I just came across a form that stopped me pasting into it.  Rather annoying, but could be useful if you really want to force users to do this.

Easily done.  Just add  onpaste=”return false” inside the <input> tag.

I’m moving an existing project over piece-by-piece. As I come across stumbling blocks I’m adding them to this post.

Code formatting

There isn’t the automatic formatting of code that you get with VB.NET in Visual Studio

Correct us of ToString

Error: Cannot convert method group ‘ToString’ to non-delegate type ‘string’. Did you intend to invoke the method?
When using the following code:

Regex.Replace(Regex.Replace(aString, aRegexPattern, "-"), "-{2,}", "-").ToString;

Cause:
.ToString without brackets is a property, I needed to call

.ToString()

No optional parameters on methods

You have to overload the method instead

Passing char into a method

Error: The best overloaded method match for ‘string.PadLeft(int, char)’ has some invalid arguments

Using:

aDate.Day.ToString().PadLeft(2, "0")

For some reason the char in the PadLeft needs to be wrapped in single quotes not double.

Fix:

aDate.Day.ToString().PadLeft(2, '0')

Parameters need to be exact

It’s a lot more picky about the types you pass into methods
In VB.NET I was getting away with passing a Double into Rectangle initialiser that actually wanted an int.

double outputHeight = 0;
double outputWidth = 0;

Rectangle rec = new Rectangle(0, 0, outputWidth, outputHeight);

Gives the error: The best overloaded method match for ‘System.Drawing.Rectangle.Rectangle(int, int, int, int)’ has some invalid arguments

Fixed with:

Rectangle rec = new Rectangle(0, 0, (int)outputWidth, (int)outputHeight);

Dividing 2 integers

Dividing 2 integers in VB.NET returns a Double.
But in C# the following returns zero:

int imageHeight = 768;
int imageWidth = 1024;
outputHeight =  imageHeight / imageWidth;

This works:

outputHeight =  (Double) imageHeight / (Double) imageWidth;

Saving a Bitmap

I was ensuring the Bitmap was saved with 100% quality like:

System.Drawing.Imaging.EncoderParameter qualityParam = new System.Drawing.Imaging.EncoderParameter(System.Drawing.Imaging.Encoder.Quality,100);

I was getting an error “Parameter is not valid”. Finally traced it to the 100 parameter C# wanted it explicitly typed, using 100L

System.Drawing.Imaging.EncoderParameter qualityParam = new System.Drawing.Imaging.EncoderParameter(System.Drawing.Imaging.Encoder.Quality,
<strong>100L</strong>);

Container.DataItem

<%#Container.DataItem["value"]%>

Gives the error: Cannot apply indexing with [] to an expression of type ‘object’

Fixed by changing to:

<# DataBinder.Eval(Container.DataItem, "value") %>

Case sensitivity!

Not working:

<%# container.findcontrol("filePhoto").clientid()%>

Working (Notice capital C, I and D in ClientID):

<%# Container.FindControl("filePhoto").ClientID%>

Request.QueryString

You need to change Request.QueryString(“carid”) to Request.QueryString["carid"]

Accessing a field in a DataRow

Using

hypSubSection.Text = drCar("car");

Gives the following error “‘drCar’ is a ‘variable’ but is used like a ‘method’”

It needs to be:

hypSubSection.Text = drCar["car"].ToString();

Raising events

Nice and easy in VB.NET
Declare the event:

Public Event cropped(ByVal aString As string)

Raise the event

RaiseEvent cropped("something")

In C# you need

    //declaring the event handler delegate
    public delegate void CropEventHandler(string aString);
    //declaring the event
    public event CropEventHandler cropped;

Then raise it with

     if (cropped != null)
        {
            cropped(paramsToPassBack);
        }

Debugging this cropped was always null. This turned out to be because nothing was listening to the event!
This doesn’t seem right to me, as the point of using a delegate is go make the object raising the event independent to any objects listening for the event.

javascript:void(prompt('',gApplication.getMap().getCenter()));

I’ve added this as a bookmarklet for ease of use.

To do the same drag this into your browser toolbar Google Map Centre

A very easy way to stop this happening is to override the window.scroll function.
Add the following to the page with the form on.

<script type="text/javascript">
     window.scrollTo = function( x,y ) {
        return true;
    }
</script>

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.