[英]How to serialize a ViewState objects
我有一些查詢數據庫的函數,並將結果放入gridview。 它還設置一個包含查詢結果的ViewState變量。 當我回發時,我有一個加載函數,從最后的結果(如果有的話)加載gridview。
我遇到的問題是我收到的錯誤基本上表明viewstate對象需要序列化。 從我所擁有的,我不知道如何做到這一點。
錯誤:Sys.WebForms.PageRequestManagerServerErrorException:序列化值'System.Collections.Generic.List
1[<>f__AnonymousType17
2 [System.Int32,System.String]]'的類型為'System.Collections.Generic.List1[[<>f__AnonymousType17
2 [[System.Int32,mscorlib,Version = 4.0.0.0,Culture = neutral,PublicKeyToken = b77a5c561934e089],[System.String,mscorlib,Version = 4.0.0.0,Culture = neutral,PublicKeyToken = b77a5c561934e089]],App_Web_rjb524gi ,Version = 0.0.0.0,Culture = neutral,PublicKeyToken = null]]。'
我的代碼到目前為止:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data;
using System.Runtime.Serialization;
public partial class PlayersManagement : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
if (!Page.IsPostBack)
{
LoadData();
}
}
public void LoadData()
{
if (ViewState["CurrentGridView"] != null || ViewState["CurrentGridView"] == "")
{
GridViewPlayers.DataSource = ViewState["CurrentGridView"];
GridViewPlayers.DataBind();
}
else
{
DBModel.DBEntities context = new DBModel.DBEntities();
var players= (from f in context.Players
where f.isDeleted == false
select new
{
f.PlayerId,
f.PlayerName
}).ToList();
GridViewPlayers.DataSource = players;
GridViewPlayers.DataBind();
}
ViewState["Sort"] = 0;
}
/**
* This method is for advance search functionality
*
*/
protected void btnSearch_Click(object sender, EventArgs e)
{
// If the search textbox is not empty
if (txtSearch.Text.Trim() != "")
{
// Call to Entity Model Framework
DBModel.DBEntities context = new DBModel.DBEntities();
//Querying the Players table
var search = (from s in context.Players
where s.PlayerName.Contains(txtSearch.Text.Trim())
select new
{
s.PlayerId,
s.PlayerName
}).ToList();
if (search.Count != 0)
{
noResults.Visible = false;
GridViewPlayers.DataSource = search;//Connecting query to the datasource Gridview
ViewState["CurrentGridView"] = search; // <---- Error cause here
GridViewPlayers.DataBind(); //Binding Gridview
}
else
{
noResults.Visible = true;
noResults.Text = "This '" + txtSearch.Text + "' Query Returned No Results";
txtSearch.Text = "";
}
}
}
protected void Gridview_Sort(object sender, GridViewSortEventArgs e)
{
//Label2.Text = e.SortExpression + " " + ConvertSortDirectionToSql(e.SortDirection);
DBModel.DBEntities context = new DBModel.DBEntities();
var players = (from b in context.Players
where b.isDeleted == false
select b);
DataTable gridviewTable = players.CopyToDataTable();
gridviewTable.DefaultView.Sort = e.SortExpression + " " + ConvertSortDirectionToSql(e.SortDirection);
GridViewPlayers.DataSource = gridviewTable;
ViewState["CurrentGridView"] = gridviewTable; <--- Also causes error
GridViewPlayers.DataBind();
}
private string ConvertSortDirectionToSql(SortDirection sortDirection)
{
string newSortDirection = String.Empty;
int sort = (ViewState["Sort"] == null) ? 0 : (int)ViewState["Sort"];
switch (sort)
{
case 0:
newSortDirection = "ASC";
ViewState["Sort"] = 1;
break;
case 1:
newSortDirection = "DESC";
ViewState["Sort"] = 0;
break;
}
return newSortDirection;
}
protected void GridViewPlayers_RowEditing(object sender, GridViewEditEventArgs e)
{
GridViewPlayers.EditIndex = e.NewEditIndex;
LoadData();
}
protected void GridViewPlayers_CancelEditRow(object sender, GridViewCancelEditEventArgs e)
{
GridViewPlayers.EditIndex = -1;
LoadData();
}
如果你真的想將它存儲在View State中,那么你可能希望有一個可以標記為[Serializable]
。 看起來匿名類型不是。 所以不要使用:
var search
使用
List<Player> search = Query
和班級。
[Serializable]
public class Player
{
public int PlayerId {get;set;}
public string PlayerName {get;set;}
}
但是,看起來你每次都在查詢數據庫,所以即使你在視圖狀態中存儲也不會獲得任何東西。
問題是,您無法使用ViewState
傳遞匿名對象。 一種解決方案是創建強類型模型,並使用它們代替匿名對象。 創建一個Player
類:
public class Player
{
public Int32 PlayerId { get; set; }
public String PlayerName { get; set; }
}
並像這樣使用它:
var search = (from s in context.Players
where s.PlayerName.Contains(txtSearch.Text.Trim())
select new Player
{
PlayerId = s.PlayerId,
PlayerName = s.PlayerName
}).ToList();
代替:
var search = (from s in context.Players
where s.PlayerName.Contains(txtSearch.Text.Trim())
select new
{
s.PlayerId,
s.PlayerName
}).ToList();
對所有動態結果(更改它們以使用具體類)和綁定resp執行此操作。 序列化 通過ViewState
傳遞應該正常工作。
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