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
对于System.Text.Json和.NET Core 3.0，这对我来说是可行的:
var jsonSerializerOptions = new JsonSerializerOptions()
{
IgnoreNullValues = true
};
var myJson = JsonSerializer.Serialize(myObject, jsonSerializerOptions );
其他回答
在我的情况下，使用。net 6这是解决方案:
[JsonIgnore(Condition = JsonIgnoreCondition.WhenWritingNull)]
更多信息请点击这里。
To expound slightly on GlennG's very helpful answer (translating the syntax from C# to VB.Net is not always "obvious") you can also decorate individual class properties to manage how null values are handled. If you do this don't use the global JsonSerializerSettings from GlennG's suggestion, otherwise it will override the individual decorations. This comes in handy if you want a null item to appear in the JSON so the consumer doesn't have to do any special handling. If, for example, the consumer needs to know an array of optional items is normally available, but is currently empty... The decoration in the property declaration looks like this:
<JsonPropertyAttribute("MyProperty", DefaultValueHandling:=NullValueHandling.Include)> Public Property MyProperty As New List(of String)
For those properties you don't want to have appear at all in the JSON change :=NullValueHandling.Include to :=NullValueHandling.Ignore. By the way - I've found that you can decorate a property for both XML and JSON serialization just fine (just put them right next to each other). This gives me the option to call the XML serializer in dotnet or the NewtonSoft serializer at will - both work side-by-side and my customers have the option to work with XML or JSON. This is slick as snot on a doorknob since I have customers that require both!
或者像这样设置。
services.AddMvc().AddJsonOptions(options =>
options.JsonSerializerOptions.IgnoreNullValues = true;
});
.Net 6 - 在Program.cs中添加代码。这将忽略类或记录属性，如果它是空的。
using System.Text.Json.Serialization;
var builder = WebApplication.CreateBuilder(args);
builder.Services.AddControllers()
.AddJsonOptions(opts =>
{
var enumConverter = new JsonStringEnumConverter();
opts.JsonSerializerOptions.Converters.Add(enumConverter);
opts.JsonSerializerOptions.DefaultIgnoreCondition = JsonIgnoreCondition.WhenWritingDefault | JsonIgnoreCondition.WhenWritingNull;
});
@Mrchief / @amit的答案的改编，但适用于使用VB的人
Dim JSONOut As String = JsonConvert.SerializeObject(
myContainerObject,
New JsonSerializerSettings With {
.NullValueHandling = NullValueHandling.Ignore
}
)
看到的: 对象初始化器:命名和匿名类型(Visual Basic)
https://msdn.microsoft.com/en-us/library/bb385125.aspx
