How to handle exceptions with a SqlDataSource

问题:

I have a SqlDataSource that is supplying data to my GridView. Thats all i am using on my form, thus i have NO code behind at all. But somewhere i need a TRY CATCH block just in case my connection get's lost. What code must i place where?

If i get a error i want my lblMessage Text to be "No connection".

Edit

My GridView in my Machine.aspx

<asp:GridView ID="GridView1" runat="server" AllowPaging="True" AutoGenerateColumns="False" 
    Height="209px" PageSize="7" Width="331px" AllowSorting="True" 
                DataSourceID="SqlDataSource1">
    <Columns>
        <asp:BoundField DataField="Total" HeaderText="Total" ReadOnly="True" 
            SortExpression="Total" DataFormatString="{0:R#,###,###}" >
            <HeaderStyle HorizontalAlign="Left" />
        </asp:BoundField>
        <asp:BoundField DataField="b134_rmcid" HeaderText="Machine"  ReadOnly="True" 
            SortExpression="b134_rmcid" >
            <HeaderStyle HorizontalAlign="Left" />
        </asp:BoundField>
        <asp:BoundField DataField="b134_recdate" DataFormatString="{0:d/MM/yyyy}" 
            HeaderText="Date" ReadOnly="True" SortExpression="b134_recdate" >
            <HeaderStyle HorizontalAlign="Left" />
        </asp:BoundField>
    </Columns>
</asp:GridView>

My Connection right under my Gridview in my Machine.aspx

<asp:SqlDataSource ID="SqlDataSource1" runat="server" 
    ConnectionString="<%$ ConnectionStrings:ODBC_ConnectionString %>" 
    ProviderName="<%$ ConnectionStrings:ODBC_ConnectionString.ProviderName %>" 

    SelectCommand="SELECT SUM(b134_nettpay) AS Total, b134_rmcid, b134_recdate FROM B134HRE" 
    onselected="SqlDataSource1_Selected">

</asp:SqlDataSource>

My Code in my Code Behind file in my Machine.aspx.cs

protected void Page_Load(object sender, EventArgs e)
{
    lblError.Text = "hello there";
    SqlDataSource1.Selected += new SqlDataSourceStatusEventHandler(SqlDataSource1_Selected);


}


protected void SqlDataSource1_Selected(object sender, SqlDataSourceStatusEventArgs e)
{

  if (e.ExceptionHandled)
   {

       lblError.Text = "There is a problem";  

   }

}

And still for some ready when i place a BreakPoint in my Selected Event it does not even get to it???

Why?

回答1:

The SqlDataSource has an Selected event. Add a handler to this event like so, and handle any errors (show an informative message etc) in this handler.

void GridView1_Selected(object sender, SqlDataSourceStatusEventArgs e)
{
    if (e.ExceptionHandled)
    {
        //Show error message
    }
}

Sorry, but you're going to have to have some code in the code-behind!

Edit

Looking at your code, I don't think you're ever binding your GridView, so your SqlDataSource is never trying to select the data from your database.

In your Page_Load method, add the following code:

    if (!IsPostBack)
    {
        GridView1.DataBind();
    }

Further edit

Try changing "onselected" to "OnSelected" on your SqlDataSource and remove the line to bind your event handler in the code behind.

I'm stumped if that doesn't work as you've basically got the simplest-possible example.

Even further edit

Try this instead

void SqlDataSource1_Selected(object sender, SqlDataSourceStatusEventArgs e)
{
    if (e.Exception != null)
    {
        //Show error message
        lblError.Text = "There is a problem"; 

        //Set the exception handled property so it doesn't bubble-up
        e.ExceptionHandled = true;
    }
}

回答2:

you need to handle the error from code behind of your Gridview_ItemInserting or gridview_itemupdating so as to fire before your code are submitted to the sql control.

protected void GridView1_ItemInserting(object sender,DetailsViewInsertEventArgs e)
{
if (e.Exception != null)
{
Lblerror.text="error message"
}
}

do so also for updating

回答3:

I believe you want to handle the Selected event of the SQLDataSource, and check the event argument for the exception.

回答4:

Create an event handler for the Selected event of the SqlDataSource, test if an exception occurred, perform whatever error reporting you want, then indicate that you've now handled the error.

    mSqlDataSource.Selected += new sqlDataSourceStatusEventHandler(mSqlDataSource_Selected);


    void mSqlDataSource_Selected(object sender, SqlDataSourceStatusEventArgs e)
    {
        if (e.Exception != null)
        {
            mErrorText.Text = e.Exception.Message;
            mErrorText.Visible = true;
            e.ExceptionHandled = true;
        }
    }

回答5:

void SqlDataSource1_Selected(object sender, SqlDataSourceStatusEventArgs e)
{
if (e.Exception = null)
{
//bind data to gridview
GridView1.DataBind();
}
else
{
//Show error message    
lblError.Text = "There is a problem";
//Set the exception handled property so it doesn't bubble-up
e.ExceptionHandled = true;
}
}