C# webservice添加额外的节点

Posted 2023-04-12

【中文标题】C# webservice添加额外的节点

【英文标题】：C# webservice adding extra node

【发布时间】：2018-07-22 05:52:55

【问题描述】：

我正在编写一个 C# 服务来生成问题和答案。我的服务代码如下

public interface IExamService

    [OperationContract]
    [WebInvoke(Method = "GET",UriTemplate = "/ExamQs",RequestFormat = WebMessageFormat.Json,ResponseFormat = WebMessageFormat.Json,BodyStyle = WebMessageBodyStyle.Wrapped)]
    string GetExam();


public string GetExam()

    List<ExamClass> exam = new List<ExamClass>();
    for(int i=0; i < 4; i++)
    
        ExamClass ex = new ExamClass();
        ex.Question = "This is the Question no "+ i.ToString();
        ex.Answer1 = "This is Answer1 of Question " + i.ToString();
        ex.Answer2 = "This is Answer2 of Question " + i.ToString();
        ex.Answer3 = "This is Answer3 of Question " + i.ToString();
        ex.Answer4 = "This is Answer4 of Question " + i.ToString();
        ex.Correct = 1;
        exam.Add(ex);
    

    string json = JsonConvert.SerializeObject(exam);
    return json;

这是我用来从数据库中获取问题的考试课程。现在我正在对考试类进行硬编码。

namespace ExamService

public class ExamClass

    string question;
    string answer1;
    string answer2;
    string answer3;
    string answer4;
    Int32 correct;

    public string Question
    
        get
        
            return question;
        

        set
        
            question = value;
        
    

    public string Answer1
    
        get
        
            return answer1;
        

        set
        
            answer1 = value;
        
    

    public string Answer2
    
        get
        
            return answer2;
        

        set
        
            answer2 = value;
        
    

    public string Answer3
    
        get
        
            return answer3;
        

        set
        
            answer3 = value;
        
    

    public string Answer4
    
        get
        
            return answer4;
        

        set
        
            answer4 = value;
        
    

    public int Correct
    
        get
        
            return correct;
        

        set
        
            correct = value;
        
    

输出是

"GetExamResult":"[\"Question\":\"This is the Question no 0\",\"Answer1\":\"This is Answer1 of Question 0\",\"Answer2\":\"This is Answer2 of Question 0\",\"Answer3\":\"This is Answer3 of Question 0\",\"Answer4\":\"This is Answer4 of Question 0\",\"Correct\":1,\"Question\":\"This is the Question no 1\",\"Answer1\":\"This is Answer1 of Question 1\",\"Answer2\":\"This is Answer2 of Question 1\",\"Answer3\":\"This is Answer3 of Question 1\",\"Answer4\":\"This is Answer4 of Question 1\",\"Correct\":1,\"Question\":\"This is the Question no 2\",\"Answer1\":\"This is Answer1 of Question 2\",\"Answer2\":\"This is Answer2 of Question 2\",\"Answer3\":\"This is Answer3 of Question 2\",\"Answer4\":\"This is Answer4 of Question 2\",\"Correct\":1,\"Question\":\"This is the Question no 3\",\"Answer1\":\"This is Answer1 of Question 3\",\"Answer2\":\"This is Answer2 of Question 3\",\"Answer3\":\"This is Answer3 of Question 3\",\"Answer4\":\"This is Answer4 of Question 3\",\"Correct\":1,\"Question\":\"This is the Question no 4\",\"Answer1\":\"This is Answer1 of Question 4\",\"Answer2\":\"This is Answer2 of Question 4\",\"Answer3\":\"This is Answer3 of Question 4\",\"Answer4\":\"This is Answer4 of Question 4\",\"Correct\":1]"

我的问题是为什么 c# 在开始时添加“GetExamResult”以及如何摆脱它。谢谢。

【问题讨论】：

请发帖ExamClass

【参考方案1】：

为什么 c# 在开头添加 'GetExamResult' 以及如何摆脱它

这是由于BodyStyle = WebMessageBodyStyle.Wrapped。当 BodyStyle 被包装时，序列化程序将响应包装在额外的 JSON（或 XML）级别（请参阅 here）。

我知道这可能很麻烦并且并不总是需要，但在某些情况下，需要或需要 Wrapped 正文。当您返回裸值（作为int 或string）时就是这种情况，因为您无法将简单值映射到 JSON。实际上，您的代码就是这种情况。使用ResponseFormat = WebMessageFormat.Json，您不会告诉运行时您打算返回 JSON string，而是告诉运行时将您的返回值转换为有效的 JSON。 Ans 由于 string 不是有效的 JSON，因此需要将其包装在 JSON 中。

无论如何，有一种非常简单的方法可以让您实现您想要的（它甚至使您的代码更容易一些）。只需让您的 Web 方法直接返回一个 ExamClass 实例。您所要做的就是用DataContractAttribute 及其成员注释ExamClass 类（旁注：请不要在您的类名称后缀Class - 这是不好的风格） DataMemberAttribute

[DataContract]
public class ExamClass

    string question;
    string answer1;
    string answer2;
    string answer3;
    string answer4;
    Int32 correct;

    [DataMember]
    public string Question
    
        get
        
            return question;
        

        set
        
            question = value;
        
    

    [DataMember]
    public string Answer1
    
        get
        
            return answer1;
        

        set
        
            answer1 = value;
        
    

    // ...

然后你可以直接从IExamService返回一个ExamClass的对象

public interface IExamService

    [OperationContract]
    [WebInvoke(Method = "GET",
        UriTemplate = "/ExamQs",
        RequestFormat = WebMessageFormat.Json,
        ResponseFormat = WebMessageFormat.Json,
        BodyStyle = WebMessageBodyStyle.Bare)]
    ExamClass GetExam();

这更多地说明了 WPF 的使用方式。