Asp.Net Core Webapi Returning Object List

Question

I am trying to return a list of a "Plan" Template that has a list of "Expenses", returning only the plan list works, but when added to return the spending list of a javascript error.

"Failed to load Resource: net::ERR_SPDY_PROTOCOL_ERROR"

"Uncaught (in Promise) Typeerror: Failed to fetch"

Controller

    [HttpPost]
    public IEnumerable<Plano> GetPlanos()
    {
        return db.GetPlanos()
            .AsEnumerable();
    } 

Modelo dos Gastos

[DataContract]
public class Gastos
{
    [DataMember]
    public long Id { get; set; }
    [DataMember]
    public string Descricao { get; set; }
    [DataMember]
    public TipoFrequencia Frequencia { get; set; }
    [DataMember]
    public TipoGasto Tipo { get; set; }
    [DataMember]
    public DateTime? Data { get; set; }
    [DataMember]
    public double Valor { get; set; }
    [DataMember]
    public Plano Planos { get; set; }
}

Flat Model

[DataContract]
public class Plano
{
    [DataMember]
    public long Id { get; set; }      
    [DataMember]
    public List<Gasto> Gasto { get; set; }
    [DataMember]
    public int Moradores { get; set; }

}

Javascript call

componentDidMount() {
    fetch('Plano/GetPlanos', { method: 'POST' })
        .then(response => response.json())
        .then(data => {
            console.log(data);
            this.setState({ lista: data, loading: false });
        });   
}

Query in the database

    public IQueryable<Plano> GetPlanos()
    {
        return _contexto.Planos
                    .Include(p => p.Gastos);                        
    }

Not even this console.log runs, the error happens before, if I take [Datamember] out of the spending list works.

Debugging on Asp.net da to see that it’s all right he picks up the data all right, only at the time to return to the javascript that the problem.

Answer 1

Leo, this seems like a mistake circular reference which generally creates an exception at the time of serialization. Add the line below in the method ConfigureServices class Startup.cs, this tends to solve this problem:

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