Problem with WCF/EF 4.1 Lazy Loading

Question

I'm getting data for my application through WCF service. And on the server side the service is using EF4.1 as a data access. Service method looks kind of like this :

public List<JobOffer> GetAllJobOffers()
{
    var allJobOffers = _jobOffersRepository.GetAll().ToList();
    return allJobOffers;
}

And the repository is done this way

public override IQueryable<JobOffer>GetAll()
{
    return _context.JobOffers.Include(c => c.Company);
}

I am getting this strange error :

An error occurred while receiving the HTTP response to http://localhost:8080/JobsService/ws. This could be due to the service endpoint binding not using the HTTP protocol. This could also be due to an HTTP request context being aborted by the server (possibly due to the service shutting down). See server logs for more details.

In debug mode after hitting F5 it starts to loop forever.

In my case it should some problem with lazy loading on the server side. Because when I am calling the service to return objects with simple structure it works like a champ. What could be messed up? And what is the best practice to eager load objects with EF ?

score 6 · Accepted Answer · edited May 23 '17 at 12:05

6

When using EF over WCF lazy loading should be turned off because serialization will trigger lazy loading of every navigation property. Another problem are cyclic references which are not serializable by default. If your Company has also navigation property to its Jobs it makes cyclic reference.

edited May 23 '17 at 12:05

Community

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answered May 13 '11 at 19:12

Ladislav Mrnka

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So you are saying that there is no way to send the whole object tree over the wire ? – Naz May 13 '11 at 19:15
There is a way but you must help WCF to serialize entities. Here are all your options: http://stackoverflow.com/questions/5762135/ef4-cause-circular-reference-in-web-service/5763627#5763627 – Ladislav Mrnka May 13 '11 at 19:54
Thank you a lot. You helped me in a most of the problems I had with EF! – Naz May 13 '11 at 20:15

score 0 · Answer 2 · answered Sep 06 '13 at 23:10

I know this is a bit of an old question, but based on your experiences in your question, I think it might help if you take a look through one of my recent posts http://sanderstechnology.com/2013/more-with-the-entity-framework-v6-rc1/12423/

I walk through how to send a semi-complex EF object graph which is deserialized through WCF, and I handle lazy loading, proxy generation and cyclic reference issues. It might be worth a look.

score 0 · Answer 3 · answered Nov 28 '11 at 13:51

I think your problem is more like to be related to the cyclic relationship. this all happens when serialization comes in scope. lets say u have e entity person which has property addresses which is marked as lazy. on the other side of relationship Addresses entity has a navigation property for Person entity. as serialization takes place it goes through each property of the person entity and as it access Addresses navigation property starts to load it. now it starts to serialize Address entity and as it access Person navigation property it goes back to that property and starts to serialize it and it creates situation when cyclic serialization starts and can not be completed. to overcome this problem u do not have to turn of lazy loading but all u have to do is to decorate you datacontract in (in this case Person and Addresse) with [DataContract(IsReference = true)] and everything works like an charm.

Problem with WCF/EF 4.1 Lazy Loading

3 Answers3

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