Can you explain the concept of lazy data loading and in what cases it is applied?

Lazy Loading is a pattern where the loading or initialization of a resource occurs not immediately, but only at the moment of the first access to it. This helps save resources and speed up program startup by loading heavy objects only when necessary.

In C#, lazy loading is often implemented using the Lazy<T> class, which encapsulates the logic of object creation and guarantees that the object will be created only upon the first access to the Value property.

Example:

Lazy<HeavyObject> lazyObject = new Lazy<HeavyObject>(() => new HeavyObject());

// HeavyObject is not created until we call:
var obj = lazyObject.Value; // Initialization occurs here

Lazy loading is used when:

• Creating the object is costly in terms of time or resources.
• The object may not be needed during execution.
• To optimize memory usage and performance.

In ORM (e.g., Entity Framework), lazy loading is used to load related data from the database only when accessed, not immediately upon loading the main object.