Custom validator message not displaying

问题:

• VS2013, WebForms, .NET 4.51

I have a FormView defined and in my EditTemplate I have as follows:

 <div class="form-group">
    <asp:Label ID="lblClientClassification" CssClass="col-md-2 control-label" runat="server" for="cblClientClassifications" Text="Kind"></asp:Label>
     <div class="col-md-5">
         <asp:CheckBoxList ID="cblClientClassifications" runat="server"></asp:CheckBoxList>
         <asp:CustomValidator ID="cfvClientKinds" runat="server" Display="Dynamic" CssClass="label label-danger" ErrorMessage="XXXX" ValidationGroup="Default" OnServerValidate="cfvClientClassifications_OnServerValidate"></asp:CustomValidator>
 </div>

and then in the code behind:

    protected void cfvClientClassifications_OnServerValidate(object aSource, ServerValidateEventArgs aArgs)
    {
        CustomValidator cvCheckBoxKinds = aSource as CustomValidator;
        int checkedCount = 0;
        if (cvCheckBoxKinds != null)
        {
            CheckBoxList cblClientClassifications = GuiClientClassificationsFind();
            foreach (ListItem listItem in cblClientClassifications.Items)
            {
                if (listItem.Selected)
                {
                    checkedCount++;
                }
            }

            if (checkedCount == 0)
            {
                aArgs.IsValid = false;
                cvCheckBoxKinds.ErrorMessage = "Select client kind.";
            }
        }
    }

The OnServerValidate is firing and I am getting to set the validator to invalid as well as setting the error message (Page.IsValid is also false as expected). However, the error text is not displaying. When I view the page source I see:

<span id="ctl00_cphMainContent_fvData_cfvClientKinds" class="label label-danger" style="display:none;">XXXX</span>

instead of the error message I set as well as the fact that it is not visible.

Has anyone got any pointers here on how to track this down? I have looked at similar questions of SO but none of the comments seem to apply. Is this related to FormView perhaps?

回答1:

Try your control without the CssClass="label label-danger" bootstrap first, and use the code below to check your boxes:

    protected void cfvClientKinds_ServerValidate(object aSource, ServerValidateEventArgs aArgs)
    {
        aArgs.IsValid = cblClientClassifications.SelectedItem != null;
        cfvClientKinds.ErrorMessage = "Hey! this is a new message";
    }

and I guess you call this line before you fire the above event:

    protected void btnValidate_Click(object sender, EventArgs e)
    {
        Page.Validate();
    }

回答2:

In Short, I think that your problem is either related to your way of finding cblClientClassifications checkBoxList or other code that you haven't stated above.

CheckBoxList cblClientClassifications = GuiClientClassificationsFind();

I decided to try out your case and created a new webform added formview and bind it to northwind categories table then inside edititemtemplate I added a checkboxlist and populated it manually. added CustomValidator double clicked it copied your codebehind and it works for me except for the findcontrol part: GuiClientClassificationsFind(); Here is the formview:

<asp:FormView ID="FormView1" runat="server" DataKeyNames="CategoryID" DataSourceID="SqlDataSource1">
    <EditItemTemplate>
        ...
        <asp:CheckBoxList ID="cblClientClassifications" runat="server">
            <asp:ListItem>Bir</asp:ListItem>
            <asp:ListItem>iki</asp:ListItem>
            <asp:ListItem>Üç</asp:ListItem>
            <asp:ListItem>Dört</asp:ListItem>
        </asp:CheckBoxList>
        <asp:CustomValidator ID="cfvClientKinds" runat="server" Display="Dynamic" CssClass="label label-danger" ErrorMessage="CustomValidator" OnServerValidate="cfvClientKinds_ServerValidate"></asp:CustomValidator>
        <br />
        <asp:LinkButton ID="UpdateButton" runat="server" CausesValidation="True" CommandName="Update" Text="Update" />
        &nbsp;<asp:LinkButton ID="UpdateCancelButton" runat="server" CausesValidation="False" CommandName="Cancel" Text="Cancel" />
    </EditItemTemplate>
</asp:FormView>

And codebehind with your code:

protected void cfvClientKinds_ServerValidate(object aSource, ServerValidateEventArgs aArgs)
        {
            CustomValidator cvCheckBoxKinds = aSource as CustomValidator;
            CheckBoxList cblClientClassifications = (CheckBoxList)FormView1.FindControl("cblClientClassifications");
            int checkedCount = 0;
            if (cvCheckBoxKinds != null)
            {
                foreach (ListItem listItem in cblClientClassifications.Items)
                {
                    if (listItem.Selected)
                    {
                        checkedCount++;
                    }
                }

                if (checkedCount == 0)
                {
                    aArgs.IsValid = false;
                    cvCheckBoxKinds.ErrorMessage = "Select client kind.";
                }
            }
        }

I Ali Shahrokhi's method is shorter and works as well as yours..

protected void cfvClientKinds_ServerValidate(object aSource, ServerValidateEventArgs aArgs)
        {
            CustomValidator cvCheckBoxKinds = aSource as CustomValidator;
            CheckBoxList cblClientClassifications = (CheckBoxList)FormView1.FindControl("cblClientClassifications");
            aArgs.IsValid = cblClientClassifications.SelectedItem != null;
            cvCheckBoxKinds.ErrorMessage = "Select client kind.";
        }

if you check as you entered edititemtemplate in formview you'll see before submitting that your customvalidators span will be there just as you mentioned that's because server hasn't sent it to the client yet somehow.