WebApi oData v3 实体数据模型路由答案

【问题标题】：WebApi oData v3 Entity Data Model routingWebApi oData v3 实体数据模型路由
【发布时间】：2018-06-29 15:24:48
【问题描述】：

我已经构建了 MVC4 应用程序，并希望在名为 Api 的单独区域中添加带有 OData v3 的 Asp.Net WebApi，但是在使用 EF 集进行路由时，我能够看到 $metadata 但无法从 Get 操作中获得结果。如果我在浏览器中按此 url (http://localhost:1254/odata/$metadata)，我会得到以下输出。

This XML file does not appear to have any style information associated with it. 

The document tree is shown below.
<edmx:Edmx xmlns:edmx="http://schemas.microsoft.com/ado/2007/06/edmx" Version="1.0">
<script id="tinyhippos-injected"/>
<edmx:DataServices xmlns:m="http://schemas.microsoft.com/ado/2007/08/dataservices/metadata" m:DataServiceVersion="3.0" m:MaxDataServiceVersion="3.0">
<Schema xmlns="http://schemas.microsoft.com/ado/2009/11/edm" Namespace="SchoolProject.DAL">
<EntityType Name="NewsAnnouncement">
<Key>
<PropertyRef Name="Id"/>
</Key>
<Property Name="Id" Type="Edm.String" Nullable="false"/>
<Property Name="Title" Type="Edm.String"/>
<Property Name="Image" Type="Edm.String"/>
<Property Name="Description" Type="Edm.String"/>
<Property Name="PublishDate" Type="Edm.DateTime" Nullable="false"/>
<Property Name="CreatedDate" Type="Edm.DateTime" Nullable="false"/>
<Property Name="UserName" Type="Edm.String"/>
<Property Name="ShortDescription" Type="Edm.String"/>
</EntityType>
</Schema>
<Schema xmlns="http://schemas.microsoft.com/ado/2009/11/edm" Namespace="Default">
<EntityContainer Name="Container" m:IsDefaultEntityContainer="true">
<EntitySet Name="NewsAnnouncements" EntityType="SchoolProject.DAL.NewsAnnouncement"/>
</EntityContainer>
</Schema>
</edmx:DataServices>
</edmx:Edmx>

但是当我通过实际 uri http://localhost:1245/odata/NewsAnnouncements 获取操作时，我得到以下输出

{"Message":"No HTTP resource was found that matches the request URI 'http://localhost:1245/odata/NewsAnnouncements'.","MessageDetail":"No type was found that matches the controller named 'NewsAnnouncements'."}

这是 WebApiConfig.Cs 文件的一部分

public static void Register(HttpConfiguration config)
        {
            ODataModelBuilder modelBuilder = new ODataConventionModelBuilder();
            modelBuilder.EntitySet<NewsAnnouncement>("NewsAnnouncements");

            config.Routes.MapODataServiceRoute(routeName: "ODataRoute",
                routePrefix: "odata",
                model: modelBuilder.GetEdmModel(),
                pathHandler: new DefaultODataPathHandler());

            config.Formatters.Remove(config.Formatters.XmlFormatter);
            config.EnsureInitialized();
            config.IncludeErrorDetailPolicy = IncludeErrorDetailPolicy.LocalOnly;
            config.IncludeErrorDetailPolicy = IncludeErrorDetailPolicy.Always;
        }

已编辑：

 public class NewsController : ODataController
{
    //
    // GET: /News/
    private SchoolEntities entities = new SchoolEntities();

    private bool NewsExists(string key)
    {
        return entities.NewsAnnouncements.Any(p => p.Id == key);
    }


    //
    //
    // The parameterless version of the Get method returns the entire Products collection. The Get method with a key parameter looks up a product by its key (in this case, the Id property).
    //The [EnableQuery] attribute enables clients to modify the query, by using query options such as $filter, $sort, and $page
    [EnableQuery]
    public IQueryable<NewsAnnouncement> Get()

    {
        return entities.NewsAnnouncements;
    }
    [EnableQuery]
    public SingleResult<NewsAnnouncement> Get([FromODataUri] string key)
    {
        IQueryable<NewsAnnouncement> result = entities.NewsAnnouncements.Where(p => p.Id == key);
        return SingleResult.Create(result);
    }

    //To enable clients to add a new product to the database, add the following method to ProductsController.
    public async Task<IHttpActionResult> Post(NewsAnnouncement newsItem)
    {
        if (!ModelState.IsValid)
        {
            return BadRequest(ModelState);
        }
        entities.NewsAnnouncements.Add(newsItem);
        await Task.Delay(10);
        entities.SaveChanges();
        return Created(newsItem);
    }

    //PATCH performs a partial update. The client specifies just the properties to update.

    public async Task<IHttpActionResult> Patch([FromODataUri] string key, Delta<NewsAnnouncement> product)
    {
        if (!ModelState.IsValid)
        {
            return BadRequest(ModelState);
        }
        var entity = entities.NewsAnnouncements.Find(key);
        if (entity == null)
        {
            return NotFound();
        }
        product.Patch(entity);
        try
        {
            await Task.Delay(10);
            entities.SaveChanges();
        }
        catch (DbUpdateConcurrencyException)
        {
            if (!NewsExists(key))
            {
                return NotFound();
            }
            else
            {
                throw;
            }
        }
        return Updated(entity);
    }


    public async Task<IHttpActionResult> Put([FromODataUri] string key, NewsAnnouncement updateNews)
    {
        if (!ModelState.IsValid)
        {
            return BadRequest(ModelState);
        }
        if (key != updateNews.Id)
        {
            return BadRequest();
        }
        entities.Entry(updateNews).State = EntityState.Modified;
        try
        {
            await Task.Delay(10);
            entities.SaveChanges();
        }
        catch (DbUpdateConcurrencyException)
        {
            if (!NewsExists(key))
            {
                return NotFound();
            }
            else
            {
                throw;
            }
        }
        return Updated(updateNews);
    }

    // Notice that the controller overrides the Dispose method to dispose of the EntitiesContext.
    protected override void Dispose(bool disposing)
    {
        entities.Dispose();
        base.Dispose(disposing);
    }

}

任何建议都将受到高度赞赏。谢谢。

【问题讨论】：

你能告诉我们你的控制器吗？
@donMateo 请检查我已发布控制器代码的编辑代码。谢谢。

标签： c# asp.net-mvc entity-framework asp.net-mvc-4 asp.net-web-api

【解决方案1】：

最后我在手动添加控制器名称时找到了答案，它与复数实体集“NewsAnnouncements”不同，这就是它显示错误的原因。我将控制器名称更改为类似于实体集“NewsAnnouncementsController”而不是“NewsController”。一切都像魅力一样运作。

正确的控制器应该是这样的

 public class NewsAnnouncementsController /*NewsController*/: ODataController
 {
        //
        // GET: /News/
        private SchoolEntities entities = new SchoolEntities();

        private bool NewsExists(string key)
        {
            return entities.NewsAnnouncements.Any(p => p.Id == key);
        }


        //
        //
        // The parameterless version of the Get method returns the entire Products collection. The Get method with a key parameter looks up a product by its key (in this case, the Id property).
        //The [EnableQuery] attribute enables clients to modify the query, by using query options such as $filter, $sort, and $page
        [EnableQuery]
        public IQueryable<NewsAnnouncement> Get()

        {
            return entities.NewsAnnouncements;
        }
        [EnableQuery]
        public SingleResult<NewsAnnouncement> Get([FromODataUri] string key)
        {
            IQueryable<NewsAnnouncement> result = entities.NewsAnnouncements.Where(p => p.Id == key);
            return SingleResult.Create(result);
        }

        //To enable clients to add a new product to the database, add the following method to ProductsController.
        public async Task<IHttpActionResult> Post(NewsAnnouncement newsItem)
        {
            if (!ModelState.IsValid)
            {
                return BadRequest(ModelState);
            }
            entities.NewsAnnouncements.Add(newsItem);
            await Task.Delay(10);
            entities.SaveChanges();
            return Created(newsItem);
        }

        //PATCH performs a partial update. The client specifies just the properties to update.

        public async Task<IHttpActionResult> Patch([FromODataUri] string key, Delta<NewsAnnouncement> product)
        {
            if (!ModelState.IsValid)
            {
                return BadRequest(ModelState);
            }
            var entity = entities.NewsAnnouncements.Find(key);
            if (entity == null)
            {
                return NotFound();
            }
            product.Patch(entity);
            try
            {
                await Task.Delay(10);
                entities.SaveChanges();
            }
            catch (DbUpdateConcurrencyException)
            {
                if (!NewsExists(key))
                {
                    return NotFound();
                }
                else
                {
                    throw;
                }
            }
            return Updated(entity);
        }


        public async Task<IHttpActionResult> Put([FromODataUri] string key, NewsAnnouncement updateNews)
        {
            if (!ModelState.IsValid)
            {
                return BadRequest(ModelState);
            }
            if (key != updateNews.Id)
            {
                return BadRequest();
            }
            entities.Entry(updateNews).State = EntityState.Modified;
            try
            {
                await Task.Delay(10);
                entities.SaveChanges();
            }
            catch (DbUpdateConcurrencyException)
            {
                if (!NewsExists(key))
                {
                    return NotFound();
                }
                else
                {
                    throw;
                }
            }
            return Updated(updateNews);
        }

        // Notice that the controller overrides the Dispose method to dispose of the EntitiesContext.
        protected override void Dispose(bool disposing)
        {
            entities.Dispose();
            base.Dispose(disposing);
        }

    }

【讨论】：