Custom Validator

daveharney · #1 (**permalink**) January 14th, 2014, 04:57 PM

Hi Imar,

I've been trying to get a Custom Validator to work in a Listview. I've been using your advice starting on page 327. The server side is fine and I'm able to get into the client JS but I'm not able to access the data field that is being validated.

I set up a small website and a stripped down listview just to test this out with a trivial validation test. I've tried everything you wrote about and lots of time on stack overflow. My web.config has "<add key="ValidationSettings:UnobtrusiveValidationMode" value="WebForms"/>". I did change the Global.asax file per your suggestion and added the scriptmanager code but that didn't seem to help either. So, I've back out the scriptmanager for now. I'm including all the code for the aspx and vb:

aspx

Code:

<%@ Page Language="VB" AutoEventWireup="false" CodeFile="Default.aspx.vb" Inherits="_Default" %>
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title></title>
    <script type="text/javascript" src="http://code.jquery.com/jquery-2.0.3.min.js"></script>
    <script type="text/javascript">
        function checklength(source, args) {
            // this function does fire but can't get at the field
            //alert("in js")
            //if (SecondField != '') {
            //    args.IsValid = true;
            //}
            //else {
            //    args.IsValid = false;
            //}
        }
    </script>
</head>
<body>
    <form id="form1" runat="server">
        <div>                                  
            <asp:ListView ID="ListView1" runat="server" DataKeyNames="myKey"
                itemtype="TestTable"
                selectmethod="ListView1_GetData"
                updatemethod="ListView1_UpdateItem" >
                <EditItemTemplate>
                    <tr style="">
                        <td>
                            <asp:Button ID="UpdateButton" runat="server" CommandName="Update" Text="Update" />
                            <asp:Button ID="CancelButton" runat="server" CommandName="Cancel" Text="Cancel" />
                        </td>
                        <td>
                            <asp:Label ID="myKeyLabel1" runat="server" Text='<%# Eval("myKey") %>' />
                        </td>
                        <td>
                            <asp:TextBox ID="FirstFieldTextBox" runat="server" Text='<%# Bind("FirstField") %>' />
                        </td>
                        <td>
                            <asp:TextBox ID="SecondFieldTextBox" runat="server" Text='<%# Bind("SecondField") %>' ClientIDMode="Static"  />
                        </td>
                        <td>
                            <asp:TextBox ID="commentTextBox" runat="server" Text='<%# Bind("comment") %>' />
                        </td>
                    </tr>
                    <tr>
                        <td></td><td></td>
                        <td>
            <asp:CustomValidator ID="CustomValidator1" runat="server" 
                ErrorMessage="xx not allowed" 
                ControlToValidate="SecondFieldTextBox" 
                Display="Dynamic" 
                ClientValidationFunction="checklength"
                OnServerValidate="CustomValidator1_ServerValidate" >
            </asp:CustomValidator>                  
                        </td>
                    </tr>
                </EditItemTemplate>
                <EmptyDataTemplate>
                    <table runat="server" style="">
                        <tr>
                            <td>No data was returned.</td>
                        </tr>
                    </table>
                </EmptyDataTemplate>
                <ItemTemplate>
                    <tr style="">
                        <td>
                            <asp:Button ID="EditButton" runat="server" CommandName="Edit" Text="Edit" />
                        </td>
                        <td>
                            <asp:Label ID="myKeyLabel" runat="server" Text='<%# Eval("myKey") %>' />
                        </td>
                        <td>
                            <asp:Label ID="FirstFieldLabel" runat="server" Text='<%# Eval("FirstField") %>' />
                        </td>
                        <td>
                            <asp:Label ID="SecondFieldLabel" runat="server" Text='<%# Eval("SecondField") %>' />
                        </td>
                        <td>
                            <asp:Label ID="commentLabel" runat="server" Text='<%# Eval("comment") %>' />
                        </td>
                    </tr>
                </ItemTemplate>
                <LayoutTemplate>
                    <table runat="server">
                        <tr runat="server">
                            <td runat="server">
                                <table id="itemPlaceholderContainer" runat="server" border="0" style="">
                                    <tr runat="server" style="">
                                        <th runat="server"></th>
                                        <th runat="server">myKey</th>
                                        <th runat="server">FirstField</th>
                                        <th runat="server">SecondField</th>
                                        <th runat="server">comment</th>
                                    </tr>
                                    <tr id="itemPlaceholder" runat="server">
                                    </tr>
                                </table>
                            </td>
                        </tr>
                        <tr runat="server">
                            <td runat="server" style=""></td>
                        </tr>
                    </table>
                </LayoutTemplate>
            </asp:ListView>
            </div>
        <div>
            <asp:label id="msglabel"  runat="server"  Text=""></asp:label>
        </div>
    </form>
</body>
</html>

VB (validator code from stackoverflow)

Code:

Imports TinyDBEntities
Imports System.Data
Imports System.Linq
Partial Class _Default
    Inherits System.Web.UI.Page
    Public Function ListView1_GetData() As IQueryable(Of TestTable)
        Dim myContext As New TinyDBEntities()
        Return From mydata In myContext.TestTables Select mydata
    End Function
    Public Sub ListView1_UpdateItem(testtable As TestTable)
        If Page.IsValid Then
        Else
            msglabel.Text = " Your update Failed"
            Exit Sub
        End If
        Dim myContext As New TinyDBEntities()
        Dim item As TestTable = (From s In myContext.TestTables
                         Where s.myKey = testtable.myKey
                         Select s).SingleOrDefault()
        If item Is Nothing Then
            msglabel.Text = " Your update Failed"
            Return
        End If
        TryUpdateModel(item)
        item.FirstField = Convert.ToInt32(testtable.FirstField)
        If ModelState.IsValid Then
            myContext.SaveChanges()
            msglabel.Text = " Your update was Successful"
        Else
            msglabel.Text = " Your update Failed"
        End If
    End Sub

    Protected Sub CustomValidator1_ServerValidate(source As Object, ByVal args As System.Web.UI.WebControls.ServerValidateEventArgs)
        Dim cv As CustomValidator = CType(source, CustomValidator)
        Dim testpos As Integer
        Dim test As String
        test = args.Value
        testpos = InStr(1, test, "xx")
        If testpos > 0 Then
            args.IsValid = False
            cv.ErrorMessage = "xx is not allowed"
        Else
            args.IsValid = True
        End If
        'MsgBox(args.Value)
    End Sub
End Class

So, the problem is that if I want to warn the user at client time, I just can't seem to get at the data field. I've tried to also use the name as shown in the browser source code.

Thanks.

Imar · #2 (**permalink**) January 14th, 2014, 05:08 PM

Hi there,

First of all, I think your field is called SecondFieldTextBox, and not SecondField as you use in the JavaScript function.

But more importantly, since this code is in a list, there is not a single SecondFieldTextBox, there are multiple which means you won't be able to write the JavaScript function to target a single control.

You want to look at args.Value instead, as that provides you with the value for the control that fired the validation function. For more information, check http://msdn.microsoft.com/en-us/libr...vs.110%29.aspx

Hope this helps,

Imar

daveharney · #3 (**permalink**) January 14th, 2014, 06:58 PM

Quote:

SecondFieldTextBox, Imar

Yes, I tried all variations of that name. But, as you suggest, that approach is going to be ambiguous.

Quote:

You want to look at args.Value instead, as that provides you with the value for the control that fired the validation function.
Imar

Yes, you are right as usual! I should have thought of that because args.value is used on the server side - but, important to use "Value" and not "value" just as you showed.

So, this works:

Code:

       function checklength(source, args) {
          var str = args.Value
            var n = str.indexOf("xx");
            if (n == -1) {
                args.IsValid = true;
            }
            else {
                args.IsValid = false;
                alert ("no xx allowed")
            }
        }

I still have some fooling around to do with completely understanding the flow of control with both client and server code - but, this was the big show stopper.

Thanks once again. BTW, I read a comment where MS plans to reinstate the EF model they had in EF5. Is this true?

Imar · #4 (**permalink**) January 14th, 2014, 08:40 PM

Just in case it helps, here's what happens:

1. The page loads
2. You fill in some values
3. You hit the submit button
4. The client side code fires, and validates the fields. When at least one of them doesn't pass validation, one or more error messages are shown and the form is *not* submitted.
5. You complete the form and hit submit again.
6. On the server, the validators run again. Since the form is validated already at the client, they should pass without further validation.

However, if you disable client side scripts (a malicious user could do that easily), step 4 is skipped, and step 6 will still catch any incorrect entries at the server. That's why server-side validation is so important.

Hope this helps.

>> BTW, I read a comment where MS plans to reinstate the EF model they had in EF5. Is this true?

Not sure I understand what you mean with this.

Cheers,

Imar

daveharney · #5 (**permalink**) January 14th, 2014, 09:06 PM

Hi Imar,

Thanks for the flow explanation - yes, that helps.

Re EF:

"We are planning to have a preview of a version of the EntityDataSource that works with EF6 out soon. I will update this thread when it is available."

This is at or near the bottom of this thread where I was venting a bit about lack of doc for VB-linq-EF6 in VS2013:
https://entityframework.codeplex.com/discussions/434936

"divega" posted this on what looks like 12-21-13. I've not heard anything since.

Imar · #6 (**permalink**) January 15th, 2014, 08:31 AM

Oh, I see. Yes, I read that elsewhere too. But in general it seems Microsoft is recommending against using this control now. They update it primarily for Dynamic Data Sites. The preferred solution is to use Model Binding which I am covering in my upcoming ASP.NET 4.5.1 / VS 2013 book.

Cheers,

Imar

daveharney · #7 (**permalink**) January 15th, 2014, 10:28 AM

Hi Imar,

Yes, I also like the Model Binding methods. My big complaint with Microsoft has been the lack of documentation for EF6-Linq-VB - especially for using controls like Listview. We need your new book! I got a notice from Amazon saying "delivery estimate: March 19, 2014".

BTW, I've launched a companion site for doing a survey of bicyclists using my main site. Also some changes to the main one. Although most of the difficult changes are in the admin area and not visible, there are a few worth looking at. The "Why Ozaukee " page has a slide show using code from a fellow in Russia and the "Routes" page has been overhauled plus some cute jquery. The survey site uses a template from a UK guy (note: I gave you a mention on the Contact Us page). Getting to be an international effort.

Main site: bikex (which also has a link to the survey)
Survey: survey