DataContractJsonSerializer通用列表，其中包含元素类型的子类型 [英] DataContractJsonSerializer generic list containing element type's subtypes

问题描述

我将使用 DataContractJsonSerializer 进行JSON序列化/反序列化。

I'm going to use DataContractJsonSerializer for JSON serialization/deserialization.

我有两种对象类型JSON数组，并希望将它们都反序列化为相应的对象类型。
具有以下类定义

I have two object types in the JSON array and want them both to be deserialized into corresponding object types. Having the following class defnitions

[DataContract]
public class Post {
    [DataMember(Name = "content")]
    public String Content { get; set; }
}

[DataContract]
public class User {
    [DataMember(Name = "user_name")]
    public String UserName { get; set; }
    [DataMember(Name = "email")]
    public String Email { get; set; }
}

[DataContract]
public class Container {
    [DataMember(Name="posts_and_objects")]
    public List<Object> PostsAndUsers { get; set; }
}

我如何检测到它们并将它们反序列化为相应的对象类型并存储在 PostsAndUsers 属性中？

how can I detect them and deserialize both into the corresponding object type and store in PostsAndUsers property?

推荐答案

如果您指定已知类型，则可以序列化和反序列化您的类Container，请尝试以下代码：

If you specific the known types you can serialize and deserialize your class Container, try this code:

protected static Stream GetStream<T>(T content)
{
    MemoryStream memoryStream = new MemoryStream();
    DataContractJsonSerializer serializer = new DataContractJsonSerializer(typeof(T), new []{typeof(Post), typeof(User)});
    serializer.WriteObject(memoryStream, content);
    memoryStream.Seek(0, SeekOrigin.Begin);
    return memoryStream;
}

protected static T GetObject<T>(Stream stream)
{
    DataContractJsonSerializer serializer = new DataContractJsonSerializer(typeof(T), new[] { typeof(Post), typeof(User) });
    return (T)serializer.ReadObject(stream);
}

static void Main(string[] args)
{
    var container = new Container {PostsAndUsers = new List<object>()};
    container.PostsAndUsers.Add(new Post{Content = "content1"});
    container.PostsAndUsers.Add(new User{UserName = "username1"});
    container.PostsAndUsers.Add(new Post { Content = "content2" });
    container.PostsAndUsers.Add(new User { UserName = "username2" });

    var stream = GetStream(container);
    var parsedContainer = GetObject<Container>(stream);

    foreach (var postsAndUser in parsedContainer.PostsAndUsers)
    {
        Post post;
        User user;
        if ((post = postsAndUser as Post) != null) 
        {
            // is post
        }
        else if ((user = postsAndUser as User) != null) 
        {
            // is user
        }
        else
        {
            throw new Exception("");
        }
    }
}

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