为SqlDataSource的编程不适合回传ASP.NET工作设置参数 [英] ASP.NET Setting parameter for SqlDataSource programatically does not work for postback

问题描述

我要设置一个SqlDataSource编程参数作为<一个步骤5中所述href=\"http://www.asp.net/data-access/tutorials/using-parameterized-queries-with-the-sqldatasource-vb\" rel=\"nofollow\">http://www.asp.net/data-access/tutorials/using-parameterized-queries-with-the-sqldatasource-vb 。另外一个GridView绑定到SqlDataSource控件。我的标记是：

I want to set a parameter for a SqlDataSource programmatically as described in Step 5 at http://www.asp.net/data-access/tutorials/using-parameterized-queries-with-the-sqldatasource-vb . Also a GridView is bound to the sqlDataSource. My markup is:

<asp:SqlDataSource ID="mySqlDataSource" runat="server" 
    ConnectionString="<%$ ConnectionStrings:ConnectionStringHTL %>" 
    SelectCommand="SELECT [subscription_con] FROM [HTL_CONSUME_CON] WHERE ([subscription_con] = @subscription_con)">
    <SelectParameters>
        <asp:Parameter Name="subscription_con" Type="Int32" />
    </SelectParameters>
</asp:SqlDataSource>
<asp:GridView ID="myGridView" runat="server" AllowPaging="True" 
    AllowSorting="True" DataSourceID="mySqlDataSource">
</asp:GridView>

在codebehind，我有：

In the codebehind, I have:

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load    
    mySqlDataSource.SelectParameters("subscription_con").DefaultValue = calcResult()
End Sub

从calcResult（）的返回值是每次回发不同。当用户点击一个具有UseSubmitBehavior表单上的按钮时，会出现回发= TRUE。

The return value from calcResult() is different for each postback. The postback occurs when the user clicks a Button on the form that has UseSubmitBehavior=True.

我已经使用调试器来逐步落后于code和我看到它的每一页加载执行，我看到预期值从clacResult（）。

I've use the debugger to step through the code behind and I see it executed for each page load and I see the expected values returned from clacResult().

但所绑定的DataGrid从不更新的回传，它仅在第一个页面加载更新。

However the bound DataGrid is never updated on the postbacks, it only updates on the first page load.

如果我改变SqlDataSource的参数有一个控制为源，那么它的工作原理上回发。在otherwords，我改变了标记的使用方法：

If I change the SqlDataSource parameter to have a control as the source, then it works on postbacks. In otherwords, I changed the markup to use:

<asp:ControlParameter ControlID="myTextBox" Name="subscription_con" PropertyName="Text" Type="Int32" />

和我换了code后面的是：

and I changed the code behind to be:

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load    
   myTextBox.Text = calcResult()
End Sub

使用TextBox控件作为参数的SqlDataSource之源，在GridView的更新工程，为原来的页面加载和所有回发。不过，我实在是没有必要的文本框，并会preFER不使用它。

With the TextBox control as the source of the SqlDataSource parameter, update of the GridView works for the original page load and all postbacks. However, I really have no need for the TextBox and would prefer not to use it.

我缺少有关如何为将SqlDataSource编程设置的参数？为什么不以编程方式设置在SqlDataSource参数时，当没有控制源绑定的GridView控件得到更新上回发？

What am I missing about how to set a parameter programmatically for an SqlDataSource? Why doesn't the bound GridView get updated on postbacks when setting the SqlDataSource parameter programmatically when there is no control source?

推荐答案

您可能需要在回发的露骨databaind：

You may need an explict databaind on postbacks:

if (Page.IsPostBack)
{
    grid.DataBind();
}

应该这样做。

这篇关于为SqlDataSource的编程不适合回传ASP.NET工作设置参数的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！