David Findley's Blog

My little home in the cloud.

  • Certificate error with Web Platform Installer

     A friend of mine was having an issue getting the Web Platform Installer to work on his Windows Server 2008 R2 box. He said there was some sort of cert error and asked me to try https://go.microsoft.com/fwlink/?LinkId=158722 on my local machine to see if I got the cert error.  I tried it and I did get a cert error on Windows 7 64bit. I happened to notice that that url simply redirects to https://www.microsoft.com/web/webpi/2.0/WebProductList.xml . Out of curiosity I dropped to a command line and tried to run .\WebPlatformInstaller.exe /? to see if there were any command line options. It gave an error that said invalid URI. So we tried running it with the product list url like: "WebPlatformInstaller.exe https://www.microsoft.com/web/webpi/2.0/WebProductList.xml" . This seems to get around the expired cert that is on go.microsoft.com.

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  • ASP.NET MVC ModelState should work like TempData

    I prefer to have the actions that forms post to just process the posted data and then redirect to a different action for viewing the results. So in order to pass validation errors back to the form action I need ModelState to work like TempData does. In fact it seemed that before ModelState was added that one of the most common scenarios for using TempData was passing validation error messages between actions so I’m not sure why it doesn't already work like this. I’m using RC2 so its doubtful this will change before RTM. :(

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  • Merry Christmas Indeed!

    Janice went all out this year and got me an Ibanez JS1000 (Joe Satriani series) guitar, a Line 6 POD X3 Live effects board and a pair of Roland CM-30 amplified monitors. My fingers are all tore up now since I've been out of practice for some time now. But it sure is fun to get back to some jamming. The JS1000 is pretty light and has easy action. Combined with the POD X3 I can get quite a variety of amazing sounds. I even got the X3 hooked up to my MacBook Pro and finally was able to try out Garage Band. I was able to lay down the rhythm track for Crushing Day (what I could remember from back in the day) and then play the lead part over it with no lag. The roland CM-30s are nice because I can run my Alesis QS8 and the POD X3 into them at the same time. This is probly the best setup I've ever had.

    Later today I hooked up a microphone to the X3 and the kids had a blast talking and play singing into it. "Daddy it sounds kinda like I'm in a cave...". Perhaps I should cut down some of that reverb. :) 

    Santa Clause was good to me this year. (Thanks Janice)

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  • LINQ - The Uber FindControl

    With a simple extension method to ControlCollection to flatten the control tree you can use LINQ to query the control tree:

    public static class PageExtensions
    {
        public static IEnumerable<Control> All(this ControlCollection controls)
        {
            foreach (Control control in controls)
            {
                foreach (Control grandChild in control.Controls.All())
                    yield return grandChild;
    
                yield return control;
            }
        }
    }
    
    Now I can do things like this:
    // get the first empty textbox
    TextBox firstEmpty = accountDetails.Controls
        .All()
        .OfType<TextBox>()
        .Where(tb => tb.Text.Trim().Length == 0)
        .FirstOrDefault();
    
    // and focus it
    if (firstEmpty != null)
        firstEmpty.Focus();
    

    Pretty cool! I can do all sorts of querying of the control tree now. LINQ you are my hero.

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  • A Quick Fix for the Validator SetFocusOnError Bug

    The ASP.NET validators have this nice property called "SetFocusOnError" that is supposed to set the focus to the first control that failed validation. This all works great until your validator control is inside a naming container. I ran into this recently when using validators in a DetailsView. Take this simple example:
    <%@ Page Language="C#" %>
    <script runat="server">
        protected void Page_Load(object sender, EventArgs e)
        {
            if (!IsPostBack)
                DataBind();
        }
    </script>
    <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
    <html xmlns="http://www.w3.org/1999/xhtml">
    <head runat="server">
        <title></title>
    </head>
    <body>
    <form id="_frm" runat="server">
        <asp:DetailsView 
            ID="dv1" 
            DefaultMode="Edit" 
            DataSource='<%# new object[1] %>' 
            runat="server"
        >
        <Fields>
            <asp:TemplateField HeaderText="First Name:">
                <EditItemTemplate>
                    <asp:TextBox ID="FirstNameTextBox" runat="server" />
                    <asp:RequiredFieldValidator 
                        ID="FirstNameValidator1"
                        ControlToValidate="FirstNameTextBox"
                        ErrorMessage="First name is required."
                        Display="Dynamic"
                        EnableClientScript="false"
                        SetFocusOnError="true"
                        ValidationGroup="bug"
                        Text="*"
                        runat="server" 
                    />
                </EditItemTemplate>
            </asp:TemplateField>
        </Fields>
        <FooterTemplate>
            <asp:ValidationSummary 
                ID="vs1"
                DisplayMode="List"
                ValidationGroup="bug"
                runat="server" 
            />
            <asp:Button 
                ID="Button1" 
                Text="Post Back"
                ValidationGroup="bug" 
                runat="server" 
            />
        </FooterTemplate>
        </asp:DetailsView>
    </form>
    </body>
    </html>
    If you run this page and do a view source you'll see that the FirstNameTextBox gets rendered like this:
    <input name="dv1$FirstNameTextBox" type="text" id="dv1_FirstNameTextBox" />
    If you just do a post back without entering a value to cause the validator to fail it will output this line of java script in an attempt to set the focus to the invalid element:
    WebForm_AutoFocus('FirstNameTextBox');
    See anything wrong with this? It would seem that the validators just use the string value you typed in for the ControlToValidate property rather than doing a FindControl and using the UniqueID. This is exactly what happens and I verified it with reflector. The Validate method on BaseValidator does this:
    if ((!this.IsValid && (this.Page != null)) && this.SetFocusOnError)
    {
      this.Page.SetValidatorInvalidControlFocus(this.ControlToValidate);
    }
    If you follow the call to SetValidatorInvalidControlFocus you'll see that it never resolves the full UniqueID of the control that its going to set focus to.
     
    Ok, so this sucks. How do I work around it. My solution was to simply ditch using the SetFocusOnError property and implement the focus logic myself which is actually pretty easy. I overrode Validate method on my Page like this:
    public override void Validate(string group)
    {
        base.Validate(group);
    
        // find the first validator that failed
        foreach (IValidator validator in GetValidators(group))
        {
            if (validator is BaseValidator && !validator.IsValid)
            {
                BaseValidator bv = (BaseValidator)validator;
                
                // look up the control that failed validation
                Control target = 
                    bv.NamingContainer.FindControl(bv.ControlToValidate);
                
                // set the focus to it
                if (target != null)
                    target.Focus();
                
                break;
            }
        }
    }
    If your using C# 3 this is even easier using LINQ:
    public override void Validate(string group)
    {
        base.Validate(group);
    
        // get the first validator that failed
        var validator = GetValidators(group)
            .OfType<BaseValidator>()
            .FirstOrDefault(v => !v.IsValid);
    
        // set the focus to the control
        // that the validator targets
        if (validator != null)
        {
            Control target = validator
                .NamingContainer
                .FindControl(validator.ControlToValidate);
    
            if (target != null)
                target.Focus();
        }
    }
    
    I hope this saves someone the headache of tracking this down.

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  • A VS.NET Macro to Generate Machine Keys.

    I needed to create a new machine key for an asp.net site. I found a couple of command line utils out on the web that would create a new key but I thought it would be easier to just have it avail in VS.NET. So, I threw together this little macro that will generate the machine key and insert it. Just run the macro while you have you web.config open in VS.NET. If you already have a machinekey it will find it and replace it. If not it will just add it right after the <system.web> node. It should do the proper indents and everything too.

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