System.Text.Json API 有没有像 IContractResolver 这样的东西

Question

在新的System.Text.Json；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 迁移出去。

这是我要移动的类之一：

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;
}
}

Answer 1

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 个问题：

请试试这个：
我将其写为 System.Text.Json 的扩展以提供缺少的功能：https://github.com/dahomey-technologies/Dahomey.Json.

您会发现对编程对象映射的支持。

定义您自己的 IObjectMappingConvention 实现：

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 class:

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

通过在 JsonSerializerOptions 上调用命名空间 Dahomey.Json:

中定义的扩展方法 SetupExtensions 来设置 json 扩展

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

为class注册新的对象映射约定：

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

然后用常规 Sytem.Text.Json API:

序列化你的 class

Employee employee = new Employee
{
    Id = 12,
    FirstName = "John",
    LastName = "Doe",
    Email = "john.doe@acme.com"
};
        
string json = JsonSerializer.Serialize(employee, options);
// {"Id":12,"FirstName":"John","Email":"john.doe@acme.com"};

System.Text.Json API 有没有像 IContractResolver 这样的东西

System.Text.Json API is there something like IContractResolver

c#

serialization

.net-core

asp.net-core

system.text.json