Binding ObjectDataSource controls to Custom Methods

There are a few ways to bind the ObjectDataSource control to your method. The methods you can use depend on the design of your BLL class and method.

Method 1 - The Default Constructor

If your BLL class has a default, parameterless constructor, you can simply assign the method like this:

<asp:ObjectDataSource ID="ObjectDataSource1" runat="server" 
      SelectMethod="MySelectMethod" 
      TypeName="MyType">
</asp:ObjectDataSource>					

As you can see, you have to define the TypeName (the name of the class in your Business Layer that contains the method you want to call) and the actual name of the method for the SelectMethod property. Before that method is called, the .NET run-time will automatically create an instance of MyType by calling its default constructor (that has no parameters).

The method signature can look as simple as this:

public DataSet MySelectMethod()
{

}  

Method 2 - Static Methods

The next method uses the exact same markup as the first method, but this time the method in the Business Layer is static:

public static DataSet MySelectMethod()
{

}  

With the static method, there is no longer the need to have a default, parameter less constructor on the MyType class. If the class only contains static methods, you can even hide the constructor alltogether by marking it as private.

Method 3 - Using ObjectCreating

The next, and final method I am discussing here, is using the ObjectCreating event. This event is fired by the ObjectDataSource control just before it tries to call your method. Inside this event, you can create an instance of your custom Business class, passing it any type of information it may need to receive in its constructor. Then you assign your custom object to the ObjectInstance property of the ObjectDataSourceEventArgs parameter. The following example shows a simple example of this:

protected void ObjectDataSource1_ObjectCreating(object sender, ObjectDataSourceEventArgs e)
{
  MyType myType = new MyType(1, "SomeValue", SomeCustomObject);
  e.ObjectInstance = myType;
}