发布到Wcf Web服务请求的对象为空

Question

这是我的.Net Wcf WebService Service1.cs

  [DataContract]
  public class CompositeType
  {
    string degree;
    string Stre;
    string YearOfPass;
    string Institute;      
    string StatusMessage;
    string CheckStatus;
    [DataMember]
    public string deg
    {
        get { return degree; }
        set { degree = value; }
    }

    [DataMember]
    public string stream
    {
        get
        {  return Stre;   }
        set
        { Stre = value;   }
    }

    [DataMember]
    public string yop
    {
        get
        {  return YearOfPass;  }
        set
        {  YearOfPass = value;     }
    }

    [DataMember]
    public string inst
    {
        get
        { return Institute;  }
        set
        { Institute = value; }
    }
    [DataMember]
    public string StatusMsg
    {
        get
        { return StatusMessage;}
        set
        {  StatusMessage = value; }
    }
    [DataMember]
    public string check
    { 
      get  
    {  return CheckStatus;  }
        set
        {  CheckStatus = value;  }
    }
}

这里，在Wcf中，创建了变量和方法。我使用AngularJS GET方法来调用此Wcf服务。输出是完美的。但是在AngularJS中使用POST方法，我得到：StatusMsg= "Request object is nullTestCORS_1101.CompositeType"

这是AngularJS代码：

var app = angular.module('starter', []);

app.controller('customerCtrl',function($scope,$http){
    var Composite={"deg":"s","stream":"m","inst":"t","yop":"w"};
    console.log(Composite);
    $http({
        url:'http://192.168.1.50/TestSubCors/Service1.svc/GetDataUsingDataContract',
        method: 'POST',
        data:Composite,
        headers:{'Content-Type':'application/json;charset=utf-8'}
    }).then(function(response){
        var parsed_data = angular.toJson(response);
        console.log("Success")
        console.log(parsed_data);
        $scope.events=parsed_data;
    }),function(response){
        $log.error('failure loading', errorresponse);
    }
});

为什么我得到这个空请求对象？