][dc.ColumnName].ToString())) continue;
                    System.Reflection.PropertyInfo pi = info.GetType().GetProperty(dc.ColumnName);
                    pi.SetValue(info, dt.Rows[i][dc.ColumnName], null);
                }
                list.Add(info);
            }
            dt.Dispose(); dt = null;
            return list;
        }
        public static DataTable OrderBy(this DataTable dt, string orderBy) {
            dt.DefaultView.Sort = orderBy;
            return dt.DefaultView.ToTable();
        }
        public static DataTable Where(this DataTable dt, string where) {
            DataTable resultDt = dt.Clone();
            DataRow[] resultRows = dt.Select(where);
            foreach (DataRow dr in resultRows) resultDt.Rows.Add(dr.ItemArray);
            return resultDt;
        }
        public static List<TResult> OrderBy<TResult>(this DataTable dt, string orderBy) where TResult : class,new() {
            return dt.OrderBy(orderBy).ToList<TResult>();
        }
        public static List<TResult> Where<TResult>(this DataTable dt, string where) where TResult : class,new() {
            return dt.Where(where).ToList<TResult>();
        }
        public static List<TResult> ToPage<TResult>(this DataTable dt, int pageIndex,int pageSize,out int totalRecords) where TResult : class,new() {
            totalRecords = dt.Rows.Count;
            int startRow = (pageIndex - 1) * pageSize;
            int endRow = startRow + pageSize;
            if (startRow > totalRecords || startRow < 0) { startRow = 0; endRow = pageSize; }
            if (endRow > totalRecords + pageSize) { startRow = totalRecords - pageSize; endRow = totalRecords; }

            DataTable dt2 = dt.Clone();
            for (int i = startRow; i < endRow; i++) { if (i >= totalRecords) break; dt2.Rows.Add(dt.Rows[i].ItemArray); }

            return dt2.ToList<TResult>();
        }

        public static T Get<T>(this DataRow row, string field) { return row.Get<T>(field, default(T)); }
        public static T Get<T>(this DataRow row, string field, T defaultValue) {
            var value = row[field];
            if(value == DBNull.Value) return defaultValue;
            return value.ConvertTo<T>(defaultValue);
        }
        public static T Get<T>(this DataRowView row, string field) { return row.Get<T>(field, default(T)); }
        public static T Get<T>(this DataRowView row, string field, T defaultValue) {
            var value = row[field];
            if(value == DBNull.Value) return defaultValue;
            return value.ConvertTo<T>(defaultValue);
        }

    }
}