System.Text.Json API 是否有类似 IContractResolver 的东西 [英] System.Text.Json API is there something like IContractResolver

问题描述

在新的 System.Text.Json 中；命名空间是否有类似 IContractResolver 的东西，我正在尝试将我的项目从 Newtonsoft 迁移.

In the new System.Text.Json; namespace is there something like IContractResolver i am trying to migrate my project away from Newtonsoft.

这是我想转移的课程之一:

This is one of the classes i am trying to move:

public class SelectiveSerializer : DefaultContractResolver
{
private readonly string[] fields;

public SelectiveSerializer(string fields)
{
  var fieldColl = fields.Split(',');
  this.fields = fieldColl
      .Select(f => f.ToLower().Trim())
      .ToArray();
}

protected override JsonProperty CreateProperty(MemberInfo member, MemberSerialization memberSerialization)
{
  var property = base.CreateProperty(member, memberSerialization);
  property.ShouldSerialize = o => fields.Contains(member.Name.ToLower());

  return property;
}
}

推荐答案

System.Text.Json 中的等效类型 -- JsonClassInfo 和 JsonPropertyInfo -- 是内部的.有一个开放的增强相当于 System.Text.Json 中的 DefaultContractResolver #31257要求公共等价物.– dbc 11 月 25 日 19:11

The equivalent types in System.Text.Json -- JsonClassInfo and JsonPropertyInfo -- are internal. There is an open enhancement Equivalent of DefaultContractResolver in System.Text.Json #31257 asking for a public equivalent. – dbc Nov 25 at 19:11

Github 问题:

• 开放 System.Text.Json 的元数据基础结构 #34456
• 相当于 System.Text.Json 中的 DefaultContractResolver.CreateProperties 覆盖 #60518
• 相当于 System.Text.Json 中的 DefaultContractResolver #31257

请试试这个:
我将其作为 System.Text.Json 的扩展编写，以提供缺失的功能:https://github.com/dahomey-technologies/Dahomey.Json.

您会发现对编程对象映射的支持.

You will find support for programmatic object mapping.

定义您自己的 IObjectMappingConvention 实现:

Define your own implementation of IObjectMappingConvention:

public class SelectiveSerializer : IObjectMappingConvention
{
    private readonly IObjectMappingConvention defaultObjectMappingConvention = new DefaultObjectMappingConvention();
    private readonly string[] fields;

    public SelectiveSerializer(string fields)
    {
        var fieldColl = fields.Split(',');
        this.fields = fieldColl
            .Select(f => f.ToLower().Trim())
            .ToArray();
    }

    public void Apply<T>(JsonSerializerOptions options, ObjectMapping<T> objectMapping) where T : class
    {
        defaultObjectMappingConvention.Apply<T>(options, objectMapping);
        foreach (IMemberMapping memberMapping in objectMapping.MemberMappings)
        {
            if (memberMapping is MemberMapping<T> member)
            {
                member.SetShouldSerializeMethod(o => fields.Contains(member.MemberName.ToLower()));
            }
        }
    }
}

定义你的类:

public class Employee
{
    public int Id { get; set; }
    public string FirstName { get; set; }
    public string LastName { get; set; }
    public string Email { get; set; }
}

通过调用命名空间 Dahomey.Json 中定义的扩展方法 SetupExtensions 调用 JsonSerializerOptions 来设置 json 扩展:

Setup json extensions by calling on JsonSerializerOptions the extension method SetupExtensions defined in the namespace Dahomey.Json:

JsonSerializerOptions options = new JsonSerializerOptions();
options.SetupExtensions();

为类注册新的对象映射约定:

Register the new object mapping convention for the class:

options.GetObjectMappingConventionRegistry().RegisterConvention(
    typeof(Employee), new SelectiveSerializer("FirstName,Email,Id"));

然后使用常规 Sytem.Text.Json API 序列化您的类:

Then serialize your class with the regular Sytem.Text.Json API:

Employee employee = new Employee
{
    Id = 12,
    FirstName = "John",
    LastName = "Doe",
    Email = "[e-mail]"
};
        
string json = JsonSerializer.Serialize(employee, options);
// {"Id":12,"FirstName":"John","Email":"[e-mail]"};

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