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Gridview RowUpdating Exception Handling

Posted on 2008-10-02
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Last Modified: 2013-11-11
I am attempting to update an SQL 2005 table from a gridview.  The table has a unique index on two fields, PersonID and EmailTypeID.

I can update a record successfully if the record is indeed unique:

PersonID     EmailTypeID
123             1
123             2
123             3

the record is committed to the DB and all is well.

If I attempt to update and violate the unique index such as:
PersonID     EmailTypeID
123             1
123             2
123             2

I get no response in the web page.  The update simply does not happen, but there is no indication on the page that there is a problem.

If I run Query Analyzer and run the generated SQL captured from Profiler, I get the obvious:
 "Cannot insert duplicate key row"

I tried to use:
    Protected Sub grdEmails_RowUpdating(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.GridViewUpdateEventArgs) Handles grdEmails.RowUpdating

    End Sub

but I can't seem to expose any exception class from e.

I am using a LinqDataSource... and I only have two properties in my codebehind

How can I trap the exception?

Thanks,
Aaron

<asp:UpdatePanel ID="UpdatePanel1" runat="server">
<ContentTemplate>
<asp:GridView ID="grdEmails" runat="server" AutoGenerateColumns="False" DataSourceID="ldsPersonEmails" 
    DataKeyNames="EmailRecordID" OnRowUpdating="UpdateEmails">
    <Columns>
        <asp:CommandField ShowDeleteButton="True" ShowEditButton="True" EditText="edit" DeleteText="delete" />
        <asp:TemplateField HeaderText="Email">
            <EditItemTemplate>
                <asp:TextBox ID="txtEditEmailAddress" runat="server" Text='<%# Bind("EmailAddress")%>' ></asp:TextBox>
            </EditItemTemplate>
            <FooterTemplate>
                Add
                <asp:TextBox ID="txtNewEmailAddress1" runat="server"></asp:TextBox>
            </FooterTemplate>
            <ItemTemplate>
                <asp:HyperLink ID="hlkEmailAddress" runat="server" NavigateUrl='<%# Eval("EmailAddress", "mailto:{0}") %>'
                    Text='<%# Eval("EmailAddress") %>'>
                </asp:HyperLink>
            </ItemTemplate>
        </asp:TemplateField>
        <asp:TemplateField HeaderText="Type">
            <FooterTemplate>
                <asp:DropDownList ID="ddlEmailTypes1" DataSourceID="ldsEmailTypes" DataValueField="EmailTypeID"
                    DataTextField="EmailDescription"  runat="server">
                </asp:DropDownList>
            </FooterTemplate>
            <ItemTemplate>
                <%#Eval("email_type.EmailDescription")%>
            </ItemTemplate>
            <EditItemTemplate>
                <asp:DropDownList ID="ddlEmailTypes2" DataSourceID="ldsEmailTypes" DataValueField="EmailTypeID"
                    DataTextField="EmailDescription" SelectedValue='<%#Bind("EmailTypeID")%>' runat="server">
                </asp:DropDownList>
            </EditItemTemplate>
        </asp:TemplateField>
    </Columns>
    <EmptyDataTemplate>
        No email addresses on file.<br />
        <br />
        Add a new email address:<br />
        <asp:TextBox ID="txtNewEmailAddress2" runat="server"></asp:TextBox>
        <asp:DropDownList ID="ddlEmailTypes3" DataSourceID="ldsEmailTypes" DataValueField="EmailTypeID"
                    DataTextField="EmailDescription"  runat="server">
        </asp:DropDownList>
        <asp:LinkButton ID="lnkAddNewEmailEmptyData" runat="server">Add</asp:LinkButton>
    </EmptyDataTemplate>
</asp:GridView>
<asp:LinqDataSource ID="ldsPersonEmails" runat="server" ContextTypeName="VBCODE.jhadbDataClassesDataContext"
    TableName="person_emails" Where="PersonID == @PersonID" EnableDelete="True" EnableInsert="True"
    EnableUpdate="True">
    <WhereParameters>
        <asp:QueryStringParameter Name="PersonID" QueryStringField="PersonID" Type="Int32" />
    </WhereParameters>
</asp:LinqDataSource>
<asp:LinqDataSource ID="ldsEmailTypes" ContextTypeName="VBCODE.jhadbDataClassesDataContext"
    TableName="email_types" runat="server">
</asp:LinqDataSource>
</ContentTemplate>
</asp:UpdatePanel>

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Question by:abenage
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4 Comments
 
LVL 12

Expert Comment

by:madhevan_pillai
ID: 22658125
Hi

Did you get any exception like the below
Could not find a row that matches the given keys in the original values stored in ViewState.  Ensure that the 'keys' dictionary contains unique key values that correspond to a row returned from the previous Select operation.
0
 
LVL 1

Author Comment

by:abenage
ID: 22659471
I think I have ran into that problem and I needed to make sure there was a unique column on the database table.  For example, I was using the PersonID and EmailTypeID columns for the primary key.  What I had to do was create a EmailRecordID column, type INT, Identity True and set that as the Primary key.  I then used the other two columns to create a unique index.  Then, in my gridview, I set the DataKeyNames to the new EmailRecordID column.  Does this help you?
0
 
LVL 4

Accepted Solution

by:
novynov earned 2000 total points
ID: 22670543
Using the controls that you mentioned (LinqDataSource / GridView), there are 3 events during update that expose an exception:

- LinqDataSource.OnUpdating - LinqDataSourceUpdateEventArgs.Exception
- LinqDataSource.OnUpdated - LinqDataSourceStatusEventArgs.Exception
-GridView.OnRowUpdated - GridViewRowUpdatedEventArgs.Exception

The GridView.OnRowUpdating does not expose one.

That said, I believe an exception due to a violation of a constraint (e.g. FK) will be trappable both on LinqDataSource.OnUpdated as well as GridView.OnRowUpdated.

On each of those events, there is an ExceptionHandled property that you can set to true if you want the exception to cease bubbling up.

Please let me know if this doesn't answer your question. I'll be glad to help.




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LVL 1

Author Comment

by:abenage
ID: 22679454
I got it with LinqDataSource.OnUpdating.  Thanks!
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