CODEWITHSUNDEEP
c#.netasp.net-mvcentity-framework
Kevin Nelson
Kevin Nelson

Reputation: 7673

Correct way to check if greedily-loaded Entity was loaded after context disposed?

Probably not pertinent, but I'm using:

.NET MVC 5.2.3 w/ Razor 3.2.3, Entity Framework 6.1.3 Code First, Visual Studio 2015.

Okay, in my controller method, I have--in essence, but dumbed down for conciseness:

using( var context = new MyContext() ) {
    var person = context.Persons.Include( x => x.PostalCode ).FirstOrDefault();
    return View(person);
}

Now, originally the Zip data entry property was not a foreign key...just whatever 5-digit string the user entered. Now, however, it's a foreign key, in essence, so that we can get postal-code information.

public string Zip { get; set; }
[ForeignKey("Zip")]
public virtual PostalCode PostalCode { get; set; }

Not ideal structure...I know...

But anyway, if the user has a postal-code recognized by our system, all great, everything loads. However, if the user has an unknown or invalid zip code, e.g. 00000, EF sees a non-null Foreign Key and this results in the following problem:

In my view-file (so after I've disposed of my context), I check the property of our greedily-loaded entity:

@if( person.PostalCode != null && person.PostalCode.IsInServiceArea ) {
    <div>Service Area HTML</div>
}

Unfortunately, because of EF overriding my virtual property, even when there is no PostalCode, it's not NULL. So, when this code runs it throws an exception that the ObjectContext has been disposed of, which means that EF is trying to lazy-load an Entity even though it already tried to greedily load and should know it doesn't exist :(

The obvious solutions (please don't answer w/ these):

The Question

In Entity Framework, Code-First, what is the correct way to check to see if a greedily loaded, LEFT OUTER JOIN'd entity, was loaded AFTER the context is disposed of?

Based on answers I have found, (e.g. the below), I'm thinking it's likely that this is not possible without the context being open...but thought I'd ask anyway:

Upvotes: 2

Views: 424

Answers (2)

Akos Nagy
Akos Nagy

Reputation: 4359

So, referring back to my comment, you can disable lazy-loading and proxy creation altogether. Just find the constructor(s) of your dbcontext type, and then add these two lines into the method:

this.Configuration.LazyLoadingEnabled = false;
this.Configuration.ProxyCreationEnabled = false;

This way you can disable it globally (whenever a context is created the ctor is run, these settings are applied).

Or, you can just disable it for one instance if you set these on the context object itself after it's created.

Upvotes: 1

jimSampica
jimSampica

Reputation: 12420

Alternatively let your context live through the entire request so that lazy loading can be fulfilled on the view.

Startup.Auth.cs

public void ConfigureAuth(IAppBuilder app)
{
    MyContext Create() { return new MyContext(); }
    app.CreatePerOwinContext(Create);
    ...
}

MyController.cs

var context = HttpContext.GetOwinContext().Get<MyContext>();
var person = context.Persons.Include( x => x.PostalCode ).FirstOrDefault();
return View(person);

Upvotes: 0

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