Question

此时任何建议都会受到赞赏。

我在MVC控制器中有一个简单的方法。

public IHttpActionResult GetCrudeAssessmentPrices(Int32? sellerid, DateTime? pdate, DateTime? pdateend)
    {
        var data = (dynamic)null;
        data = db.CrudeAssessmentPrices.Select(i => new { sellerid, i.Price, i.Assessment, i.PriceDate }).Where(r => r.PriceDate >= pdate).Where(r => r.PriceDate <= pdateend).OrderBy(a => a.Assessment).ThenBy(b => b.PriceDate).ToList();

        data = Json(data);
        return data;

    }

此方法在浏览器中的视图时返回以下内容：

[{"sellerid":95,"Price":47.14000,"Assessment":"Argus: ANS","PriceDate":"2015-10-01T00:00:00"},{"sellerid":95,"Price":49.02500,"Assessment":"Argus: ANS","PriceDate":"2015-10-01T00:00:00"}]

在控制台应用程序中，我有这个：

using System;
using System.Threading.Tasks;

using System.Net.Http;
using System.Net.Http.Headers;

namespace ConsumeJson
{
class AssessmentPrice
{
    public int sellerid { get; set; }
    public double Price { get; set; }
    public string Assessment { get; set; }

    public DateTime PriceDate { get; set; }
}

class Program
{
    static void Main()
    {
        RunAsync().Wait();
    }

    static async Task RunAsync()
    {
        using (var client = new HttpClient())
        {
            client.BaseAddress = new Uri("http://localhost:49467/");
            client.DefaultRequestHeaders.Accept.Clear();
            client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));

            // HTTP GET
            try
            {
                HttpResponseMessage response = await client.GetAsync("api/CrudeAssessmentPrices?sellerid=95&pdate=10/1/2015&pdateend=10/1/2015");
                response.EnsureSuccessStatusCode();

                if (response.IsSuccessStatusCode)
                {
                    AssessmentPrice assessmentprice = await response.Content.ReadAsAsync<AssessmentPrice>();
                    Console.WriteLine("{0}\t${1}\t{2}\t{3}", assessmentprice.sellerid, assessmentprice.Price, assessmentprice.Assessment, assessmentprice.PriceDate);
                }
            }
            catch (HttpRequestException e)
            {
                // Handle exception.
            }
        }
    }
}

}

运行控制台应用程序从api返回响应对象，但content属性显示标题，并且它有一个长度，但没有内容。产生以下错误：

   ***Message=Cannot deserialize the current JSON array (e.g. [1,2,3]) into     type 'ConsumeJson.AssessmentPrice' because the type requires a JSON object (e.g.     {"name":"value"}) to deserialize correctly.
To fix this error either change the JSON to a JSON object (e.g.     {"name":"value"}) or change the deserialized type to an array or a type that     implements a collection interface (e.g. ICollection, IList) like List<T> that     can be deserialized from a JSON array. JsonArrayAttribute can also be added to     the type to force it to deserialize from a JSON array.
Path '', line 1, position 1.
       Source=Newtonsoft.Json***

Answer 1

您的服务正在返回一组JSON对象，但您的控制台应用程序需要一个JSON对象。您可以返回包含该数组的JSON对象：{"arrayOfObjects" : [{"one"}, {"two"}]}或告诉它期望数组。

如何使用返回Json的Web API？

1 个答案: