gridview控件不刷新？

Question

我希望有一個簡單的問題。 我有一個綁定到sqldatasource的gridview控件。

一，相關代碼：

<asp:DropDownList ID="cboCustomerID" runat="server"
    DataSourceID="DataSourceCustomer" DataTextField="CustomerName" DataValueField="CustomerID">
</asp:DropDownList>
<asp:DropDownList ID="cboStaffID" runat="server"
    DataSourceID="DataSourceStaff" DataTextField="StaffFullName" DataValueField="StaffID">
</asp:DropDownList>
<div><gcctl:MyCheckBox ID="chkShowClosed" Text="Show Closed Jobs?" Checked="false" AutoPostBack="true" runat="server" /></div>
<div><asp:Button ID="btnSearch" runat="server" OnClick="btnSearch_Click" Text="Search" /></div>

<div id="customersearchresults" class="searchresults">
    <asp:SqlDataSource id="gvJobsDataSource" runat="server" ConnectionString="<%$ ConnectionStrings:GeekCommandConnString %>"
        SelectCommand="SELECT j.JobID, j.JobName, s.JobStatus, jal.[JobAssignmentsFullList]
            FROM (SELECT * FROM [dbo].[Jobs] WHERE ((NULLIF(@CustomerSearch,'') IS NOT NULL AND CustomerID = @CustomerSearch) OR (NULLIF(@CustomerSearch,'') IS NULL))) j
            INNER JOIN (SELECT * FROM [list].[JobStatuses] WHERE ((@ShowClosed = 0 AND IsStatusOpen = 1) OR (@ShowClosed = 1)) AND IsActive = 1) s ON j.JobStatusID = s.JobStatusID
            LEFT JOIN (SELECT * FROM [dbo].[JobAssignments] WHERE ((NULLIF(@StaffSearch,'') IS NOT NULL AND StaffID = @StaffSearch) OR (NULLIF(@StaffSearch,'') IS NULL))) ja ON j.JobID = ja.JobID
            LEFT JOIN [dbo].[udv_JobAssignmentsCommaDelimited] jal ON j.JobID = jal.JobID
            ">
        <SelectParameters>
            <asp:Parameter Name="CustomerSearch" Type="Int32" />
            <asp:Parameter Name="StaffSearch" Type="Int32" />
            <asp:Parameter Name="ShowClosed" Type="Boolean" />
        </SelectParameters>
    </asp:SqlDataSource>

    <asp:GridView ID="gvJobs" runat="server" AllowSorting="True"  
        AutoGenerateColumns="False"
        DataKeyNames="JobID"
        DataSourceID="gvJobsDataSource"
        AutoGenerateDeleteButton="False"    
        AutoGenerateEditButton="False" 
        AutoGenerateSelectButton="False"
        CssClass="searchresultsgrid" 
        AllowPaging="True" PageSize="50"
        OnRowCommand="gvJobs_RowCommand"
        EmptyDataText="No matching jobs on record." >
        <Columns>
            <asp:templatefield>
                <itemtemplate>
                    <asp:linkbutton id="btnEdit" runat="server" CommandName="JobEdit" OnClientClick="PageForm.target ='_blank';" text="View/Edit" />
                </itemtemplate>
            </asp:templatefield>

            <asp:BoundField DataField="JobID" HeaderText="ID" InsertVisible="false" ReadOnly="true" Visible="false" SortExpression="JobID" />
            <asp:templateField HeaderText="Job Name" SortExpression="JobName">
                <ItemTemplate><%# Eval("JobName") %></ItemTemplate>
            </asp:templateField>
            <asp:templateField HeaderText="Assigned to" SortExpression="JobAssignmentsFullList">
                <ItemTemplate><%# Eval("JobAssignmentsFullList") %></ItemTemplate>
            </asp:templateField>
        </Columns>
    </asp:GridView>
</div>


<asp:SqlDataSource ID="DataSourceCustomer" runat="server"
    ConnectionString="<%$ ConnectionStrings:GeekCommandConnString %>" 
    SelectCommand="SELECT NULL AS [CustomerID]
                , NULL AS [CustomerName]
            UNION SELECT [CustomerID]
                ,[CustomerName]
            FROM [GeekCommand].[dbo].[Customers]
            WHERE ((@ShowInactive = 0 AND IsActive = 1) OR (@ShowInactive = 1))
            ORDER BY CustomerName">
    <SelectParameters>
        <asp:ControlParameter Name="ShowInactive" Type="Boolean" ControlID="chkCustomersShowInactive" PropertyName="Checked" />
    </SelectParameters>
</asp:SqlDataSource>
<asp:SqlDataSource ID="DataSourceStaff" runat="server"
    ConnectionString="<%$ ConnectionStrings:GeekCommandConnString %>" 
    SelectCommand="SELECT NULL AS [StaffID]
                , NULL AS [StaffFullName]
            UNION SELECT [StaffID]
                ,COALESCE([FirstName], [Nickname], '') + ' ' + COALESCE([LastName], '') AS StaffFullName
            FROM [GeekCommand].[dbo].[Staff]
            WHERE ((@ShowInactive = 0 AND IsActive = 1) OR (@ShowInactive = 1))
            ORDER BY StaffFullName">
    <SelectParameters>
        <asp:ControlParameter Name="ShowInactive" Type="Boolean" ControlID="chkStaffShowInactive" PropertyName="Checked" />
    </SelectParameters>
</asp:SqlDataSource>

以及相關的aspx.cs代碼：

int? iCustomerID;
int? iStaffID;

//--------
protected void SetIDs()
{
    this.iCustomerID = null;
    this.iStaffID = null;

    if (Request.QueryString["customerid"] != null) //new customer
    {
        try
        {
            this.iCustomerID = Convert.ToInt32(Request.QueryString["customerid"]);
        }
        catch { }
    }

    if (Request.QueryString["staffid"] != null) //new customer
    {
        try
        {
            this.iStaffID = Convert.ToInt32(Request.QueryString["staffid"]);
        }
        catch { }
    }

    if (iCustomerID != null)
    {
        cboCustomerID.SelectedValue = iCustomerID.ToString();
    }

    if (iStaffID != null)
    {
        cboStaffID.SelectedValue = iStaffID.ToString();
    }
}

//--------
protected void Page_Load(object sender, EventArgs e)
{
    if (!IsPostBack)
    {
        SetIDs();
    }
}

//--------
protected void btnSearch_Click(object sender, EventArgs e)
{
    gvJobsDataSource.SelectParameters["CustomerSearch"].DefaultValue = cboCustomerID.SelectedValue.ToString();
    gvJobsDataSource.SelectParameters["StaffSearch"].DefaultValue = cboStaffID.SelectedValue.ToString();
    gvJobsDataSource.SelectParameters["ShowClosed"].DefaultValue = chkShowClosed.Checked.ToString();

    gvJobs.DataBind();
}

當我在SSMS中運行以下命令時，我應該返回2行：

DECLARE @CustomerSearch int, @StaffSearch int, @ShowClosed bit
SELECT @CustomerSearch = 2331, @StaffSearch = '', @ShowClosed = CAST(0 AS bit)

SELECT j.JobID, j.JobName, s.JobStatus, jal.[JobAssignmentsFullList]
FROM (SELECT * FROM [dbo].[Jobs] WHERE ((NULLIF(@CustomerSearch,'') IS NOT NULL AND CustomerID = @CustomerSearch) OR (NULLIF(@CustomerSearch,'') IS NULL))) j
INNER JOIN (SELECT * FROM [list].[JobStatuses] WHERE ((@ShowClosed = 0 AND IsStatusOpen = 1) OR (@ShowClosed = 1)) AND IsActive = 1) s ON j.JobStatusID = s.JobStatusID
LEFT JOIN (SELECT * FROM [dbo].[JobAssignments] WHERE ((NULLIF(@StaffSearch,'') IS NOT NULL AND StaffID = @StaffSearch) OR (NULLIF(@StaffSearch,'') IS NULL))) ja ON j.JobID = ja.JobID
LEFT JOIN [dbo].[udv_JobAssignmentsCommaDelimited] jal ON j.JobID = jal.JobID

但是，當我在調試模式下選擇一個客戶（特別是ID為2331的客戶）並逐步檢查btnSearch_Click代碼時，cboCustomerID.SelectedValue =“ 2331”，cboStaffID.SelectedValue =“”，chkShowClosed.Checked = false（所有這些都是正確）...但是當我通過databind命令時什么也沒有發生。 網格視圖繼續顯示“記錄中沒有匹配的作業”。

我覺得自己缺少真正明顯的東西，但是我無法終生弄清楚它是什么。

更新：好的。 這是有趣的。 顯然，查詢永遠不會發送到SQL Server。 我剛剛以跟蹤模式啟動SQL Server，重新加載了aspx頁面，然后進行了搜索，雖然兩個下拉列表后面的查詢都在日志中，但是gridview后面的查詢卻不存在。

更新2：我已將select參數替換為以下內容：

<asp:ControlParameter Name="CustomerSearch" ControlID="cboCustomerID" PropertyName ="SelectedValue" />
<asp:ControlParameter Name="StaffSearch" ControlID="cboStaffID" PropertyName ="SelectedValue" />
<asp:ControlParameter Name="ShowClosed" Type="Boolean" ControlID="chkShowClosed" PropertyName="Checked" />

...並刪除了btnSearch_Click事件中的多余代碼，因此該代碼中的唯一一行是：

protected void btnSearch_Click(object sender, EventArgs e)
{
    gvJobs.DataBind();
}

...沒變。 當我單擊搜索按鈕時，仍然沒有任何反應。

Answer 1

好極了！ 找到了答案： https : //forums.asp.net/t/1243253.aspx?Gridview+Databind+Not+Working

問題是gridviews具有屬性：CancelSelectOnNullParameter，默認情況下為true。 由於在執行搜索時，至少有一個下拉列表幾乎總是為空，因此當我按下搜索按鈕時，什么也沒有發生。 當我將CancelSelectOnNullParameter =“ false”添加到gridview控件時，它解決了該問題。

（半相關的注釋）我還向ControlParameters中添加了以下內容：ConvertEmptyStringToNull =“ true”