Question

我有一个行为路由，返回非实体集合。

ActionConfiguration previewInvoices = this.EntityType.Collection.Action("PreviewInvoices");
previewInvoices.ReturnsCollection<InvoicePreviewComponent>();

现在当我查询以获得结果时，我使用$take=20来控制通过javascript进行分页。但是，它不会像使用$inlinecount=allpages的实体集一样返回计数。

我一直在做的一个解决方案是将行改为：

ActionConfiguration previewInvoices = this.EntityType.Collection.Action("PreviewInvoices");
previewInvoices.ReturnsCollectionFromCollection<InvoicePreviewComponent>("InvoicePreviewComponent");

然而，这会在$metadata中生成ghost实体集，我用它来生成javascript模型和请求。不理想，最终不能正确地将其注释为实体集。

如何修改响应JSON格式化程序以按要求提供计数？

Answer 1

非实体集合的计数值不会被序列化到响应正文中。

但您可以通过以下代码获取计数值：

response.RequestMessage.ODataProperties().TotalCount

（注意：ODataProperties（）是静态类中的扩展方法 System.Web.Http.OData.Extensions.HttpRequestMessageExtensions）

Answer 2

这也可以通过动作过滤器来实现：

/// <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&& actionExecutedContext.Response.StatusCode==System.Net.HttpStatusCode.OK)
        {                
            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;               
        }           
    }
}

自定义PageResult类是：

public class PageResult<T>
{      
    public long? TotalCount { get; set; }
    public T Items { get; set; }
}

用法：

[PagedResult]
[EnableQuery()]

返回非实体集集合的OData计数

2 个答案: