使用可選的複雜類型動作參數爲POST的Web API

Question

我想寫用以下原型的API：

[HttpPost] 
public ApplicationStatus appLogIn(string id, UserCredentials userCredentials = null) 

但是，當我對這個API的請求，帶或不帶userCredentials，我得到響應代碼以下錯誤作爲500

{ 
    "Message": "An error has occurred.", 
    "ExceptionMessage": "Optional parameter 'userCredentials' is not supported by 'FormatterParameterBinding'.", 
    "ExceptionType": "System.InvalidOperationException", 
    "StackTrace": null 
} 

如果我不作userCredentials可選，一切工作正常。所述userCredential定義如下：

public class UserCredentials 
{ 
    public string password { get; set; } 
    public string username { get; set; } 
} 

Answer 1

嘗試改變API定義：

[HttpPost] 
public ApplicationStatus appLogIn(string id, UserCredentials userCredentials) 

作爲UserCredentials是引用類型，如果客戶端不提供將被設置爲空

的值