Breeze webapi 控制器“无法支持查询”超过 DbSet 错误

Question

我的设置与 sample nuget 中的微风示例应用程序非常相似。这是我的 api 控制器的代码：

[JsonFormatter, ODataActionFilter]
public class WorkOrdersController : ApiController
{
    readonly EFContextProvider<WorkOrdersContext> _contextProvider =
        new EFContextProvider<WorkOrdersContext>();

    public WorkOrdersController()
    {
        // I was thinking this may be the cause of the issue
        this._contextProvider.Context.Configuration.ProxyCreationEnabled = false;
    }

    [HttpGet]
    public string Metadata()
    {
        return _contextProvider.Metadata();
    }

    [HttpPost]
    public SaveResult SaveChanges(JObject saveBundle)
    {
        return _contextProvider.SaveChanges(saveBundle);
    }

    [HttpGet]
    public IQueryable<WorkOrder> WorkOrders()
    {
        return _contextProvider.Context.WorkOrders;
    }

}

我遇到的问题是，当我尝试对 WorkOrders 操作执行查询时，我得到 500 - Internal server error，这是响应的负载：

{"$id":"1","$type":"System.Web.Http.HttpError, System.Web.Http","Message":"An error has occurred.","ExceptionMessage":"The action 'WorkOrders' on controller 'WorkOrders' with return type 'System.Collections.Generic.List`1[[WorkOrders.Domain.Models.WorkOrder, WorkOrders.Domain, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]]' cannot support querying. Ensure the type of the returned content is IEnumerable, IQueryable, or a generic form of either interface.","ExceptionType":"System.InvalidOperationException","StackTrace":"   at System.Web.Http.QueryableAttribute.ValidateReturnType(Type responseContentType, HttpActionDescriptor actionDescriptor)\r\n   at System.Web.Http.QueryableAttribute.OnActionExecuted(HttpActionExecutedContext actionExecutedContext)\r\n   at System.Web.Http.Tracing.ITraceWriterExtensions.TraceBeginEnd(ITraceWriter traceWriter, HttpRequestMessage request, String category, TraceLevel level, String operatorName, String operationName, Action`1 beginTrace, Action execute, Action`1 endTrace, Action`1 errorTrace)\r\n   at System.Web.Http.Tracing.Tracers.ActionFilterAttributeTracer.OnActionExecuted(HttpActionExecutedContext actionExecutedContext)\r\n   at System.Web.Http.Filters.ActionFilterAttribute.<>c__DisplayClass2.<System.Web.Http.Filters.IActionFilter.ExecuteActionFilterAsync>b__0(HttpResponseMessage response)\r\n   at System.Threading.Tasks.TaskHelpersExtensions.<>c__DisplayClass41`2.<Then>b__40(Task`1 t)\r\n   at System.Threading.Tasks.TaskHelpersExtensions.ThenImpl[TTask,TOuterResult](TTask task, Func`2 continuation, CancellationToken cancellationToken, Boolean runSynchronously)"}

WorkOrders 是上下文中的 Dbset：

public DbSet<WorkOrder> WorkOrders { get; set; }

我也尝试过将其显式转换为 IQueryable，但没有任何变化：

[HttpGet]
public IQueryable<WorkOrder> WorkOrders()
{
    return (IQueryable<WorkOrder>)_contextProvider.Context.WorkOrders;
}

唯一对我有用的是：

[HttpGet] 公共 IEnumerable WorkOrders() { 返回 _contextProvider.Context.WorkOrders.AsEnumerable(); }

然而，这在客户端给我带来了另一个问题，如this 问题中所述。

Answer 1

这里只是一个猜测，但您可以尝试使用具有以下属性的最新微风（v 0.82.1）。

[微风控制器]

而不是这些

[JsonFormatter, ODataActionFilter]

新的 [BreezeController] 属性完全替代了其他两个属性并避免了其他一些问题。