以编程方式在 .NET EF Code First 中打开属性序列化

Question

我在 EF 6 上使用 CodeFirst 对我的数据进行了建模。 我正在构建一个 Web API，不同类型的客户端可以访问该 API，但取决于客户端的配置，他们应该看到或看不到模型的某些属性。

¿如何打开或关闭 [JsonIgnore] 或 [serialized]？是否可以设置一组特定的规则来执行此操作，例如验证器？

Answer 1

选项 1：使用自定义 ContractResolver

您可以创建自定义合同解析器并在创建响应时使用它：

public class TestContractResolver : DefaultContractResolver
{
    public string ExcludeProperties { get; set; }
    protected override IList<JsonProperty> CreateProperties(Type type,
                                           MemberSerialization memberSerialization)
    {
        if (!string.IsNullOrEmpty(ExcludeProperties))
            return base.CreateProperties(type, memberSerialization)
                        .Where(x => !ExcludeProperties.Split(',').Contains(x.PropertyName))
                        .ToList();

        return base.CreateProperties(type, memberSerialization);
    }
}

用法如下：

[HttpGet]
public HttpResponseMessage Test()
{
    var person = new Person() { Id = 1, FirstName = "x", LastName = "y", Age = 20 };
    string excludeProperties= "FirstName,Age";
    string result = JsonConvert.SerializeObject(person, Formatting.None,
                    new JsonSerializerSettings
                    {
                        ContractResolver = new TestContractResolver() 
                        { 
                            ExcludeProperties = excludeProperties
                        }
                    });
    var response = this.Request.CreateResponse(HttpStatusCode.OK);
    response.Content = new StringContent(result, Encoding.UTF8, "application/json");
    return response;
}

结果是：

{"Id":1,"LastName":"y"}

选项 2：使用字典

您可以忽略一个以逗号分隔的属性名称字符串，然后选择属性并将它们（名称和值）放入字典中并将它们用作结果：

[HttpGet]
public Dictionary<string, Object> Test()
{
    var person = new Person() { Id = 1, FirstName = "x", LastName = "y", Age = 20 };

    string excludeProperties = "FirstName,Age";
    var dictionary = new Dictionary<string, Object>();
    person.GetType().GetProperties()
          .Where(x => !excludeProperties.Split(',').Contains(x.Name)).ToList()
          .ForEach(p =>
          {
              var key = p.Name;
              var value = p.GetValue(person);
              dictionary.Add(key, value);
          });

    return dictionary;
}

结果是：

{"Id":1,"LastName":"y"}