如何为Web API 2 OData数据控制器创建自定义实体

Question

我需要将传统的Web API 2数据控制器迁移到OData v4类型的数据控制器。这对于标准的一对一表到实体关系来说非常容易，但我现在需要在数据控制器响应中使用几个不同的表（它们没有真正的约束）。我很难弄清楚如何在我的WebAPI.config文件中注册这个新的自定义"实体"。

下面是我的WebAPIconfig.cs的一个示例：

using System.Linq;
using System.Web.Http;
using System.Web.OData.Builder;
using System.Web.OData.Extensions;
using System.Web.OData.Routing;
using System.Web.OData.Routing.Conventions;
using MyProject.Models;
namespace MyProject
{
    public static class WebApiConfig
    {
        public static void Register(HttpConfiguration config)
        {
            // Web API configuration and routes
            config.MapHttpAttributeRoutes();
            //OData configuration
            ODataModelBuilder builder = new ODataConventionModelBuilder();
            builder.EntitySet<Order>("orders");
            builder.EntitySet<Customer>("customers");
            //what goes here for my "custom" entity?
            var _model = builder.GetEdmModel();
            var defaultConventions = ODataRoutingConventions.CreateDefaultWithAttributeRouting(config, _model);
            //var defaultConventions = ODataRoutingConventions.CreateDefault();
            var conventions = defaultConventions.Except(
                    defaultConventions.OfType<MetadataRoutingConvention>());
            config.MapODataServiceRoute(
                routeName: "ODataRoute",
                routePrefix: "api",
                routingConventions: conventions,
                pathHandler: new DefaultODataPathHandler(),
                model: _model);         
            //ensure JSON responses
            var appXmlType = config.Formatters.XmlFormatter.SupportedMediaTypes.FirstOrDefault(t => t.MediaType == "application/xml");
            config.Formatters.XmlFormatter.SupportedMediaTypes.Remove(appXmlType);
        }
    }
}

下面是我的Web API 2数据控制器的一个示例：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web.Http;
using MyProject.Models;
namespace MyProject.DataControllers
{
    public class OrderDetailsController : ApiController
    {
        public OrderDetails GetOrderDetails(int id)
        {
            var ctx = new MyDatabaseEntities();
            var details = new OrderDetails();
            var order = ctx.Orders.FirstOrDefault(o => o.orderID == id);
            if (order == null)
            {
                return details; //return an empty details object to the UI and abandon this code
            }
            //Data objects necessary for the order details page
            IEnumerable<orderCertification> coupons = ctx.Coupons;
            var importances     = ctx.OrderImportances.Where(x => x.ImportanceId == order.ImportanceId).Where(x => (x.Type == "IMPORTANCES")) ?? null;
            var rankings        = ctx.OrderImportances.Where(x => x.ImportanceId == order.ImportanceId).Where(x => (x.Type == "RANK")) ?? null;
            var profits         = ctx.OrderImportances.Where(x => x.ImportanceId == order.ImportanceId).Where(x => (x.Type == "PROFIT")) ?? null;
            var address         = ctx.CustomerAddress.Where(c => c.OrderId == order.Id) ?? null;
            var email           = ctx.CustomerEmail.Where(c => c.Id == order.Id).Where(x => x.Type == "EMAIL") ?? null;         
            var giftcards       = ctx.GiftCardAssignments.Where(c => c.CardID == order.CardID).FirstOrDefault().ToList() ?? null;
            var customerCoupons = coupons.Where(c => giftCards.Any(o => o.GiftCardID == c.Id)).OrderBy(c => c.CouponName) ?? null;
            //lots of other fun and crazy properties get set here!! etc etc.
            //Set the order details properties 
            details.OrderImportances    = importances;
            details.OrderRankings       = rankings;
            details.OrderProfits        = profits;
            details.OrderAddress        = address;
            details.OrderEmail          = email;
            details.OrderGiftCards      = giftcards;
            details.OrderCoupons        = customerCoupons;
            details.OrderDescription    = "This is my order description string.";
            return details;
        }
    }
}

下面是我的OrderDetails（）类当前的样子：

using System.Collections.Generic;
namespace MyProject.Models
{
    public class OrderDetails
    {
        public IEnumerable<OrderImportance> OrderImportances { get; set; }
        public IEnumerable<OrderImportance> OrderRankings { get; set; }
        public IEnumerable<OrderImportance> OrderProfits { get; set; }
        public string OrderAddress { get; set; }
        public string OrderEmail { get; set; }
        public IEnumerable<OrderGiftCard> OrderGiftCards { get; set; }
        public IEnumerable<OrderCoupon> OrderCoupons { get; set; }
        public string OrderDescription { get; set; }
    }
}

如何制作此Web API控制器的OData版本，以及如何在WebAPIConfig.cs中为其注册OrderDetails类？

Answer 1

OrderDetails似乎没有键属性。因此，它不是实体类型（带键的命名结构化类型），而是复杂类型[由一组属性组成的无键命名结构化类型]。

由于复杂类型没有自己的标识（即密钥），因此它们不能作为OData服务中的实体集公开。这意味着您将不会在模型生成器中配置OrderDetails，也不会为OrderDetails创建单独的控制器。

将现有的GetOrderDetails方法迁移到OData的最简单方法是将其重新定义为绑定到orders实体集的OData函数。OData v4中的操作和函数使用ASP.NET Web API 2.2提供了一个关于定义和配置OData函数的良好教程，但以下是您需要做的要点

在WebApiConfig.Register:中声明函数

builder.EntityType<Order>().Function("GetOrderDetails").Returns<OrderDetails>();

在控制器中为orders实体集定义功能：

public class OrdersController : ODataController
{
    // Other methods for GET, POST, etc., go here.
    [HttpGet]
    public OrderDetails GetOrderDetails([FromODataUri] int key)
    {
        // Your application logic goes here.
    }
}

最后，调用函数如下：

GET http://host/api/orders(123)/Default.GetOrderDetails

请注意，Default是服务的默认命名空间，在调用绑定函数时通常需要它。要更改此设置，可以设置builder.Namespace，也可以使用config.EnableUnqualifiedNameCall(true)启用不合格的函数调用。