c# - Can't serialize an object with Json.Net -

i have following object , trying serialize json json.net

[serializable] public class flightselection : iequatable<flightselection> {     public static readonly datetime initialdate;      public flightselection();      public flightweekselectiontype flightweekselectiontype { get; set; }     public bool isvalidproposallineweeksexists { get; }     public int play { get; set; }     public list<proposallineweek> proposallineweeks { get; set; }     public int selectedcount { get; }     public int skip { get; set; }      public void applypattern();     public bool equals(flightselection other);     public override bool equals(object obj);     public bool[] toboolarray();     public override string tostring(); } 

i try serialize following code:

var jssettings = new jsonserializersettings(); var fs = new flightselection(); string json = jsonconvert.serializeobject(fs, formatting.none, jssettings); 

i following error: the 'obj' argument not flightselection object.

i can't understand why. place in object see 'obj' in equals method. why serializer care method.

am missing simple?

edit: stack trace requested in comments:

at cc.fusion.business.model.flightselection.equals(object obj) @ system.collections.generic.objectequalitycomparer1.indexof(t[] array, t value, int32 startindex, int32 count) @ system.array.indexof[t](t[] array, t value, int32 startindex, int32 count) @ system.collections.generic.list1.indexof(t item) @ newtonsoft.json.serialization.jsonserializerinternalwriter.checkforcircularreference(jsonwriter writer, object value, jsonproperty property, jsoncontract contract, jsoncontainercontract containercontract, jsonproperty containerproperty) @ newtonsoft.json.serialization.jsonserializerinternalwriter.calculatepropertyvalues(jsonwriter writer, object value, jsoncontainercontract contract, jsonproperty member, jsonproperty property, jsoncontract& membercontract, object& membervalue) @ newtonsoft.json.serialization.jsonserializerinternalwriter.serializeobject(jsonwriter writer, object value, jsonobjectcontract contract, jsonproperty member, jsoncontainercontract collectioncontract, jsonproperty containerproperty) @ newtonsoft.json.serialization.jsonserializerinternalwriter.serializevalue(jsonwriter writer, object value, jsoncontract valuecontract, jsonproperty member, jsoncontainercontract containercontract, jsonproperty containerproperty) @ newtonsoft.json.serialization.jsonserializerinternalwriter.serializeobject(jsonwriter writer, object value, jsonobjectcontract contract, jsonproperty member, jsoncontainercontract collectioncontract, jsonproperty containerproperty) @ newtonsoft.json.serialization.jsonserializerinternalwriter.serializevalue(jsonwriter writer, object value, jsoncontract valuecontract, jsonproperty member, jsoncontainercontract containercontract, jsonproperty containerproperty) @ newtonsoft.json.serialization.jsonserializerinternalwriter.serializelist(jsonwriter writer, ienumerable values, jsonarraycontract contract, jsonproperty member, jsoncontainercontract collectioncontract, jsonproperty containerproperty) @ newtonsoft.json.serialization.jsonserializerinternalwriter.serializevalue(jsonwriter writer, object value, jsoncontract valuecontract, jsonproperty member, jsoncontainercontract containercontract, jsonproperty containerproperty) @ newtonsoft.json.serialization.jsonserializerinternalwriter.serializeobject(jsonwriter writer, object value, jsonobjectcontract contract, jsonproperty member, jsoncontainercontract collectioncontract, jsonproperty containerproperty) @ newtonsoft.json.serialization.jsonserializerinternalwriter.serializevalue(jsonwriter writer, object value, jsoncontract valuecontract, jsonproperty member, jsoncontainercontract containercontract, jsonproperty containerproperty) @ newtonsoft.json.serialization.jsonserializerinternalwriter.serialize(jsonwriter jsonwriter, object value, type objecttype) @ newtonsoft.json.jsonserializer.serializeinternal(jsonwriter jsonwriter, object value, type objecttype) @ newtonsoft.json.jsonserializer.serialize(jsonwriter jsonwriter, object value, type objecttype) @ newtonsoft.json.jsonconvert.serializeobject(object value, type type, formatting formatting, jsonserializersettings settings) @ newtonsoft.json.jsonconvert.serializeobject(object value, formatting formatting, jsonserializersettings settings) @ approxyserver.approxy.getproposal(int32 proposalid) in c:\code.net\clearchannel\sandbox\approxyserver\approxy\approxy.svc.cs:line 194 @ syncinvokegetproposal(object , object[] , object[] ) @ system.servicemodel.dispatcher.syncmethodinvoker.invoke(object instance, object[] inputs, object[]& outputs) @ system.servicemodel.dispatcher.dispatchoperationruntime.invokebegin(messagerpc& rpc)

i looked @ code indicated (pastebin.com/wqkp45mr) if change implementation of equals method coming iequitable contract in following way, works

public override bool equals(object obj)     {          //if (obj == null) return base.equals(obj);          //if (!(obj flightselection))         //    throw new invalidcastexception("the 'obj' argument not flightselection object.");         //else         //    return equals(obj flightselection);              var flightselection = obj flightselection;         if (flightselection == null)             return false;         return equals(flightselection);     } 

the result obtained :

{"flightweekselectiontype":0,"play":1,"proposallineweeks":[],"selectedcount":0," skip":1,"isvalidproposallineweeksexists":false} press key continue . . . 

i hope helps...

edit :

if can't modify source code following works ok , tested too.

    class program     {         static void main(string[] args)         {             var jssettings = new jsonserializersettings();             var fs = new angryhackerflightselection();             string json = jsonconvert.serializeobject(fs, newtonsoft.json.formatting.none, jssettings);             console.writeline(json);         }     }      public class angryhackerflightselection : flightselection     {         public override bool equals(object obj)         {             var flightselection = obj flightselection;             if (flightselection == null)                 return false;             return equals(flightselection);         }     }