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Book Excerpt: Working with the DataList Control
In this chapter, we will cover the ASP.NET DataList control. We will learn about
the following:
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This chapter excerpt from
ASP.NET Data Presentation Controls Essentials by Joydip Kanjilal,
is printed with permission from Packt Publishing,
Copyright 2007.
The ASP.NET DataList Control
The DataList control like the Repeater control is a template driven, light
weight control, and acts as a container of repeated data items. The templates
in this control are used to defi ne the data that it will contain. It is
flexible in the sense that you can easily customize the display of one or more
records that are displayed in the control. You have a property in the DataList
control called RepeatDirection that can be used to customize the layout of the
control.
The RepeatDirection property can accept one of two values, that is, Vertical or
Horizontal. The RepeatDirection is Vertical by default. However, if you change
it to Horizontal, rather than displaying the data as rows and columns, the
DataList control will display them as a list of records with the columns in the
data rendered displayed as rows.
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This comes in handy, especially in situations where you have too many columns in
your database table or columns with larger widths of data. As an example,
imagine what would happen if there is a fi eld called Address in our Employee
table having data of large size and you are displaying the data using a
Repeater, a DataGrid, or a GridView control. You will not be able to display
columns of such large data sizes with any of these controls as the display
would look awkward. This is where the DataList control fits in.
In a sense, you can think the DataList control as a combination of the DataGrid
and the Repeater controls. You can use templates with it much as you did with a
Repeater control and you can also edit the records displayed in the control,
much like the DataGrid control of ASP.NET. The next section compares the
features of the three controls that we have mentioned so far, that is, the
Repeater, the DataList, and the DataGrid control of ASP.NET.
When the web page is in execution with the data bound to it using the Page_Load
event, the data in the DataList control is rendered as DataListItem objects,
that is, each item displayed is actually a DataListItem. Similar to the
Repeater control, the DataList control does not have Paging and Sorting
functionalities built into it.
Using the DataList Control
To use this control, drag and drop the control in the design view of the web
form onto a web form from the toolbox.
Refer to the following screenshot, which displays a DataList control on a web
form:
The following list outlines the steps that you can follow to add a DataList
control in a web page and make it working:
1. Drag and drop a DataList control in the web form from the toolbox.
2. Set the DataSourceID property of the control to the data source that you
will use to bind data to the control, that is,
you can set this to an SQL Data Source control.
3. Open the .aspx fi le, declare the
element and defi ne the fi
elds as per your requirements.
4. Use data binding syntax through the Eval() method to display data in
these defi ned fi elds of the control.
You can bind data to the DataList control in two different ways, that is, using
the DataSourceID and the DataSource properties. You can use the inbuilt
features like selecting and updating data when using the DataSourceID property.
Note that you need to write custom code for selecting and updating data to any
data source that implements the ICollection and IEnumerable data sources. We
will discuss more on this later. The next section discusses how you can handle
the events in the DataList control.
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