Question

我有一个正常工作的HttpResponseMessage返回数据，我的问题是如何计算数据？

using (HttpClient httpClient = new HttpClient())
{
     httpClient.BaseAddress = new Uri("https://api.com/");
     httpClient.DefaultRequestHeaders.Accept.Clear();
     httpClient.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
     httpClient.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", token);
     HttpResponseMessage response = httpClient.GetAsync("v1/registrants/search?email=" + email).Result;
     return response.Content.ReadAsStringAsync().Result;
}

请帮助。

这是返回的内容：

{
  "links" : {
    "next" : null
  },
  "items" : [ ]
}

如果项目为空，则表示计数应为0。

这是当它不为空时返回的内容

{
    "links": {
        "next": null
    },
    "items": [
        {
            "registrantId": 31436518,
            "personalId": 38464352,
            "firstName": "FirstName",
            "lastName": "LastName",
            "email": "email@domain.com",
            "address": ", Stoney Creek, , 90210, ",
            "phone": "9053341529",
            "_links": {
                "self": "/registrants/31436518"
            }
        }
    ]
}

Answer 1

在继续之前安装Nuget Newtonsoft.Json。

1）将序列化的字符串响应反序列化为JObject

public async Task<JObject> FetchData()
{
    using (HttpClient httpClient = new HttpClient())
    {
         httpClient.BaseAddress = new Uri("https://api.com/");
         httpClient.DefaultRequestHeaders.Accept.Clear();
         httpClient.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
         httpClient.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", token);
         HttpResponseMessage response = httpClient.GetAsync("v1/registrants/search?email=" + email).Result;
         string response = await response.Content.ReadAsStringAsync();
         return JsonConvert.DeserializeObject<JObject>(response);
    }
}

2）在其上调用.Count()方法，如果不存在items，请使用safe-evaluation operator与null coalescing operator的组合进行后备。

public async Task<int> CalculateCount()
{
    JObject responseObject = await FetchData();
    return responseObject["items"]?.Count() ?? 0;
}

Answer 2

您可以使用JSON.net来解析JSON。

首先定义一个对结果进行建模的类：

class ResultModel
{
  public List<Item> items { get; set; }
}

然后调用JsonConvert.DeserializeObject<T>(string json)解析/映射结果：

using (HttpClient httpClient = new HttpClient())
{
   httpClient.BaseAddress = new Uri("https://api.com/");
   httpClient.DefaultRequestHeaders.Accept.Clear();
   httpClient.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
   httpClient.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", token);
   HttpResponseMessage response = httpClient.GetAsync("v1/registrants/search?email=" + email).Result;
   string json = response.Content.ReadAsStringAsync().Result;
   ResultModel result = JsonConvert.DeserializeObject<ResultModel>(json);
   int count = result.items.Count();
}

ASP.NET从HttpResponseMessage获取结果计数

2 个答案: