- Introduction
- Implementing a Suitable Data Source
- What Is a DataList Server Control?
- Binding to the DataList
- Summary
Like this article? We recommend
Like this article? We recommend
Like this article? We recommend
Implementing a Suitable Data Source
Many articles and books demonstrate how to connect to traditional data sources, such as a table in a database. What may not be obvious is that any object that implements the IEnumerable or IListSource interface can also be used as a data source. The benefit is that you can bind custom objects directly to web pages. For example, you could bind an array of contacts directly to a web page. There is no requirement that you have to use a DataSet.
Since you won't have much trouble finding code that demonstrates binding to a DataSet, we'll take a different approach by binding to a class that doesn't contain a DataSet or DataTable. The two classes we'll define are a Contact class that contains fields describing contact information and a Contacts class that contains an ArrayList of Contact objects.
The Contact class contains First Name, Last Name, Email, and URL properties. The Contacts class contains an ArrayList property. The ArrayList class implements the IEnumerable interface and will consequently let us bind to the DataList web control. Listing 1 shows the Contact and Contacts classes:
Listing 1—Contact Information Classes
Option Explicit On
Option Strict On
Public Class Contact
Private FFirstName As String
Private FLastName As String
Private FEMail As String
Private FURL As String
Public Property FirstName() As String
Get
Return FFirstName
End Get
Set(ByVal Value As String)
FFirstName = Value
End Set
End Property
Public Property LastName() As String
Get
Return FLastName
End Get
Set(ByVal Value As String)
FLastName = Value
End Set
End Property
Public Property EMail() As String
Get
Return FEMail
End Get
Set(ByVal Value As String)
FEMail = Value
End Set
End Property
Public Property URL() As String
Get
Return FURL
End Get
Set(ByVal Value As String)
FURL = Value
End Set
End Property
Public ReadOnly Property FullName() As String
Get
Return String.Format("{0}, {1}", _
FLastName, FFirstName)
End Get
End Property
End Class
Public Class Contacts
Private FItems As ArrayList
Public ReadOnly Property Items() As ArrayList
Get
Return FItems
End Get
End Property
Public Sub New()
FItems = New ArrayList()
End Sub
End Class
The two classes are self-explanatory, so I won't go into detail. The ArrayList in the Contacts class, as mentioned, implements the IEnumerable interface. The IEnumerable interface has one method, GetEnumerator. GetEnumerator returns an instance of an object that implements the IEnumerator interface. The IEnumerator interface has three members: MoveNext, Reset, and Current. Enumerators, an example of the iterator pattern, supports iterating over all of the elements in a collection. This general ability of Enumerators allows instances of classes such as DataTable and our Contacts class to be bound to the DataList web control.