Question

使用MVC4，Web API，AngularJS执行应用程序时出错。错误如下：

Self referencing loop detected with type 
    'System.Data.Entity.DynamicProxies.Product_259FEB40BD6111F44AA3C3CED8DD40E7E44B22CC11A32AE621E84E2239F79B2C'. Path '[0].category.products'.

模型文件夹下的products.cs文件是：

public partial class Product
{

    [JsonIgnore] 
    [Key]
    public int ProductID { get; set; }
    public string ProductName { get; set; }
    public Nullable<int> SupplierID { get; set; }
    public Nullable<int> CategoryID { get; set; }
    public string QuantityPerUnit { get; set; }
    public Nullable<decimal> UnitPrice { get; set; }
    public Nullable<short> UnitsInStock { get; set; }
    public Nullable<short> UnitsOnOrder { get; set; }
    public Nullable<int> ReorderLevel { get; set; }
    public bool Discontinued { get; set; }

    public virtual Category Category { get; set; }
    public virtual Supplier Supplier { get; set; }
}

产品控制器是：

public class ProductController : JsonController
{
        private readonly DBEntities _db = new DBEntities();

        public ActionResult GetProduct()
        {
            var productList = _db.Products;
            return Json(productList, JsonRequestBehavior.AllowGet);
        }
    }

返回JSON并包含在产品控制器中的类是：

public class JsonController : Controller
{
    public new ActionResult Json(object data, JsonRequestBehavior behavior)
    {
        var jsonSerializerSetting = new JsonSerializerSettings
        {
            ContractResolver = new CamelCasePropertyNamesContractResolver()
        };

        if (Request.RequestType == WebRequestMethods.Http.Get && behavior == JsonRequestBehavior.DenyGet)
        {
            throw new InvalidOperationException("GET is not permitted for this request.");
        }
        var jsonResult = new ContentResult
        {
            Content = JsonConvert.SerializeObject(data, jsonSerializerSetting),
            ContentType = "application/json"
        };
        return jsonResult;

    }
}

使用AngularJS的productController.js文件是：

myApp.controller('productController',
['$scope', 'productDataService', '$location',
    function productController($scope, productDataService) {
        $scope.products = [];
        $scope.currentPage = 1;
        $scope.pageSize = 10;
        loadProductData();

        function loadProductData() {
            productDataService.getProducts()
                .then(function () {
                    $scope.products = productDataService.products;
                },
                    function () {
                        //Error goes here...
                    })
                    .then(function () {
                        $scope.isBusy = false;
                    });
            $scope.pageChangeHandler = function (num) {
                console.log('Product page changed to ' + num);
            }
        };
    }
]);

数据服务就像：

myApp.factory('productDataService', ['$http', '$q',
    function ($http, $q) {
        var _products = [];

        var _getProducts = function () {
            var deferred = $q.defer();
            var controllerQuery = "product/GetProduct";

            $http.get(controllerQuery)
                .then(function (result) {
                    // Successful
                    angular.copy(result.data, _products);
                    deferred.resolve();
                },
                    function (error) {
                        // Error
                        deferred.reject();
                    });
            return deferred.promise;
        };
        return {
            products: _products,
            getProducts: _getProducts
        };
    }
]);

相同类型的代码适用于其他应用程序但我不清楚为什么上面提到的代码不起作用。

感谢接受任何帮助。

由于帕塔

Answer 1

你可以这样做：

return new ContentResult
            {
                Content = JsonConvert.SerializeObject(data, Formatting.None, new JsonSerializerSettings {ReferenceLoopHandling = ReferenceLoopHandling.Ignore}),
                ContentType = "application/json"
            };

Answer 2

打开WebApiConfig并注册JsonFormatter

config.Formatters.JsonFormatter.SerializerSettings.ReferenceLoopHandling 
= Newtonsoft.Json.ReferenceLoopHandling.Ignore;

Answer 3

是的，这可能是由于json尝试序列化您的导航对象。

public virtual Category Category { get; set; }
public virtual Supplier Supplier { get; set; }

1.执行任务测试 来排除这种情况。

2.为它们编写一个忽略规则或为Product创建一个DTO对象，

在MVC获取＆＃34;检测到自我参考循环＆＃34;错误

3 个答案: