This is because the html that is rendered is a textarea instead on a regular input field.

Customvalidator to the rescue!

For example:

 <asp:TextBox runat="server" ID="txtIntro" TextMode="MultiLine" Rows="3" />
 <asp:CustomValidator runat="server" ID="cvIntro" maxlength="255"
	ErrorMessage="Please enter 255 characters or less"
	ControlToValidate="txtIntro"
	ClientValidationFunction="checkTextAreaLength" />

This “fires” this clientside function:

<script type="text/javascript">
    function checkTextAreaLength(source, arguments) {
        var maxlength = $(source).attr("maxlength");
        if (maxlength == undefined) maxlength = 255;
        if (arguments.Value.length > maxlength)
            arguments.IsValid = false;
        else
            arguments.IsValid = true;
    }

</script>

One thing to note is that I’ve had to add the maxlength attribute to the customvalidator not to the textbox.  I would prefer to have maxlength set on the textbox but so far I’ve been unable to work this out.  If anyone has any ideas please let me know.

e.g.

<label for="emailaddress">Email</label>
<input type="text" id="emailaddress"/>

Now if you’re referencing asp.net controls you can use the clientid property.

e.g.

<label for="<%= emailaddress.clientid()%>">Email</label>
<asp:TextBox runat="server" ID="emailaddress" />

All nice an easy so far. The situation gets a little bit more complicated when you start nesting this inside a repeater.

e.g.

<asp:Repeater runat="server" ID="rpt1">
<itemTemplate>

<label for="<%= emailaddress.clientid()%>">Email</label>
<asp:TextBox runat="server" ID="emailaddress" />

</itemTemplate>
</asp:Repeater>

this won’t work.
Here’s what you need to do instead.

<asp:Repeater runat="server" ID="rpt1">
<itemTemplate>

<label for="<%# container.findcontrol("emailaddress").clientid()%>">Email</label>
<asp:TextBox runat="server" ID="emailaddress" />

</itemTemplate>
</asp:Repeater>

Here’s somewhere I’ve implemented 1 of the techniques.

The task: return records for this month.

Usually I’d write something like

select * from results where month(dateadded) = month(now()) and year(dateadded) = year(now())

The problem with this is that 2 functions (month() and year()) need to be applied to every row to filter the results, this obviously requires overhead.  Also we’re missing out on any indexes that might be on the dateadded field.

A better approach is to use

select * from results where dateadded >= DATE_FORMAT(now() ,'%Y-%m-01')

With this approach 1 function is run to find the first day of the month, and if the dateadded field is indexed we’ll benefit from this.

Anyway here’s how I go about loading csv data into MySql

• Prepare your data in a program such as excel or open office
• Save as comma delimied or tab delimited in the file system where mysql stores the data, e.g. if the data is to go in a database called “test” then save the csv in C:\Program Files\MySQL\MySQL Server 5.0\data\test
• Create a temporary import table whose structure matches the file to import
• Make each field a varchar(255) even if the field contains numbers, we can always remove rogue data later – let’s just get it into the database first!
• Load in the data (note: this is ignoring the first line as it contains the column headers and is set for a tab delimited file)

LOAD DATA INFILE 'myimport.txt' INTO TABLE test.tempimporttable

FIELDS TERMINATED BY '\t'

LINES TERMINATED BY '\r\n'

IGNORE 1 LINES

As an asp.net developer and jQuery advocate I know I’m going to find this tip very useful

http://devoma.com/post/JQuery-and-ASPNET-validators.aspx

Dim KeyphraseNode As XmlNode = xmlDoc.SelectSingleNode( _

String.Format("/websites/website[@url='{0}']/keyphrases/keyphrase[@value='{1}' and @type='{2}']" , _

WebsiteUrl, keyphrase.ToLower, keyphraseType))

Unfortunately users were testing for values with different capitalisations so the program was reporting that the nodes didn’t exist when actually they did.

I could have change the data in the xml file so that all data was stored as lowercase, but that would be nasty.

After a bit of digging round and consulting my trusty xpath book I found that there isn’t a nice and easy lowercase function built into xpath.  And the best approach is to use the translate function.  So the solution turned out to be

Dim KeyphraseNode As XmlNode = xmlDoc.SelectSingleNode( _

String.Format("/websites/website[@url='{0}']/keyphrases/keyphrase[translate(@value,

'ABCDEFGHIJKLMNOPQRSTUVWXYZ', 'abcdefghijklmnopqrstuvwxyz')='{1}' and @type='{2}']", _

WebsiteUrl, keyphrase.ToLower, keyphraseType))

Hope that helps if anyone else needs to do a case insensitive xpath search.

It’s best practice to turn off viewstate for the whole page or for individual usercontrols if they don’t require viewstate.  The deciding factor here is: does the page or usercontrol perform postbacks.

Even with careful pruning of viewstate you’ll probably find your viewstate is still large…

What you can do

Now there are a couple of strategies I’ve seen for working round this, both involve overriding the page

1 is to intercept the page rendering and move the viewstate hidden variable to the bottom of the page.

Here’s an example http://www.dotnetdiary.com/labels/Moving%20ViewState%20Field.html

2 is a very clever solution that keeps the viewstate information on the server and justs passes a key back and forth to the client.

I read about this approach here http://www.eggheadcafe.com/articles/20040613.asp

Here’s my approach

Now since I don’t think that viewstate bloat has too much of an impact on page performance for real users I’m only going to worry about search engine spiders.

asp.net has a way of detecting spiders – now I’m not saying it’s going to be 100% accurate but in my tests it’s been accurate enough for this technique.

In the page load of your page (or master page)

If Request.Browser.Crawler Then Page.EnableViewState = False

er that’s it, pretty simply eh?

You can verify if this is working by viewing the source of the cached version of the page that google holds.

Hope that helps!

My button (server-side) was pumping out a bit of javascript 

Page.ClientScript.RegisterStartupScript(GetType(String),
         "loginunsuccessful", "<script type=""text/javascript"">
         alert('Login unsuccessful – please try again');</script>")

And this kept causing the error.

I tried using the prescribed fix: ClientScript.RegisterForEventValidation(mycontrol.uniqueid) in the prerender.  Still got the error.

Here’s how I fixed it.  RegisterStartupScript does the job of running at startup by emiting the js right at the foot of the page.  I wrapped my JS in jQuery’s own onload code.

Page.ClientScript. RegisterStartupScript(GetType(String),
          "loginunsuccessful", "<script type=""text/javascript"">
          $(document).ready(function(){alert('Login unsuccessful – please try again');});
          </script>")

Still the same error, I then changed to using Page.ClientScript.RegisterClientScriptBlock, which emits the JS in the midst of the html and hey presto no errors.  This is without using the RegisterForEventValidation I’d like to add.

Final code:

Page.ClientScript.RegisterClientScriptBlock(GetType(String),
          "loginunsuccessful", "<script type=""text/javascript"">
          $(document).ready(function(){BlockAlert('Login unsuccessful – please try again');});
          </script>")

Simple to fix when you know how.

After a big of digging I found how to use jQuery to “catch” the unload event. In case anyone else needs it:

$(window).unload( function () { GUnload(); } );

In your ashx change

Public Class yourclass :     Implements IHttpHandler

    Implements SessionState.IRequiresSessionStat

to

Public Class yourclass

Implements IHttpHandler

    Implements SessionState.IRequiresSessionStat