I have a website that is supposed to display pictures. The name of the picture files is stored in a database called pictures (duh).

The table goes like this:

id: 1
name: landscape.jpg
width: 300
height: 300
description: A picture of a mountain.

The problem is that sometimes I want width and height to be null, and using the Datalist control that can be a problem, for the Datalist control puts "" whenever there's a null value. Take a look at the code below:

<asp: DataList id="datalist1" border=0 RepeatDirection="Horizontal" RepeatColumns="3" runat="server">
<ItemTemplate>
<table>
<tr>
<td><img src="images/<%# DataBinder.Eval(Container.DataItem,"name") %>" width="<%# DataBinder.Eval(Container.DataItem,"width") %>" /></td>
</tr>
</table>
</ItemTemplate>
</asp: DataList>

The problem is right here:
"<%# DataBinder.Eval(Container.DataItem,"width") %>"

Can I make Datalist ignore the width when it is nul, or at least print out some other valuel? Or do I have to program everything using a DataReader and arrays, as if it was PHP?

__________________________________________________ ______________
http://www.carbotek.org

You could change your SQL Query to select ... IsNull(width, 0), IsNull(height, 0) to avoid seeing null values in your .NET code. Otherwise, you would need to use a different coding style and fill your stuff in using code-behind, like C# or VB.

You can iterate a DataReader ( while(dr.Read()) ), and then use if(!dr.IsDbNull("width")) Response.Write("<img ..."); to output code directly, or add it to the text property of a server-side page control.

I thought of a datareader too. That's how I'd do it with PHP, which lacks DataGrids and Repeaters.

Here is a solution:

sqlstr = "SELECT ids, name, ISNULL(width,300) as width, height, description FROM pictures ";
SqlDataAdapter MyAdapter = new SqlDataAdapter();
MyAdapter.SelectCommand = new SqlCommand(sqlstr, conPubs);

Look at the first line:
I am telling SQL to replace any null value in width with 300. That's because I intent to give every picture a width value, but not a height value. Browsers will automatically give a value to the height according to the picture's dimensions, so all I need is a width.

The rest looks like jargon but works. Take a look at the line that begins with
<%# ((Convert.IsDBNull ... I am telling ASP.NET to give the picture a height value only if the value in the database is not null. I could've done this in the SQL instruction, but I decided to do it inside the Datalist.

<asp: DataList id="datalist1" border=0 RepeatDirection="Horizontal" RepeatColumns="3" runat="server">
<ItemTemplate>

<img src="http://www.webmaster-talk.com/images/<%# DataBinder.Eval(Container.DataItem,"name")%>"
width = "<%#DataBinder.Eval(Container.DataItem, "width")%>"

<%# ((Convert.IsDBNull(DataBinder.Eval(Container.DataI tem, "height"))) ? "" : "height = " + DataBinder.Eval(Container.DataItem, "height")) %>

alt="<%# DataBinder.Eval(Container.DataItem,"description")% >" />



</ItemTemplate>

</asp: DataList>

It works, but the script looks complicated. I wonder if there's an easier way to do it.

__________________________________________________ ___________

http://www.carbotek.org

An easier way to do it - at least slightly - would be to save the SQL code into the database as a view. This is an example of why people use them; to hide the structure of the underlying data from an application.

Although you might be better off filling in the null values with 300 ( or the actual value ) and then disallowing nulls in that column.