Question

在我的asp页面中，我使用了两个gridview。并在页面加载事件中将数据绑定到这些gridview。但它显示"System.NullReferenceException: Object reference not set to an instance of an object.": 并在此行获得例外

GridReturned.DataSource = ds2;

这是我的代码

<asp:Accordion ID="Accordion1" runat="server" SelectedIndex="0" AutoSize="None"
            FadeTransitions="true" TransitionDuration="300" FramesPerSecond="25">
            <Panes>
                <asp:AccordionPane ID="AccordionPane1" runat="server">
                    <Header>
                        <br />
                        <div class="headPane">
                            Issued History
                        </div>
                    </Header>
                    <Content>
                        <div class="bodyPane">
                            <asp:UpdatePanel ID="UpdatePanel1" runat="server">
                                <ContentTemplate>
                                    <asp:GridView ID="GridIssue" runat="server" CssClass="grid" AllowPaging="true" PageSize="8" OnPageIndexChanging="GridIssue_PageIndexChanging">
                                        <EmptyDataTemplate>
                                            <p style="margin-left: 10px;">No Book Has Been Issued Yet.</p>
                                        </EmptyDataTemplate>
                                    </asp:GridView>

                                </ContentTemplate>
                            </asp:UpdatePanel>
                        </div>
                    </Content>
                </asp:AccordionPane>
                <asp:AccordionPane runat="server" ID="acd2">
                    <Header>
                        <div class="headPane">
                            Restore Books
                        </div>
                    </Header>
                    <Content>
                        <div class="bodyPane">
                            <asp:GridView ID="GridReturned" runat="server" OnSelectedIndexChanged="GridReturned_SelectedIndexChanged">
                                <EmptyDataTemplate>
                                    <p>Books Are Not Required To Return At Present.</p>
                                </EmptyDataTemplate>
                                <Columns>
                                    <asp:CommandField ButtonType="Button" SelectText="Return" ShowSelectButton="true" />
                                </Columns>
                            </asp:GridView>
                        </div>
                    </Content>
                    <Content>
                    </Content>
                </asp:AccordionPane>
            </Panes>
        </asp:Accordion>

后面的代码如下

   string str = ConfigurationManager.ConnectionStrings["connect"].ConnectionString;
    SqlConnection con;
    SqlCommand cmd;
    string getQuery;
    protected void Page_Load(object sender, EventArgs e)
    {
        getQuery = "select Issue_ID as 'Issue Id', IssueDate as 'Issue Date', ReturnDate as 'Return Date' , UserName as 'User Name' , BookName as 'Book Name', Category ,ActualReturnDate from IssueRecords";
       getData(getQuery,0);
       getQuery = "select Issue_ID,BID,UserName,BookName,IssueDate,ReturnDate from IssueRecords where ActualReturnDate is null";
       getData(getQuery, 1);
    }
    public void getData(string query, int i)
    {
        con = new SqlConnection(str);

        cmd = new SqlCommand(query, con);
        if (i == 0)
        {
            con.Open();
            SqlDataAdapter da = new SqlDataAdapter(cmd);
            DataSet ds = new DataSet();
            da.Fill(ds);
            GridIssue.DataSource = ds;
            GridIssue.DataBind();
            con.Close();
        }
        else
        {
            con.Open();
            SqlDataAdapter da2 = new SqlDataAdapter(cmd);
            DataSet ds2 = new DataSet();
            da2.Fill(ds2);
            GridReturned.DataSource = ds2;
            GridReturned.DataBind();
            con.Close();
        }

    }

是否有任何事件行更改页面手风琴索引，以便我可以在更改事件时触发这些事件。

Answer 1

   <div id="content">
        <asp:Accordion ID="Accordion1" runat="server" SelectedIndex="0" AutoSize="None"
            FadeTransitions="true" TransitionDuration="300" FramesPerSecond="25">
            <Panes>
                <asp:AccordionPane ID="AccordionPane1" runat="server">
                    <Header>
                        <br />
                        <div class="headPane">
                            Issued History
                        </div>
                    </Header>
                    <Content>
                        <div class="bodyPane">
                            <asp:UpdatePanel ID="UpdatePanel1" runat="server">
                                <ContentTemplate>
                                    <asp:GridView ID="GridIssue" runat="server" CssClass="grid" AllowPaging="true" PageSize="8" OnPageIndexChanging="GridIssue_PageIndexChanging">
                                        <EmptyDataTemplate>
                                            <p style="margin-left: 10px;">No Book Has Been Issued Yet.</p>
                                        </EmptyDataTemplate>
                                    </asp:GridView>

                                </ContentTemplate>
                            </asp:UpdatePanel>
                        </div>
                    </Content>
                </asp:AccordionPane>
                <asp:AccordionPane runat="server" ID="acd2">
                    <Header>
                        <div class="headPane">
                            Restore Books
                        </div>
                    </Header>
                    <Content>
                        <div class="bodyPane">
                           <asp:GridView ID="GridReturned" DataSourceID="sdSource" runat="server" OnSelectedIndexChanged="GridReturned_SelectedIndexChanged">
                                <EmptyDataTemplate>
                                    <p>Books Are Not Required To Return At Present.</p>
                                </EmptyDataTemplate>
                                <Columns>
                                    <asp:CommandField ButtonType="Button" SelectText="Return" ShowSelectButton="true" />
                                </Columns>
                            </asp:GridView>
                            <asp:SqlDataSource ID="sdSource" runat="server" SelectCommand="select Issue_ID,BID,UserName,BookName,IssueDate,ReturnDate from IssueRecords where ActualReturnDate is null" ConnectionString="<%$ConnectionStrings:connect %>" ></asp:SqlDataSource>
                        </div>
                    </Content>

                </asp:AccordionPane>
            </Panes>
        </asp:Accordion>

你调用的对象是空的。在手风琴控制中

1 个答案: