Circular reference detected while serializing an object - C#, Json

Question

I'm trying to serialise an object to return it in Json format in order to create a graph. I am doing this in a class library and returning the string as part of a bigger report. I am getting an error however that says:

A circular reference was detected while serializing an object of type 'MyApp.Data.Shop'.

I was following this tutorial and expected a similar Json string to be returned (with more fields of course) - Tutorial

The error is being thrown in this method in my reportengine -

public string GetMonthlyShopSalesJson(List<Sale> sales, MonthlyRequest reportRequest)
{
    List<MonthlyShopSales> mrs = GetMonthlyShopSales(sales, reportRequest);

    JavaScriptSerializer serializer = new JavaScriptSerializer();
    string jsonData = serializer.Serialize(mrs); //Error line

    return jsonData;
}

Here is my method for retrieving the shopsales:

public List<MonthlyShopSales> GetMonthlyShopSales(List<Sale> sales, MonthlyRequest reportRequest)
{
    ModelContainer ctn = new ModelContainer();
    MonthlyDateRange dates = GetComparativeDateRange(reportRequest);

    List<MonthlyShopSales> shopSales = (from sale in sales
                                        orderby sale.Shop.Name
                                        group sale by sale.Shop into ret
                                        select new MonthlyShopSales
                                        {
                                            Shop = ret.Key,
                                            TotalNumItemsSoldUSD = ret.Where(it => it.USDCut.HasValue).Where(it => it.USDCut != 0).Count(),
                                            TotalNumItemsSoldGBP = ret.Where(it => it.GBPCut.HasValue).Where(it => it.GBPCut != 0).Count(),
                                            TotalNumItemsSoldEUR = ret.Where(it => it.EURCut.HasValue).Where(it => it.EURCut != 0).Count(),
                                            USDTotalEarnings = PerformCurrencyConversion(ret.Sum(it => it.USDCut.HasValue ? it.USDCut.Value : 0), 0M, 0M, reportRequest.Currency, dates.BaseStartDate),
                                            GBPTotalEarnings = PerformCurrencyConversion(0M, ret.Sum(it => it.GBPCut.HasValue ? it.GBPCut.Value : 0), 0M, reportRequest.Currency, dates.BaseStartDate),
                                            EURTotalEarnings = PerformCurrencyConversion(0M, 0M, ret.Sum(it => it.EURCut.HasValue ? it.EURCut.Value : 0), reportRequest.Currency, dates.BaseStartDate),
                                            TotalNumItemsSoldUSDOverall = sales.Where(it => it.USDCut.HasValue).Where(it => it.USDCut != 0).Count(),
                                            TotalNumItemsSoldGBPOverall = sales.Where(it => it.GBPCut.HasValue).Where(it => it.GBPCut != 0).Count(),
                                            TotalNumItemsSoldEUROverall = sales.Where(it => it.EURCut.HasValue).Where(it => it.EURCut != 0).Count(),
                                            USDTotalEarningsOverall = PerformCurrencyConversion(sales.Sum(it => it.USDCut.HasValue ? it.USDCut.Value : 0), 0M, 0M, reportRequest.Currency, dates.BaseStartDate),
                                            GBPTotalEarningsOverall = PerformCurrencyConversion(0M, sales.Sum(it => it.GBPCut.HasValue ? it.GBPCut.Value : 0), 0M, reportRequest.Currency, dates.BaseStartDate),
                                            EURTotalEarningsOverall = PerformCurrencyConversion(0M, 0M, sales.Sum(it => it.EURCut.HasValue ? it.EURCut.Value : 0), reportRequest.Currency, dates.BaseStartDate)
                                        }).ToList();
    return shopSales;
}

And then here is my class for the MonthlyShopSales:

public class MonthlyShopSales
{
    public Shop Shop { get; set; }

    public int TotalNumItemsSoldUSD { get; set; }
    public int TotalNumItemsSoldGBP { get; set; }
    public int TotalNumItemsSoldEUR { get; set; }
    public int NumberOfItemsSoldPerShop { get { return TotalNumItemsSoldUSD + TotalNumItemsSoldGBP + TotalNumItemsSoldEUR; } }

    public decimal USDTotalEarnings { get; set; }
    public decimal GBPTotalEarnings { get; set; }
    public decimal EURTotalEarnings { get; set; }

    public decimal OverallEarningsPerShop { get { return USDTotalEarnings + GBPTotalEarnings + EURTotalEarnings; } }

    public decimal QtyPercentageOfSales { get { return ((decimal)NumberOfItemsSoldPerShop / (decimal)TotalNumberOfBooksSoldOverall) * 100; } }
    public decimal RevenuePercentageOfSales { get { return (OverallEarningsPerShop / TotalEarningsOverall) * 100; } }

    public int TotalNumItemsSoldUSDOverall { get; set; }
    public int TotalNumItemsSoldGBPOverall { get; set; }
    public int TotalNumItemsSoldEUROverall { get; set; }
    public int TotalNumberOfItemsSoldOverall { get { return TotalNumItemsSoldUSDOverall + TotalNumItemsSoldGBPOverall + TotalNumItemsSoldEUROverall; } }

    public decimal USDTotalEarningsOverall { get; set; }
    public decimal GBPTotalEarningsOverall { get; set; }
    public decimal EURTotalEarningsOverall { get; set; }

    public decimal TotalEarningsOverall { get { return USDTotalEarningsOverall + GBPTotalEarningsOverall + EURTotalEarningsOverall; } }
}

I'm trying to be relatively efficient with the code I'm writing, which is why I'm using the GetMonthlyShopSales method twice - I don't necessarily need all it's values so should I write a separate, more cut down version for my Json string? I am also not sure if this is my problem or not so if someone could help with that it would be great.

Here is the stack trace for anyone who is good at reading that:

[InvalidOperationException: A circular reference was detected while serializing an object of type 'MyApp.Data.Shop'.]
   System.Web.Script.Serialization.JavaScriptSerializer.SerializeValueInternal(Object o, StringBuilder sb, Int32 depth, Hashtable objectsInUse, SerializationFormat serializationFormat) +1549
   System.Web.Script.Serialization.JavaScriptSerializer.SerializeValue(Object o, StringBuilder sb, Int32 depth, Hashtable objectsInUse, SerializationFormat serializationFormat) +194
   System.Web.Script.Serialization.JavaScriptSerializer.SerializeCustomObject(Object o, StringBuilder sb, Int32 depth, Hashtable objectsInUse, SerializationFormat serializationFormat) +502
   System.Web.Script.Serialization.JavaScriptSerializer.SerializeValueInternal(Object o, StringBuilder sb, Int32 depth, Hashtable objectsInUse, SerializationFormat serializationFormat) +1424
   System.Web.Script.Serialization.JavaScriptSerializer.SerializeValue(Object o, StringBuilder sb, Int32 depth, Hashtable objectsInUse, SerializationFormat serializationFormat) +194
   System.Web.Script.Serialization.JavaScriptSerializer.SerializeEnumerable(IEnumerable enumerable, StringBuilder sb, Int32 depth, Hashtable objectsInUse, SerializationFormat serializationFormat) +126
   System.Web.Script.Serialization.JavaScriptSerializer.SerializeValueInternal(Object o, StringBuilder sb, Int32 depth, Hashtable objectsInUse, SerializationFormat serializationFormat) +1380
   System.Web.Script.Serialization.JavaScriptSerializer.SerializeValue(Object o, StringBuilder sb, Int32 depth, Hashtable objectsInUse, SerializationFormat serializationFormat) +194
   System.Web.Script.Serialization.JavaScriptSerializer.SerializeCustomObject(Object o, StringBuilder sb, Int32 depth, Hashtable objectsInUse, SerializationFormat serializationFormat) +502
   System.Web.Script.Serialization.JavaScriptSerializer.SerializeValueInternal(Object o, StringBuilder sb, Int32 depth, Hashtable objectsInUse, SerializationFormat serializationFormat) +1424
   System.Web.Script.Serialization.JavaScriptSerializer.SerializeValue(Object o, StringBuilder sb, Int32 depth, Hashtable objectsInUse, SerializationFormat serializationFormat) +194
   System.Web.Script.Serialization.JavaScriptSerializer.SerializeCustomObject(Object o, StringBuilder sb, Int32 depth, Hashtable objectsInUse, SerializationFormat serializationFormat) +502
   System.Web.Script.Serialization.JavaScriptSerializer.SerializeValueInternal(Object o, StringBuilder sb, Int32 depth, Hashtable objectsInUse, SerializationFormat serializationFormat) +1424
   System.Web.Script.Serialization.JavaScriptSerializer.SerializeValue(Object o, StringBuilder sb, Int32 depth, Hashtable objectsInUse, SerializationFormat serializationFormat) +194
   System.Web.Script.Serialization.JavaScriptSerializer.SerializeEnumerable(IEnumerable enumerable, StringBuilder sb, Int32 depth, Hashtable objectsInUse, SerializationFormat serializationFormat) +126
   System.Web.Script.Serialization.JavaScriptSerializer.SerializeValueInternal(Object o, StringBuilder sb, Int32 depth, Hashtable objectsInUse, SerializationFormat serializationFormat) +1380
   System.Web.Script.Serialization.JavaScriptSerializer.SerializeValue(Object o, StringBuilder sb, Int32 depth, Hashtable objectsInUse, SerializationFormat serializationFormat) +194
   System.Web.Script.Serialization.JavaScriptSerializer.Serialize(Object obj, StringBuilder output, SerializationFormat serializationFormat) +26
   System.Web.Script.Serialization.JavaScriptSerializer.Serialize(Object obj, SerializationFormat serializationFormat) +74
   System.Web.Script.Serialization.JavaScriptSerializer.Serialize(Object obj) +6
   MyApp.Business.Reporting.AdvancedReportingEngine.GetMonthlyShopSalesJson(List`1 sales, MonthlyRequest reportRequest) in  C:\Development\MyApp\MyApp.Business\Reporting\AdvancedReportingEngine.cs:75
   MyApp.Business.Reporting.AdvancedReportingEngine.GetMonthlyReport(MonthlyRequest reportRequest) in  C:\Development\MyApp\MyApp.Business\Reporting\AdvancedReportingEngine.cs:61
   MyApp.Web.Areas.User.Controllers.ReportsController.MonthlyDashboardReport(MonthlyRequest reportRequest, FormCollection formValues) in C:\Development\MyApp\MyApp.Web\Areas\User\Controllers\ReportsController.cs:34
   lambda_method(Closure , ControllerBase , Object[] ) +157
   System.Web.Mvc.ActionMethodDispatcher.Execute(ControllerBase controller, Object[] parameters) +17
   System.Web.Mvc.ReflectedActionDescriptor.Execute(ControllerContext controllerContext, IDictionary`2 parameters) +208
   System.Web.Mvc.ControllerActionInvoker.InvokeActionMethod(ControllerContext controllerContext, ActionDescriptor actionDescriptor, IDictionary`2 parameters) +27
   System.Web.Mvc.<>c__DisplayClass15.<InvokeActionMethodWithFilters>b__12() +55
   System.Web.Mvc.ControllerActionInvoker.InvokeActionMethodFilter(IActionFilter filter, ActionExecutingContext preContext, Func`1 continuation) +263
   System.Web.Mvc.<>c__DisplayClass17.<InvokeActionMethodWithFilters>b__14() +19
   System.Web.Mvc.ControllerActionInvoker.InvokeActionMethodWithFilters(ControllerContext controllerContext, IList`1 filters, ActionDescriptor actionDescriptor, IDictionary`2 parameters) +191
   System.Web.Mvc.ControllerActionInvoker.InvokeAction(ControllerContext controllerContext, String actionName) +343
   System.Web.Mvc.Controller.ExecuteCore() +116
   System.Web.Mvc.ControllerBase.Execute(RequestContext requestContext) +97
   System.Web.Mvc.ControllerBase.System.Web.Mvc.IController.Execute(RequestContext requestContext) +10
   System.Web.Mvc.<>c__DisplayClassb.<BeginProcessRequest>b__5() +37
   System.Web.Mvc.Async.<>c__DisplayClass1.<MakeVoidDelegate>b__0() +21
   System.Web.Mvc.Async.<>c__DisplayClass8`1.<BeginSynchronous>b__7(IAsyncResult _) +12
   System.Web.Mvc.Async.WrappedAsyncResult`1.End() +62
   System.Web.Mvc.<>c__DisplayClasse.<EndProcessRequest>b__d() +50
   System.Web.Mvc.SecurityUtil.<GetCallInAppTrustThunk>b__0(Action f) +7
   System.Web.Mvc.SecurityUtil.ProcessInApplicationTrust(Action action) +22
   System.Web.Mvc.MvcHandler.EndProcessRequest(IAsyncResult asyncResult) +60
   System.Web.Mvc.MvcHandler.System.Web.IHttpAsyncHandler.EndProcessRequest(IAsyncResult result) +9
   System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +8970061
   System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +184

EDIT:

As requested, here is the shop class. It is derived from an EF data model but there's only 3/4 fields in it anyhow:

[MetadataType(typeof(ShopMetadata))]
public partial class Shop
{

}

public partial class ShopMetadata
{
    [DisplayName("Shop Name")]
    [Required(ErrorMessage = "You must specify a Shop name")]
    public string Name { get; set; }

    [DisplayName("Region")]
    [Required(ErrorMessage = "You must specify a region")]
    public int Region { get; set; }

    [DisplayName("Display Sequence")]
    [Required(ErrorMessage = "You must specify a dispay sequence")]
    public int DisplaySequence { get; set; }
}

Answer 1

I suspect the problem is due to the Shop EF POCO class. Entity framework adds alot of other stuff behind the scenes. So even though your shop class my only have 3/4 properties, under the hood it probably has alot more. See:

Entity framework serialize POCO to JSON

Some people suggest Json.NET, or you can use a shop DTO class, and replace the Shop object in MonthlyShopSales with the DTO version.

Answer 2

have a look here, it might help.

On another hand, I've dealt with both Microsoft deserializer and json.net. I think json.net is a way more effective and faster. There is also fastjson library.