我使用的是Json。将类序列化为JSON。
我的课程是这样的:
class Test1
{
[JsonProperty("id")]
public string ID { get; set; }
[JsonProperty("label")]
public string Label { get; set; }
[JsonProperty("url")]
public string URL { get; set; }
[JsonProperty("item")]
public List<Test2> Test2List { get; set; }
}
我想仅当Test2List为空时才向Test2List属性添加JsonIgnore()属性。如果它不是空的，那么我想包括它在我的json。
当前回答
在。net Core中，这就容易多了。在你的startup.cs中添加json选项，你可以在那里配置设置。
public void ConfigureServices(IServiceCollection services)
....
services.AddMvc().AddJsonOptions(options =>
{
options.SerializerSettings.NullValueHandling = NullValueHandling.Ignore;
});
其他回答
可以在他们的网站(http://james.newtonking.com/archive/2009/10/23/efficient-json-with-json-net-reducing-serialized-json-size.aspx)上的这个链接中看到，我支持使用[Default()]来指定默认值
摘自链接
public class Invoice
{
public string Company { get; set; }
public decimal Amount { get; set; }
// false is default value of bool
public bool Paid { get; set; }
// null is default value of nullable
public DateTime? PaidDate { get; set; }
// customize default values
[DefaultValue(30)]
public int FollowUpDays { get; set; }
[DefaultValue("")]
public string FollowUpEmailAddress { get; set; }
}
Invoice invoice = new Invoice
{
Company = "Acme Ltd.",
Amount = 50.0m,
Paid = false,
FollowUpDays = 30,
FollowUpEmailAddress = string.Empty,
PaidDate = null
};
string included = JsonConvert.SerializeObject(invoice,
Formatting.Indented,
new JsonSerializerSettings { });
// {
// "Company": "Acme Ltd.",
// "Amount": 50.0,
// "Paid": false,
// "PaidDate": null,
// "FollowUpDays": 30,
// "FollowUpEmailAddress": ""
// }
string ignored = JsonConvert.SerializeObject(invoice,
Formatting.Indented,
new JsonSerializerSettings { DefaultValueHandling = DefaultValueHandling.Ignore });
// {
// "Company": "Acme Ltd.",
// "Amount": 50.0
// }
与Json。网
public class Movie
{
public string Name { get; set; }
public string Description { get; set; }
public string Classification { get; set; }
public string Studio { get; set; }
public DateTime? ReleaseDate { get; set; }
public List<string> ReleaseCountries { get; set; }
}
Movie movie = new Movie();
movie.Name = "Bad Boys III";
movie.Description = "It's no Bad Boys";
string ignored = JsonConvert.SerializeObject(movie,
Formatting.Indented,
new JsonSerializerSettings { NullValueHandling = NullValueHandling.Ignore });
结果将是:
{
"Name": "Bad Boys III",
"Description": "It's no Bad Boys"
}
或者像这样设置。
services.AddMvc().AddJsonOptions(options =>
options.JsonSerializerOptions.IgnoreNullValues = true;
});
JSON。NET也尊重DataMemberAttribute上的EmitDefaultValue属性，以防你不想将newtonsoft特定的属性添加到你的模型中:
[DataMember(Name="property_name", EmitDefaultValue=false)]
你可以写:[JsonProperty("property_name"，DefaultValueHandling = DefaultValueHandling. ignore)]
它还负责使用默认值(不仅仅是null)不序列化属性。例如，它对枚举很有用。
