Lazy Loading

Lazy Loading is an object relational pattern which is used to defer the inialization of an object until its needed. The object will not contain all of the data, but it knows how to get all of them when they are needed.

The object to be lazily loaded is originally set to null, and every request for the object checks for null and creates it "on the fly" before returning it first,

There are four main ways you can implement Lazy Load: lazy initialization, virtual proxy, value holder, and ghost.

This is an example on how to apply lazy Initialization in your class.

public class Order<br />{<br />    private int _OrderId = 0;<br />    private int OrderId<br />    {<br />        set { _OrderId = value; }<br />        get { return _OrderId; }<br />    }<br /><br />    private Customer _Customer = null;<br />    public Customer Customer<br />    {<br />        get<br />        {    <br />            if (_Customer == null)<br />                _Customer = Customer.GetCustomerByOrderId(_OrderId); // Lazy loading the Customer<br />            return _Customer;<br />        }<br />        set { _Customer = value; }<br />    }<br />}

 In this way, the first access to the Customer property will causes the customer object to be loaded.

Note : It's not always a good practice to use lazy loading, especially if loading the object requires a lot of time and resources, like accessing a webservice. In that case it's better to deep load all the required data in the object.