Items count in OData v4 WebAPI response - count

Question

How to return number of items in OData v4 HTTP response?
I need this number to pagination, so it should be number of items after filtering, but before 'skip' and 'top'.
I already tried passing '$inlinecount=allpages' and '$count=true' parameters in query options in url (https://damienbod.wordpress.com/2014/06/13/web-api-and-odata-v4-queries-functions-and-attribute-routing-part-2/ - "Example of $count"), but my responses from WebAPI always have only query results (collection) - whole response looks like:
[
{
"Name":"name1",
"age":5
},
{
"Name":"name2",
"age":15
}
]
There is nothing like "odata.count" in the response.
I also tried returning PageResult instead of IQueryable in my WebAPI controller action (like described here: http://www.asp.net/web-api/overview/odata-support-in-aspnet-web-api/supporting-odata-query-options#server-paging), but Request.GetInlineCount() is deprecated and its value is always null.
Any ideas?
[Update] I just found the same problem here: WebApi with Odata NextPage and Count not appearing in the JSON response and I removed [EnableQuery] attribute and now my response looks like:
{
"Items":
[
{
"Name":"name1",
"age":5
},
{
"Name":"name2",
"age":15
}
],
"NextPageLink":null,
"Count":null
}
But still "Count" is always null. :(
Edit: After debugging and searching for count value in Request properties in my controller, I found out that correct Count value is in property named "System.Web.OData.TotalCount". So right now I exctract this value from that request property and my controller looks like that:
public PageResult<People> Get(ODataQueryOptions<People> queryOptions)
{
var query = _context.People.OrderBy(x => x.SomeProperty);
var queryResults = (IQueryable<People>)queryOptions.ApplyTo(query);
long cnt = 0;
if (queryOptions.Count != null)
cnt = long.Parse(Request.Properties["System.Web.OData.TotalCount"].ToString());
return new PageResult<People>(queryResults, null, cnt);
}
And it works fine, but I still don't know why I have to use workarounds like that.

Answer 1

For future reference (OData v4):
First of all $inlinecount it's not supported in OData v4 so you should use $count=true instead.
Second, if you have a normal ApiController and you return a type like IQueryable<T> this is the way you can attach a count property to the returned result:
using System.Web.OData;
using System.Web.OData.Query;
using System.Web.OData.Extensions;
//[EnableQuery] // -> If you enable globally queries does not require this decorator!
public IHttpActionResult Get(ODataQueryOptions<People> queryOptions)
{
var query = _peopleService.GetAllAsQueryable(); //Abstracted from the implementation of db access. Just returns IQueryable<People>
var queryResults = (IQueryable<People>)queryOptions.ApplyTo(query);
return Ok(new PageResult<People>(queryResults, Request.ODataProperties().NextLink, Request.ODataProperties().TotalCount));
}
Note:
OData functionality does not supported by ApiControllers so you
cannot have things like count or $metadata. If you choose to
use simple ApiController the way above is the one you should use
to return a count property.
For a full support of OData functionality you should implement a ODataController the following way:
PeopleController.cs
using System.Web.OData;
using System.Web.OData.Query;
public class PeopleController : ODataController
{
[EnableQuery(PageSize = 10, AllowedQueryOptions = AllowedQueryOptions.All)]
public IHttpActionResult Get()
{
var res = _peopleService.GetAllAsQueryable();
return Ok(res);
}
}
App_Start \ WebApiConfig.cs
public static void ConfigureOData(HttpConfiguration config)
{
//OData Models
config.MapODataServiceRoute(routeName: "odata", routePrefix: null, model: GetEdmModel(), batchHandler: new DefaultODataBatchHandler(GlobalConfiguration.DefaultServer));
config.EnsureInitialized();
}
private static IEdmModel GetEdmModel()
{
var builder = new ODataConventionModelBuilder
{
Namespace = "Api",
ContainerName = "DefaultContainer"
};
builder.EntitySet<People>("People").EntityType.HasKey(item => item.Id); //I suppose the returning list have a primary key property(feel free to replace the Id key with your key like email or whatever)
var edmModel = builder.GetEdmModel();
return edmModel;
}
Then you access your OData Api this way (example):
encoded uri:
http://localhost:<portnumber>/People/?%24count=true&%24skip=1&%24top=3
decoded:
http://localhost:<portnumber>/People/?$count=true&$skip=1&$top=3
References:
How to Use Web API OData to Build an OData V4 Service without Entity Framework
Web API OData V4 Pitfalls
Create an OData v4 Endpoint Using ASP.NET Web API 2.2

Answer 2

This can also be achieved by an action filter:
/// <summary>
/// Use this attribute whenever total number of records needs to be returned in the response in order to perform paging related operations at client side.
/// </summary>
public class PagedResultAttribute: ActionFilterAttribute
{
/// <summary>
///
/// </summary>
/// <param name="actionExecutedContext"></param>
public override void OnActionExecuted(HttpActionExecutedContext actionExecutedContext)
{
base.OnActionExecuted(actionExecutedContext);
if (actionExecutedContext.Response != null)
{
dynamic responseContent=null;
if (actionExecutedContext.Response.Content != null)
responseContent = actionExecutedContext.Response.Content.ReadAsAsync<dynamic>().Result;
var count = actionExecutedContext.Response.RequestMessage.ODataProperties().TotalCount;
var res = new PageResult<dynamic>() {TotalCount=count,Items= responseContent };
HttpResponseMessage message = new HttpResponseMessage();
message.StatusCode = actionExecutedContext.Response.StatusCode;
var strMessage = new StringContent(JsonConvert.SerializeObject(res), Encoding.UTF8, "application/json");
message.Content = strMessage;
actionExecutedContext.Response = message;
}
}
}
And the custom PageResult class is:
public class PageResult<T>
{
public long? TotalCount { get; set; }
public T Items { get; set; }
}
Usage:
[PagedResult]
[EnableQuery()]

Answer 3

Will you please take a look at the sample service TripPin web api implementation at https://github.com/OData/ODataSamples/blob/master/Scenarios/TripPin. You can follow the code in Airports controller and the service with the code http://services.odata.org/TripPinWebApiService/Airports?$count=true can return the count correctly.

Answer 4

That's what I am using with oData v4:
Request.ODataProperties().NextLink,
Request.ODataProperties().TotalCount

Answer 5

If you are using OData conventional routing, $odata.count is not returned when your routes are not known to odata. Add 'app.UseODataRouteDebug();' to your ConfigureServices-method and then invoke 'https://localhost:5001/$odata'. If your route is not in the OData-route table, your route is not known to OData and you are not using correct naming conventions for your controller and EDM-type to be included in OData conventional routing.