.Net Core WebAPI connection reset, when I have "include" in my controller

Question

I have a new project with .Net Core. It's a WebAPI project. And I have a separate project for my model.

In WebAPI project, in a controller, I have something like this:

    // GET: api/questions
    [HttpGet]
    public IEnumerable<Question> GetQuestions()
    {
        return _context.Questions
            .Include( i => i.QuestionType );
    }

When I call http://localhost:55555/api/questios/ it just returns the first record, and then this error message: Recv failure: Connection was reset

If I remove the Include part and just return the _context.Questions, it work just fine!

What's wrong in my code?

Is LazyLoading enabled? Maybe you can just flat the entities to a List object in order to understand the reason. — ali, Jun 02 '17 at 07:13
To debug this, wrap the return in a try/catch and then add .ToList() after the .Include — robjam, Jun 02 '17 at 07:30
How do you inject your context in your controller ? By the DI service ? — AdrienTorris, Jun 02 '17 at 08:41
Take a look to this issue, it can be the same error : https://github.com/aspnet/Mvc/issues/5910 — AdrienTorris, Jun 02 '17 at 08:47

Rahmani · Accepted Answer · 2017-06-02T10:07:03.100

13

I've found the answer. Thank you everyone who helped.

I added json options according to Loading related data

If you are using ASP.NET Core, you can configure Json.NET to ignore cycles that it finds in the object graph. This is done in the ConfigureServices(...) method in Startup.cs.

            services.AddMvc()
              .AddJsonOptions(
                    options => options.SerializerSettings.ReferenceLoopHandling
                        = Newtonsoft.Json.ReferenceLoopHandling.Ignore );

edited Jun 02 '17 at 10:07

answered Jun 02 '17 at 09:37

Rahmani

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2

I found this solved my problem, but then I found another way which I think I prefer. I added the `[JsonIgnore]` decorator to the properties that I didn't want to serialize and there were no longer any loops to worry about. I suspect this is usually the reference from a child back to its parent. See this answer for more details: https://stackoverflow.com/a/11851461/5322405 – Ken Lyon May 01 '18 at 18:26
Awesome addition, @KenLyon. I'm not yet sure this is my exact problem here, but I've been using `ReferenceLoopHandling.Ignore` and much prefer the decorator solution. – Auspex Jan 16 '19 at 16:57
1

Ah! I discovered that I did, in fact, have `ReferenceLoopHandling.Ignore` set in `services.AddMvc()`, but because I had added `JsonSerializerSettings` in a _specific_ Json() call, it was being overridden. – Auspex Jan 16 '19 at 17:19

Andreas Zita · Answer 2 · 2017-06-02T08:42:27.013

0

Try this:

// GET: api/questions
[HttpGet]
public IEnumerable<Question> GetQuestions()
{
    var res = _context.Questions
        .Include( i => i.QuestionType ).ToArray();
    return res;
}

edited Jun 02 '17 at 08:42

answered Jun 02 '17 at 08:22

Andreas Zita

7,232
6
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It's the same as before. – Rahmani Jun 02 '17 at 08:33
Can you Include other related entities? Or do you get the same error for everything you include? – Andreas Zita Jun 02 '17 at 08:37
I have updated the code. Try and debug this with a break point to watch the "res" variable. – Andreas Zita Jun 02 '17 at 08:43

.Net Core WebAPI connection reset, when I have "include" in my controller

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