Breeze Webapi控制器不支持通过DbSet错误查询 [英] Breeze webapi controller 'cannot support querying' over DbSet error

问题描述

我的设置与sample nuget中的微风样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，当我尝试通过WorkOrders操作执行查询时，我收到500-内部服务器错误，这是响应的有效负载：

{"$id":"1","$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)
   at System.Web.Http.QueryableAttribute.OnActionExecuted(HttpActionExecutedContext actionExecutedContext)
   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)
   at System.Web.Http.Tracing.Tracers.ActionFilterAttributeTracer.OnActionExecuted(HttpActionExecutedContext actionExecutedContext)
   at System.Web.Http.Filters.ActionFilterAttribute.<>c__DisplayClass2.<System.Web.Http.Filters.IActionFilter.ExecuteActionFilterAsync>b__0(HttpResponseMessage response)
   at System.Threading.Tasks.TaskHelpersExtensions.<>c__DisplayClass41`2.<Then>b__40(Task`1 t)
   at System.Threading.Tasks.TaskHelpersExtensions.ThenImpl[TTask,TOuterResult](TTask task, Func`2 continuation, CancellationToken cancellationToken, Boolean runSynchronously)"}

工作订单在上下文中设置为数据库：

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

我还尝试将其显式转换为IQueryable，没有任何更改：

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

唯一对我有效的是：

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

然而，这给我的客户端带来了另一个问题，如this问题所述。

推荐答案

这里只是猜测，但您可以尝试使用具有以下属性的最新微风(v0.82.1)吗？

[BreezeController]

而非这些

[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。

这篇关于Breeze Webapi控制器不支持通过DbSet错误查询的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！