ADO.net实体回发Gridview数据源

Question

我正在尝试将ADO实体查询绑定到gridview，但gridview触发的每个事件都会导致页面回发。每次页面回发时，数据源都为null，我必须再次绑定查询。

除了rowupdating事件之外，所有代码都可以找到显示和编辑数据。

我的问题在于，当rowupdating事件触发时，页面会回发一个帖子，我必须再次绑定数据，从而丢失我想要更新数据库的选定值。如果我不再绑定数据，则数据源为null，我的.findcontrol返回ArgumentOutOfRange异常。

我通过以下方式测试rowupdating事件中的其余代码：

1）在rowupdating事件上设置断点

2）点击更新超链接

3）使用SQL Server Management Studio更改表中的数据

4）继续执行代码

5）在SQL SMS中重新执行查询

此后，表格中的数据更新为旧值

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using HCA_QualityModel;


public partial class Admin : System.Web.UI.Page
{
    static HCA_QualityEntities database = new HCA_QualityEntities();
    static object grvMachinesQuery = (from m in database.Machines
                                      from d in database.Workcenters
                                      where m.WorkcenterFK == d.id
                                      select
                                          new { id = m.id, MachineName = m.MachineName, WorkCenterFK = d.WorkCenterName });
    protected void Page_Load(object sender, EventArgs e)
    {
        //bind the gridview on intial page load
        if (!Page.IsPostBack) bindGridViewData();
    }
    protected void bindGridViewData()
    {
        //Data binds for gridviews and ddl's

        grvMachines.DataSource = grvMachinesQuery;
        grvWorkCenters.DataSource = (from w in database.Workcenters select w);
        grvUsers.DataSource = (from u in database.Users select u);
        ddlAddDept.DataSource = grvWorkCenters.DataSource;
        ddlAddDept.DataValueField = "id";
        ddlAddDept.DataTextField = "WorkCenterName";
        DataBind();
    }
    //Adds new data to the db, then rebinds the griviews to the db
    #region Submit Buttons
    protected void btnSubmitMachine_Click(object sender, EventArgs e)
    {
        //add new machine to the database

        Machine temp = new Machine();
        temp.MachineName = txtAddMachine.Text;
        temp.WorkcenterFK = Int32.Parse(ddlAddDept.SelectedValue);
        database.Machines.AddObject(temp);
        database.SaveChanges();
        bindGridViewData();

    }
    protected void btnSubmitDept_Click(object sender, EventArgs e)
    {
        //add new workcenter to database

        Workcenter temp = new Workcenter();
        temp.WorkCenterName = txtAddDept.Text;
        database.Workcenters.AddObject(temp);
        database.SaveChanges();
        bindGridViewData();
    }
    protected void btnUserSubmit_Click(object sender, EventArgs e)
    {
        //add new user to the database

        HCA_QualityModel.User temp = new User();
        temp.Username = txtAddUser.Text;
        temp.Password = txtAddPassword.Text;
        database.Users.AddObject(temp);
        database.SaveChanges();
        bindGridViewData();
    }
    #endregion
    //Handles Updating, editing, and deleting Gridview Controls
    #region Gridview machines
    protected void grvMachines_RowDataBound(object sender, GridViewRowEventArgs e)
    {

        DropDownList temp = (DropDownList)(e.Row.FindControl("ddlDept"));
        if (temp != null)
        {
            temp.DataSource = (from w in database.Workcenters select w);
            temp.DataTextField = "WorkCenterName";
            temp.DataValueField = "id";
            temp.DataBind();
        }

    }
    protected void grvMachines_RowDeleting(object sender, GridViewDeleteEventArgs e)
    {

        int id = Int32.Parse(((Label)grvMachines.Rows[e.RowIndex].FindControl("lblId") as Label).Text);
        database.Machines.DeleteObject(((Machine)(from m in database.Machines where m.id == id select m).Single()));
        database.SaveChanges();
        bindGridViewData();
    }
    protected void grvMachines_RowCancelingEdit(object sender, GridViewCancelEditEventArgs e)
    {

        grvMachines.EditIndex = -1;
        bindGridViewData();
    }
    protected void grvMachines_RowEditing(object sender, GridViewEditEventArgs e)
    {
        grvMachines.EditIndex = e.NewEditIndex;
        bindGridViewData();
    }
    protected void grvMachines_RowUpdating(object sender, GridViewUpdateEventArgs e)
    {


        //Gridviews have no data on postback from events, rebinding looses the selected values from edit mode.

        bindGridViewData();

        DropDownList dept = (DropDownList)grvMachines.Rows[grvMachines.EditIndex].FindControl("ddlDept");
        TextBox name = (TextBox)grvMachines.Rows[grvMachines.EditIndex].FindControl("txtMachine");
        Int32 id = (Convert.ToInt32(((Label)grvMachines.Rows[grvMachines.EditIndex].FindControl("lblId")).Text));

        //Working Code to update the database, recieving incorrect data from controls due to rebinding 
        HCA_QualityEntities database = new HCA_QualityEntities();
        Machine temp = (from m in database.Machines where m.id == id select m).First();
        temp.MachineName = (name.Text);
        temp.WorkcenterFK = Int32.Parse(dept.SelectedValue);
        database.SaveChanges();
        grvMachines.EditIndex = -1;
        bindGridViewData();
    }
    #endregion
}

Asp代码

<%@ Page Title="" Language="C#" MasterPageFile="~/site.master" AutoEventWireup="true"
    CodeFile="Admin.aspx.cs" Inherits="Admin" %>

<asp:Content ID="Content1" ContentPlaceHolderID="head" runat="Server">
</asp:Content>
<asp:Content ID="Content2" ContentPlaceHolderID="ContentPlaceHolder1" runat="Server">
      <table style="width:800px; vertical-align:top;">
        <tr style="width:800px;">
           <td style="width:230px; height:90px;">
                Add New Machine:
                <br />
                &nbsp;Machine&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Dept
                <br />
                <asp:TextBox ID="txtAddMachine" runat="server" Width="70px"></asp:TextBox>
                <asp:DropDownList ID="ddlAddDept" runat="server" Width="110px">
                </asp:DropDownList>
                <br />
                <asp:Button ID="btnSubmitMachine" runat="server" Text="Submit" 
                onclick="btnSubmitMachine_Click" />
           </td>
           <td style="width:190px; height:90px;">
                Add New Dept:
                <br />
                Dept Name
                <br />
                <asp:TextBox ID="txtAddDept" runat="server" Width="100px"></asp:TextBox>
                <br />
                <asp:Button ID="btnSubmitDept" runat="server" Text="Submit" 
                onclick="btnSubmitDept_Click" />
           </td>
           <td style="width:250px; height:90px;"> 
                Add New User:
                <br />
                &nbsp;Username&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Password
                <br />
                <asp:TextBox ID="txtAddUser" runat="server" Width="90px"></asp:TextBox>
                <asp:TextBox ID="txtAddPassword" runat="server" Width="90px"></asp:TextBox>
                <br />
                <asp:Button ID="btnUserSubmit" runat="server" Text="Submit" 
                onclick="btnUserSubmit_Click" />
           </td>
        </tr>
        <tr style="width:800px; vertical-align:top;">
           <td style="width:230px;">
                <asp:GridView ID="grvMachines" runat="server" AutoGenerateColumns="False" 
                    Width="230px" onrowdeleting="grvMachines_RowDeleting" 
                    onrowediting="grvMachines_RowEditing" 
                    onrowcancelingedit="grvMachines_RowCancelingEdit" 
                    onrowupdating="grvMachines_RowUpdating" 
                    onrowdatabound="grvMachines_RowDataBound" 
                    EnableViewState="False">
                    <Columns>
                        <asp:TemplateField Visible="false">
                            <ItemTemplate>
                                <asp:Label ID="lblId" runat="server" Text='<%# Eval("id") %>'></asp:Label>
                            </ItemTemplate>
                            <EditItemTemplate>
                                <asp:Label ID="lblId" runat="server" Text='<%# Eval("id") %>'></asp:Label>
                            </EditItemTemplate>
                        </asp:TemplateField>
                        <asp:TemplateField HeaderText="Machine">
                            <ItemTemplate>
                                <asp:Label ID="lblMachine" runat="server" Text='<%# Eval("MachineName") %>'></asp:Label>
                            </ItemTemplate>
                            <EditItemTemplate>
                                <asp:TextBox ID="txtMachine" runat="server" Text='<%# Eval("MachineName") %>'></asp:TextBox>
                            </EditItemTemplate>
                            <ControlStyle Width="50px" />
                        </asp:TemplateField>
                        <asp:TemplateField HeaderText="Dept">
                            <ItemTemplate>
                                <asp:Label ID="lblDept" runat="server" Text='<%# Eval("WorkcenterFK") %>'></asp:Label>
                            </ItemTemplate>
                            <EditItemTemplate>
                                <asp:DropDownList ID="ddldept" runat="server">
                                </asp:DropDownList>
                            </EditItemTemplate>
                            <ControlStyle Width="120px" />
                        </asp:TemplateField>
                        <asp:CommandField HeaderText="Actions" ShowEditButton="true" ShowDeleteButton="True"
                            ControlStyle-Width="50px" CausesValidation="False" >
                        </asp:CommandField>
                    </Columns>
                </asp:GridView>
           </td>
           <td style="width:170px;">
                <asp:GridView ID="grvWorkCenters" runat="server" AutoGenerateColumns="False" 
                    Width="170px">
                    <Columns>
                        <asp:TemplateField HeaderText="id" Visible="false">
                            <ItemTemplate>
                                <asp:Label ID="lblId" runat="server" Text='<%# Eval("id") %>'></asp:Label>
                            </ItemTemplate>
                            <EditItemTemplate>
                                <asp:Label ID="lblId" runat="server" Text='<%# Eval("id") %>'></asp:Label>
                            </EditItemTemplate>
                        </asp:TemplateField>
                        <asp:TemplateField HeaderText="WorkCenter">
                            <ItemTemplate>
                                <asp:Label ID="lblWorkcenter" runat="server" Text='<%# Eval("WorkCenterName") %>'></asp:Label>
                            </ItemTemplate>
                            <EditItemTemplate>
                                <asp:TextBox ID="txtWorkcenter" runat="server" Text='<%# Eval("WorkCenterName") %>'></asp:TextBox>
                            </EditItemTemplate>
                            <ControlStyle Width="75px" />
                        </asp:TemplateField>
                        <asp:CommandField HeaderText="Actions" ShowEditButton="true" ShowDeleteButton="true"
                            ControlStyle-Width="50px" CausesValidation="False" />
                    </Columns>
                </asp:GridView>
           </td>
           <td style="width:290px;"> 
                <asp:GridView ID="grvUsers" runat="server" AutoGenerateColumns="False" 
                    Width="290px">
                <Columns>
                    <asp:TemplateField HeaderText="id" Visible="false">
                        <ItemTemplate>
                            <asp:Label ID="lblId" runat="server" Text='<%# Eval("id") %>'></asp:Label>
                        </ItemTemplate>
                        <EditItemTemplate>
                            <asp:TextBox ID="txtId" runat="server" Text='<%# Eval("id") %>'></asp:TextBox>
                        </EditItemTemplate>
                    </asp:TemplateField>
                    <asp:TemplateField HeaderText="User">
                        <ItemTemplate>
                            <asp:Label ID="lblUser" runat="server" Text='<%# Eval("Username") %>'></asp:Label>
                        </ItemTemplate>
                        <EditItemTemplate>
                            <asp:TextBox ID="txtUser" runat="server" Text='<%# Eval("Username") %>'></asp:TextBox>
                        </EditItemTemplate>
                        <ControlStyle Width="120px" />
                    </asp:TemplateField>
                    <asp:TemplateField HeaderText="Password">
                        <ItemTemplate>
                            <asp:Label ID="lblPassword" runat="server" Text='<%# Eval("Password") %>'></asp:Label>
                        </ItemTemplate>
                        <EditItemTemplate>
                            <asp:TextBox ID="txtPassword" runat="server" Text='<%# Eval("Password") %>'></asp:TextBox>
                        </EditItemTemplate>
                        <ControlStyle Width="120px" />
                    </asp:TemplateField>
                    <asp:CommandField HeaderText="Actions" ShowEditButton="true" ShowDeleteButton="true"
                        ControlStyle-Width="50px" CausesValidation="false" />
                </Columns>
            </asp:GridView>
           </td>
        </tr>
      </table>

</asp:Content>

Answer 1

我已经重构了你的源代码，现在应该可以了。

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using HCA_QualityModel;


public partial class Admin : System.Web.UI.Page
{
static HCA_QualityEntities database = new HCA_QualityEntities();
   protected void Page_Load(object sender, EventArgs e)
{
    //bind the gridview on intial page load
    if (!Page.IsPostBack) bindGridViewData();
}
protected void bindGridViewData()
{

 static object grvMachinesQuery = (from m in database.Machines
                                  from d in database.Workcenters
                                  where m.WorkcenterFK == d.id
                                  select
                                      new { id = m.id, MachineName = m.MachineName,  WorkCenterFK = d.WorkCenterName });

    //Data binds for gridviews and ddl's

    grvMachines.DataSource = grvMachinesQuery;
    grvWorkCenters.DataSource = (from w in database.Workcenters select w);
    grvUsers.DataSource = (from u in database.Users select u);
    ddlAddDept.DataSource = grvWorkCenters.DataSource;
    ddlAddDept.DataValueField = "id";
    ddlAddDept.DataTextField = "WorkCenterName";
    DataBind();
}

//Adds new data to the db, then rebinds the griviews to the db
#region Submit Buttons
protected void btnSubmitMachine_Click(object sender, EventArgs e)
{
    //add new machine to the database

    Machine temp = new Machine();
    temp.MachineName = txtAddMachine.Text;
    temp.WorkcenterFK = Int32.Parse(ddlAddDept.SelectedValue);
    database.Machines.AddObject(temp);
    database.SaveChanges();
    bindGridViewData();

}
protected void btnSubmitDept_Click(object sender, EventArgs e)
{
    //add new workcenter to database

    Workcenter temp = new Workcenter();
    temp.WorkCenterName = txtAddDept.Text;
    database.Workcenters.AddObject(temp);
    database.SaveChanges();
    bindGridViewData();
}
protected void btnUserSubmit_Click(object sender, EventArgs e)
{
    //add new user to the database

    HCA_QualityModel.User temp = new User();
    temp.Username = txtAddUser.Text;
    temp.Password = txtAddPassword.Text;
    database.Users.AddObject(temp);
    database.SaveChanges();
    bindGridViewData();
}
#endregion
//Handles Updating, editing, and deleting Gridview Controls
#region Gridview machines
protected void grvMachines_RowDataBound(object sender, GridViewRowEventArgs e)
{

    DropDownList temp = (DropDownList)(e.Row.FindControl("ddlDept"));
    if (temp != null)
    {
        temp.DataSource = (from w in database.Workcenters select w);
        temp.DataTextField = "WorkCenterName";
        temp.DataValueField = "id";
        temp.DataBind();
    }

}
protected void grvMachines_RowDeleting(object sender, GridViewDeleteEventArgs e)
{

    int id = Int32.Parse(((Label)grvMachines.Rows[e.RowIndex].FindControl("lblId") as Label).Text);
    database.Machines.DeleteObject(((Machine)(from m in database.Machines where m.id == id select m).Single()));
    database.SaveChanges();
    bindGridViewData();
}
protected void grvMachines_RowCancelingEdit(object sender, GridViewCancelEditEventArgs e)
{

    grvMachines.EditIndex = -1;
    bindGridViewData();
}
protected void grvMachines_RowEditing(object sender, GridViewEditEventArgs e)
{
    grvMachines.EditIndex = e.NewEditIndex;
    bindGridViewData();
}
protected void grvMachines_RowUpdating(object sender, GridViewUpdateEventArgs e)
{


    //Gridviews have no data on postback from events, rebinding looses the selected values from edit mode.

    bindGridViewData();

    DropDownList dept = (DropDownList)grvMachines.Rows[grvMachines.EditIndex].FindControl("ddlDept");
    TextBox name = (TextBox)grvMachines.Rows[grvMachines.EditIndex].FindControl("txtMachine");
    Int32 id = (Convert.ToInt32(((Label)grvMachines.Rows[grvMachines.EditIndex].FindControl("lblId")).Text));

    //Working Code to update the database, recieving incorrect data from controls due to rebinding 
    HCA_QualityEntities database = new HCA_QualityEntities();
    Machine temp = (from m in database.Machines where m.id == id select m).First();
    temp.MachineName = (name.Text);
    temp.WorkcenterFK = Int32.Parse(dept.SelectedValue);
    database.SaveChanges();
    grvMachines.EditIndex = -1;
    bindGridViewData();
}
#endregion

}

Answer 2

您可以暂时断开事件处理程序吗？

myGridView.rowUpdating -= myGridView_rowUpdating;
//code to populate
myGridView.rowUpdating += myGridView_rowupdating;

或C# Disable Event Handler Problem

我有一个不稳定的验证块，我试图重构一个工作，当我不想要它们并使它们重新绑定时我的dataBindings刷新，然后重新绑定然后我最终在这个递归-y汤中。我只有一个实例，所以我只关闭了事件处理程序并重新启用它。