Using PageResult in a base ApiController returns a System.ArgumentNullException

Question

Im trying to write a generic PageResultthat I have added to a base controller.

    [EnableQuery]
    [HttpGet]
    [Route(""]
    public virtual PageResult<TListModel> Get(ODataQueryOptions<TListModel> options)
    {
        ODataQuerySettings settings = new ODataQuerySettings()
        {
            PageSize = 25,
        };

        IQueryable results = options.ApplyTo(DomainService.GetQueryable(), settings);
        var items = results as IQueryable<TListModel>;
      // return new PageResult<TListModel>(items, Request.ODataProperties().NextLink,DomainService.GetQueryable().Count());
        return new PageResult<TListModel>(items, Request.ODataProperties().NextLink, Request.ODataProperties().TotalCount);

    }

Now when I try call the api endpoint

/endpoint?$select=Title

I get an error

Value cannot be null.\ \ Parameter name: source

If I remove the ?$select=TitleI can call the api and the results are returned.

Is there something else I should be doing to enable this? The parameter name source....I have no idea what this is?

The full stacktrace

" at System.Linq.Queryable.Count[TSource](IQueryable1 source)\ \ at Api.EndPoints.BaseController5.Get(ODataQueryOptions1 options) in e:\\@Source\\Web\\Api\\.EndPoints\\BaseController.cs:line 62\ \ at lambda_method(Closure , Object , Object[] )\ \ at System.Web.Http.Controllers.ReflectedHttpActionDescriptor.ActionExecutor.<>c__DisplayClass10.<GetExecutor>b__9(Object instance, Object[] methodParameters)\ \ at System.Web.Http.Controllers.ReflectedHttpActionDescriptor.ActionExecutor.Execute(Object instance, Object[] arguments)\ \ at System.Web.Http.Controllers.ReflectedHttpActionDescriptor.ExecuteAsync(HttpControllerContext controllerContext, IDictionary2 arguments, CancellationToken cancellationToken)\ \ --- End of stack trace from previous location where exception was thrown ---\ \ at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)\ \ at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)\ \ at System.Runtime.CompilerServices.TaskAwaiter1.GetResult()\ \ at System.Web.Http.Controllers.ApiControllerActionInvoker.<InvokeActionAsyncCore>d__0.MoveNext()\ \ --- End of stack trace from previous location where exception was thrown ---\ \ at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)\ \ at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)\ \ at System.Runtime.CompilerServices.TaskAwaiter1.GetResult()\ \ at System.Web.Http.Filters.ActionFilterAttribute.d__5.MoveNext()\ \ --- End of stack trace from previous location where exception was thrown ---\ \ at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()\ \ at System.Web.Http.Filters.ActionFilterAttribute.d__5.MoveNext()\ \ --- End of stack trace from previous location where exception was thrown ---\ \ at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)\ \ at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)\ \ at System.Runtime.CompilerServices.TaskAwaiter1.GetResult()\ \ at System.Web.Http.Filters.ActionFilterAttribute.<ExecuteActionFilterAsyncCore>d__0.MoveNext()\ \ --- End of stack trace from previous location where exception was thrown ---\ \ at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)\ \ at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)\ \ at System.Runtime.CompilerServices.TaskAwaiter1.GetResult()\ \ at System.Web.Http.Controllers.ActionFilterResult.d__2.MoveNext()\ \ --- End of stack trace from previous location where exception was thrown ---\ \ at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)\ \ at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)\ \ at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult()\ \ at System.Web.Http.Dispatcher.HttpControllerDispatcher.d__1.MoveNext()"

This is because after ApplyTo method, results is not of type IQueryable<TListModel>, but a partial project collection of TListModel. — Karata

Jon Elliott Jon Elliott · Accepted Answer · 2015-06-22T11:26:18

I upgraded my solution to the latest Web API version and this is marked obolete, but works.

    [HttpGet, Route("Get")]
    public PageResult<DiplomateModel> Get(int legalValue, string area =                                                     null, int? pageSize = 20,ODataQueryOptions<Model> options = null)
    {
        try
        {
            var ret = GetUsers(legalValue, area);
            var settings = new ODataQuerySettings
            {
                PageSize = pageSize
            };
            IQueryable results = options.ApplyTo(ret, settings);
            var uri = Request.GetNextPageLink();
            long? inLineCount = Request.GetInlineCount();
            var response = new PageResult<DiplomateModel>(results as IEnumerable<Model>,uri,inLineCount);
            return response;
        }
        catch (Exception ex)
        {
            LogError(ex);
            return null;
        }
    }

Using PageResult in a base ApiController returns a System.ArgumentNullException

2 Answers