如何序列化 ViewState 对象

Question

我有一些函数可以查询数据库并将结果放入网格视图中。它还设置了一个包含查询结果的 ViewState 变量。当我回发时，我有一个加载函数，可以从最后的结果中加载 gridview（如果有的话）。

我遇到的问题是我收到一个错误，基本上说 viewstate 对象需要被序列化。从我所拥有的情况来看，我不确定该怎么做。

错误：Sys.WebForms.PageRequestManagerServerErrorException：错误 序列化值 'System.Collections.Generic.List1[<>f__AnonymousType172[System.Int32,System.String]]' 类型 'System.Collections.Generic.List1[[<>f__AnonymousType172[[System.Int32, mscorlib，版本=4.0.0.0，文化=中性， PublicKeyToken=b77a5c561934e089],[System.String, mscorlib, 版本=4.0.0.0，文化=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：

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();
}

Answer 1

如果您真的想将它存储在 View State 中，那么您可能希望有一个可以标记为 [Serializable] 的类型。看起来匿名类型不是。所以不要使用：

var search

使用

 List<Player> search =  Query  

还有班级。

[Serializable]
public class Player
{
    public int PlayerId {get;set;}
    public string PlayerName {get;set;}
}

但是，看起来您每次都在查询数据库，所以即使您确实存储在视图状态中，您也不会获得任何东西。

Answer 2

问题是，您不能使用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Player 类：

public class Player
{
    public Int32 PlayerId { get; set; }
    public String PlayerName { get; set; }
}

并像这样使用它：

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

    }).ToList();

代替：

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resp。序列化分别通过ViewState 应该可以正常工作。