C's method of converting DataTable to list
- 2020-12-13 19:04:42
- OfStack
This article gives an example of how C# translates DataTable to list and data paging. Share to everybody for everybody reference. The details are as follows:
/// <summary>
/// Hotel Review list - paging
/// </summary>
/// <param name="userId"></param>
/// <param name="pageIndex"> The current page </param>
/// <param name="pageCount"> Total number of pages </param>
/// <returns></returns>
public static List<CommentInfo> GetHotelCommentList(int userId, int pageIndex, out int pageCount)
{
var list = new List<CommentInfo>();
pageCount = 0;
try
{
// Query the hotel ID, The name , The picture , The user ID, User comments
string sql = string.Format( @"select hotels.hid,hotels.hotelName,hotels.images,hotelorder.UserID,user_HotelComment.comment from hotels with(nolock) join hotelorder with(nolock) join user_HotelComment
telorder.UserID=user_HotelComment.userID on hotels.hid=hotelorder.HotelID where hotelorder.UserID={0}", userId);
DataTable dt = SQLHelper.Get_DataTable(sql, SQLHelper.GetCon(), null);
if (dt != null && dt.Rows.Count > 0)
{
list = (from p in dt.AsEnumerable() // this list Find out all the user reviews
select new CommentInfo
{
Id = p.Field<int>("hid"), //p.Filed<int>("Id") It's really about getting DataRow In the ID The column. That is: row["ID"]
HotelImages = p.Field<string>("images"),
HotelName = p.Field<string>("hotelName"),
Comment = p.Field<string>("comment")
}).ToList(); // Convert this set to list
int pageSize = 10; // Each page shows 10 The data
// Get total pages
pageCount = list.Count % pageSize == 0 ? ((list.Count - pageSize >= 0 ? (list.Count / pageSize) : (list.Count == 0 ? 0 : 1))) : list.Count / pageSize + 1;
// this list Is taken to 10 The data
//Skip Skips the specified number of elements in the sequence, and returns the remaining elements.
//Take The beginning of a sequence returns a specified number of consecutive elements.
list = list.Skip(pageSize * (pageIndex - 1)).Take(pageSize).ToList(); // Assume the current page is at number 1 3 Page. So I'm going to skip over here 10*(3-1) The skip 20 The data, Take(pageSize) mean : take 10 The data , Now that I've skipped the previous one 20 So that's the number. So here's the number 21 So let's go. Take 10 The cough up
}
}
catch (Exception ex)
{
// write log here
}
return list;
}
Convert 1 DataTable to 1 List
First define a class that accepts the DataTable field column. The field of the class is sent to column field 1 of DataTable
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
namespace WebApplication1
{
/// <summary>
/// The user information
/// </summary>
public class User
{
public int Id { get; set; }
public string UserName { get; set; }
public int Age { get; set; }
public int Gender { get; set; }
}
}
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using JSON.Controllers;
using System.Data;
namespace WebApplication1
{
public class Class1
{
/// <summary>
/// will DataTable Converted to 1 a list
/// </summary>
/// <returns> return 1 a List<User> object </returns>
public List<User> TableToList()
{
string sql = "select * from T_User"; //T_User There are all of them id,UserName,Age,Gender4 column
DataTable dt= SqlHelper.ExecuteDataTable(sql,null);
var list = new List<User>(); // create 1 a List<User> An instance of the
if (dt != null && dt.Rows.Count > 0)
{
//AsEnumerable() Returns the 1 a IEnumerable<T> Object whose generic parameters T for System.Data.DataRow .
list = (from p in dt.AsEnumerable()
select new User //new1 a User object
{
Id = p.Field<int>("id"),//p.Filed<int>("id") It's really about getting DataRow In the ID The column. That is: row["ID"] And then assign it to User Of the class Id Field.
UserName = p.Field<string>("UserName"),
Age = p.Field<int>("Age"),
Gender = p.Field<int>("Gender")
}).ToList(); // Will this User Class object to list
}
int dataCount = list.Count; // Total number of data bars.
int pageSize=10;// How many pieces of data are displayed per page.
int pageCount; // The total number of pages.
int currentPage=3;// The current page. -- This assumes that the current page is page 1 3 Page.
pageCount = dataCount % pageSize == 0 ? (dataCount < pageSize ? (dataCount==0?0:1): (dataCount / pageSize)) : (dataCount / pageSize + 1);
// this list Is taken to 10 The data
//Skip Skips the specified number of elements in the sequence, and returns the remaining elements.
//Take The beginning of a sequence returns a specified number of consecutive elements.
list = list.Skip(pageSize * (currentPage - 1)).Take(pageSize).ToList(); // Assume the current page is at number 1 3 Page. So I'm going to skip over here 10*(3-1) The skip 20 The data, Take(pageSize) mean : take 10 The data , Now that I've skipped the previous one 20 So that's the number. So here's the number 21 So let's go. Take 10 The cough up
return list;
}
}
}Hopefully this article has helped you with your C# programming.