CODEWITHSUNDEEP
asp.net-mvcentity-frameworklazy-loading
managerger
managerger

Reputation: 790

Real examples of using EF lazy loading in MVC application

Can anyone post correct and useful an example of using EF lazy loading in MVC application?

I've tried to research the question, but I can't get proper case.

As a result my conclusion is: since web apps are stateless there is no sense to include LL to entities. But it sounds strange. That's why the question is here.

Can you confirm or otherwise refute my conclusion?

EDIT

The statment "stateless" in question context is important in my mind. Let's pretend 2 scenarios. First one relates for example to WPF app and the second one to MVC. Let's suppose that thre is the next simple object:

public class Person 
{ 
    public int Age { get; set; } 
    public string Name { get; set; } 
    ... 
    public virtual List<Activity> Activities { get; set; } 
}

1) WPF. User is able to request the only Person without his Activities. Thus he get a small portion of data. Overhead are reasonable. At the same time user can decide to request person's activities. Due to ll mechanism, EF simply loads activities without requesting person object again, since Person still exists in application (of course, if we code it in such a way).

2) MVC. The same actions are there. But the only difference that, after server response, all resources including object Person are disposes. And we can't load Person activities as we did in WPF application. We are forced to load Person again (overhead is increases comparing with WPF app)

The point is that Lazy loading can be executed only in the scope of the context to which the entity is attached - if you dispose the context you cannot use it.

Upvotes: 0

Views: 1110

Answers (1)

Chris Pratt
Chris Pratt

Reputation: 239290

I don't think you understand what lazy loading does, as it has nothing to do with whether there's any state or not. It's not like caching or something. Lazy loading is simply Entity Framework overloading a property to add a custom getter that issues a query to fetch the object or set of objects when the property is accessed for the first time.

For example, if you had something like:

public class Foo 
{
    public virtual Bar Bar { get; set; }
}

And you were to query a set of Foos from the database, the Bar property on all of them would be null, as EF would not have issued any queries yet to fetch the related Bar instance. However, if you were to iterate over this list of Foo and access some property on Bar (i.e. foo.Bar.Baz, then EF would issue a just-in-time query for the Bar instance, so that it could then return the Baz property on it.

Upvotes: 2

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