C# 如何序列化ViewState对象

C# 如何序列化ViewState对象,c#,linq,entity-framework,gridview,viewstate,C#,Linq,Entity Framework,Gridview,Viewstate,我有一些查询数据库并将结果放入gridview的函数。它还设置一个ViewState变量,该变量包含查询结果。当我回发时,我有一个加载函数,从最后的结果加载gridview(如果有的话) 我遇到的问题是,我得到一个错误,基本上是说viewstate对象需要序列化。从我所拥有的,我不知道如何做到这一点 错误:Sys.WebForms.PageRequestManagerServerErrorException:错误 序列化值 'System.Collections.Generic.List1[f_

我有一些查询数据库并将结果放入gridview的函数。它还设置一个ViewState变量,该变量包含查询结果。当我回发时,我有一个加载函数,从最后的结果加载gridview(如果有的话)

我遇到的问题是,我得到一个错误,基本上是说viewstate对象需要序列化。从我所拥有的,我不知道如何做到这一点

错误:Sys.WebForms.PageRequestManagerServerErrorException:错误 序列化值 'System.Collections.Generic.List1[f_uAnonymousType172[System.Int32,System.String]' 类型 'System.Collections.Generic.List1[[f_uuAnonymousType172[[System.Int32, mscorlib,版本=4.0.0.0,区域性=中性, PublicKeyToken=b77a5c561934e089],[System.String,mscorlib, 版本=4.0.0.0,区域性=中性,PublicKeyToken=b77a5c561934e089], App_Web_rjb524gi,版本=0.0.0.0,文化=中性, PublicKeyToken=null].'

到目前为止,我的代码是:

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();
}

如果您真的想将其存储在视图状态,那么您可能需要一个可以标记为[Serializable]的类型。看起来匿名类型不是。因此,与其使用:

var search
使用


但是,看起来每次都在查询数据库,因此即使存储在viewstate中,也不会获得任何结果

问题是,无法使用ViewState传递匿名对象。一种解决方案是创建强类型模型,并使用它们代替匿名对象。创建一个玩家类:

然后像这样使用它:

var search = (from s in context.Players
    where s.PlayerName.Contains(txtSearch.Text.Trim())
    select new Player
    {
        PlayerId = s.PlayerId,
        PlayerName = s.PlayerName

    }).ToList();
而不是:

var search = (from s in context.Players
    where s.PlayerName.Contains(txtSearch.Text.Trim())
    select new
    {
        s.PlayerId,
        s.PlayerName

    }).ToList();

对所有动态结果执行此操作将它们更改为使用具体类和绑定响应。序列化响应。通过ViewState传递应该可以正常工作。

GridViewPlayer.DataSource=ViewState[CurrentGridView];无法正确反序列化该类。一种选择是添加一个类Player{public int PlayerId;public string PlayerName;}并强制转换结果,例如GridViewPlayers.DataSource=List ViewState[CurrentGridView];会话似乎可以工作,但我不希望会话对象在应用程序周围浮动,而是希望在页面更改时终止它。这会更好吗?所以我认为使用EF实体框架的目的是让开发人员不必创建模型类。如果您的实体已经创建了Player类,那么请尝试将ViewState['something']强制转换为Player[]和/或ListYes,这是EF为帮助开发人员而完成的任务之一,但是您没有使用EF创建的类。相反,您正在创建一个。如果您已经有一个从EF创建的玩家类,那么使用它而不是选择new{。。。。
public class Player
{
    public Int32 PlayerId { get; set; }
    public String PlayerName { get; set; }
}
var search = (from s in context.Players
    where s.PlayerName.Contains(txtSearch.Text.Trim())
    select new Player
    {
        PlayerId = s.PlayerId,
        PlayerName = s.PlayerName

    }).ToList();
var search = (from s in context.Players
    where s.PlayerName.Contains(txtSearch.Text.Trim())
    select new
    {
        s.PlayerId,
        s.PlayerName

    }).ToList();