c# – Odata No NavigationLink工厂被发现

概述我目前正在使用一个mvc4 web api odata服务,我想返回用户列表中的用户列表.当我想得到用户我得到以下错误： 错误： <m:innererror><m:message>The 'ObjectContent`1' type failed to serialize the response body for content type 'application/json; charset 我目前正在使用一个mvc4 web API odata服务,我想返回用户列表中的用户列表.当我想得到用户我得到以下错误：

错误：

<m:innererror><m:message>The 'ObjectContent`1' type Failed to serialize the response body for content type 'application/Json; charset=utf-8'.</m:message><m:type>system.invalIDOperationException</m:type><m:stacktrace/><m:internalexception><m:message>No Navigationlink factory was found for the navigation property 'Languages' from entity type 'MvcWebrole1.Models.User' on entity set 'Users'. Try calling HasNavigationPropertylink on the EntitySetConfiguration. Parameter name: navigationProperty</m:message><m:type>System.ArgumentException</m:type><m:stacktrace>at System.Web.http.OData.Builder.EntitySetlinkBuilderAnnotation.BuildNavigationlink(EntityInstanceContext instanceContext,IEdmNavigationProperty navigationProperty,ODataMetadataLevel MetadataLevel) at System.Web.http.OData.Formatter.Serialization.ODataEntityTypeSerializer.WriteNavigationlinks(EntityInstanceContext context,ODataWriter writer,ODataSerializerContext writeContext) at System.Web.http.OData.Formatter.Serialization.ODataEntityTypeSerializer.WriteEntry(Object graph,IEnumerable`1 propertybag,ODataSerializerContext writeContext) at System.Web.http.OData.Formatter.Serialization.ODataEntityTypeSerializer.WriteObjectInline(Object graph,ODataSerializerContext writeContext) at System.Web.http.OData.Formatter.Serialization.OdatafeedSerializer.WriteFeed(Object graph,ODataSerializerContext writeContext) at System.Web.http.OData.Formatter.Serialization.OdatafeedSerializer.WriteObjectInline(Object graph,ODataSerializerContext writeContext) at System.Web.http.OData.Formatter.Serialization.OdatafeedSerializer.WriteObject(Object graph,ODataMessageWriter messageWriter,ODataSerializerContext writeContext) at System.Web.http.OData.Formatter.ODataMediaTypeFormatter.<>c__displayClassa.<WritetoStreamAsync>b__9() at System.Threading.Tasks.TaskHelpers.RunSynchronously(Action action,CancellationToken token)</m:stacktrace></m:internalexception></m:innererror>

我的用户看起来像这样：

public class User{    [Key]    public int UserID { get; set; }    public string Firstname { get; set; }    public string Lastname { get; set; }    public string Username { get; set; }    public string Password { get; set; }    public virtual ICollection<Language> Languages { get; set; }    public User()    {        Languages = new List<Language>();    }}

而我的UsersController for OData看起来像这样：

public class UsersController : EntitySetController<User,int>{    WorldChatContext db = new WorldChatContext();    public overrIDe Iqueryable<User> Get()    {        return db.Users.Asqueryable();    }    protected overrIDe User GetEntityByKey(int key)    {        return db.Users.FirstOrDefault(p => p.UserID == key);    }    public overrIDe httpResponseMessage Post(User entity)    {        db.Users.Add(entity);        db.SaveChanges();        return base.Post(entity);    }}

我正在呼叫我在路由中设置的以下url：http://127.0.0.1:81/odata/如果我在我的用户模型中注释了导航属性,则可以使用它.

我究竟做错了什么？我已经尝试将[Serializable,KNownType(typeof(Language))]放在我的用户类之上,但由于某种原因我不能使用KNownType.我如何使我的OData与此导航属性一起使用？

解决方法 您缺少为语言设置的实体.导航属性指向实体,必须绑定到实体集.在您的模型构建器代码中,添加此行来解决问题.

builder.EntitySet<Language>("languages");

这样做是创建实体集“语言”.约定模型构建器将导航属性绑定到实体集合(如果有的话).因此,导航属性实体类型用户的语言将被绑定到实体集语言.

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