asp.net - 使用返回 XML 的 Recurly Rest API 时出现 WebAPI 序列化问题

Question

我是 ASP.Net Web API 的新手。我正在尝试与基于 Recurly REST 的 API 进行交互，并且在 ReadAsAsync 调用期间出现如下错误，我相信这是我尝试序列化响应的关键。

{"Error in line 1 position 73. Expecting element 'account' from namespace 'http://schemas.datacontract.org/2004/07/RecurlyWebApi.Recurly'.. Encountered 'Element'  with name 'account', namespace ''. "}

这是我的 HttpClient 实现，为简洁起见进行了简化:

  public class RecurlyClient
  {
    readonly HttpClient client = new HttpClient();

    public RecurlyClient()
    {
      var config = (RecurlySection)ConfigurationManager.GetSection("recurly");

      client.BaseAddress = new Uri(string.Format("https://{0}.recurly.com/v2/", config.Subdomain));

      // Add the authentication header
      client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Basic", Convert.ToBase64String(Encoding.ASCII.GetBytes(config.ApiKey)));

      // Add an Accept header for XML format.
      client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/xml"));
    }

    public T Get<T>(string id)
    {
      var accounts = default(T);

      // Make the request and get the response from the service
      HttpResponseMessage response = client.GetAsync(string.Concat("accounts/", id)).Result;  // Blocking call!

      if (response.IsSuccessStatusCode)
      {
        // Parse the response body. Blocking!
        accounts = response.Content.ReadAsAsync<T>().Result;
      }

      return accounts;
    }
  }

这是我的模型:

  [XmlRoot("account")]
  public class Account
  {
    [XmlAttribute("href")]
    public string Href { get; set; }

    [XmlElement("account_code")]
    public string AccountCode { get; set; }

    [XmlElement("state")]
    public AccountState State { get; set; }

    [XmlElement("username")]
    public string Username { get; set; }

    [XmlElement("email")]
    public string Email { get; set; }

    [XmlElement("first_name")]
    public string FirstName { get; set; }

    [XmlElement("last_name")]
    public string LastName { get; set; }

    [XmlElement("company_name")]
    public string Company { get; set; }

    [XmlElement("accept_language")]
    public string LanguageCode { get; set; }

    [XmlElement("hosted_login_token")]
    public string HostedLoginToken { get; set; }

    [XmlElement("created_at")]
    public DateTime CreatedDate { get; set; }

    [XmlElement("address")]
    public Address Address { get; set; }
  }

以及来自服务的 XML 响应示例:

<account href="https://mysubdomain.recurly.com/v2/accounts/SDTEST01">
  <adjustments href="https://mysubdomain.recurly.com/v2/accounts/SDTEST01/adjustments"/>
  <invoices href="https://mysubdomain.recurly.com/v2/accounts/SDTEST01/invoices"/>
  <subscriptions href="https://mysubdomain.recurly.com/v2/accounts/SDTEST01/subscriptions"/>
  <transactions href="https://mysubdomain.recurly.com/v2/accounts/SDTEST01/transactions"/>
  <account_code>SDTEST01</account_code>
  <state>active</state>
  <username>myusername</username>
  <email>simon@example.co.uk</email>
  <first_name>First name</first_name>
  <last_name>Last name</last_name>
  <company_name>My Company Name</company_name>
  <vat_number nil="nil"></vat_number>
  <address>
    <address1>My Address Line 1/address1>
    <address2>My Address Line 2</address2>
    <city>My City</city>
    <state>My State</state>
    <zip>PL7 1AB</zip>
    <country>GB</country>
    <phone>0123456789</phone>
  </address>
  <accept_language nil="nil"></accept_language>
  <hosted_login_token>***</hosted_login_token>
  <created_at type="datetime">2013-08-22T15:58:17Z</created_at>
</account>

Answer 1

我认为问题是因为默认情况下 DataContractSerializer 用于反序列化 XML，并且默认情况下 DataContractSerializer 使用命名空间 http://schemas.datacontract.org/2004/07/Clr.Namespace 的命名空间. (在这种情况下， Clr.Namepace 是 RecurlyWebApi.Recurly。)

因为您的 XML 具有属性，所以您需要使用 XmlSerializer 而不是 DataContractSerializer，并且您准备这样做是因为您的帐户类是用 Xml* 属性修饰的。但是，您必须使用使用 XmlSerializer 的 XmlMediaTypeFormatter。您可以按照 this page 中所述，通过在全局 XMLFormatter 上设置标志来实现此目的。 :

var xml = GlobalConfiguration.Configuration.Formatters.XmlFormatter;
xml.UseXmlSerializer = true;

或者通过将 MediaTypeFormatter 作为参数提供给 ReadAsAsync 调用:

var xmlFormatter = GlobalConfiguration.Configuration.Formatters.XmlFormatter;
xmlFormatter.UseXmlSerializer = true;
accounts = response.ReadAsAsync<T>(xmlFormatter).Result

不是 100% 确定这一点，因为这并不能解释为什么错误消息中的第一个“帐户”是小写的 - DataContractSerializer 应该忽略 XmlRoot 属性。