Items count in OData v4 WebAPI response

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

Answer 1

This can also be achieved by an action filter:

/// 

/// 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.
/// 
public class PagedResultAttribute: ActionFilterAttribute
{
    /// 

    /// 
    /// 
    /// 
    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().Result;
            var count = actionExecutedContext.Response.RequestMessage.ODataProperties().TotalCount;
            var res = new PageResult() {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
{      
    public long? TotalCount { get; set; }
    public T Items { get; set; }
}

Usage:

[PagedResult]
[EnableQuery()]