在aspnet方法的JSON输出中全局忽略null值

Question

新手问题：如何使JSON输出忽略null值？我不想把每个单独的属性都设置为忽略null(就像用[JsonProperty(NullValueHandling = NullValueHandling.Ignore)]装饰每个属性一样(，我发现并尝试过的几种不同的全局方法都不起作用。我正在使用.Net 6和Newtonsoft.Json

我在我的控制器中有这个方法

[HttpPost]
public async Task<ResponseJson> Post([FromBody] RequestJson value)
{
DataProcessor processor = new DataProcessor(value);
return processor.GetResults();
}

这就是ResponseJson的样子(为了简洁起见，省略了一些属性(。

public class ResponseJson
{
[JsonProperty(PropertyName = "items")]
public List<Item> Items { get; set; }
}   
public class Item
{
[JsonProperty(PropertyName = "name")]
public string name { get; set; }

[JsonProperty(PropertyName = "colour")]
public string colour { get; set; }

[JsonProperty(PropertyName = "parameters")]
public ItemParameters parameters { get; set; }
}

DataProcessor不设置colour(null(，或者对于一些Item根本不设置ItemParameters。当查看调用此方法的响应时，JSON字符串如下所示：

{
"items":
[
{
"name":"abc",
"colour": "blue",
"parameters":{<a bunch of parameters>}
},
{
"name":"def",
"colour": null
"parameters":null
},
{
"name":"ghi",
"colour": null,
"parameters":null
},
{
"name":"jkl",
"colour": "red",
"parameters":{<a bunch of parameters>}
}
]
}   

我希望完全忽略具有null值的属性，使其看起来像这样：

{
"items":
[
{
"name":"abc",
"colour": "blue",
"parameters":{<a bunch of parameters>}
},
{
"name":"def"
},
{
"name":"ghi"
},
{
"name":"jkl",
"colour": "red",
"parameters":{<a bunch of parameters>}
}
]
}   

Answer 1

net core 6 web api，在程序中，在AddControllers中添加AddJsonOptions

var builder = WebApplication.CreateBuilder(args);
builder.Services.AddControllers().AddJsonOptions(options =>
{ 
options.JsonSerializerOptions.DefaultIgnoreCondition = JsonIgnoreCondition.WhenWritingNull;
});

网芯mvc

services.AddControllersWithViews().AddJsonOptions(options =>
{
options.JsonSerializerOptions.DefaultIgnoreCondition = JsonIgnoreCondition.WhenWritingNull;
});

在最小API中创建服务

builder.Services.Configure<JsonOptions>(options =>
{
// Set this to true to ignore null or default values
options.SerializerOptions.DefaultIgnoreCondition = System.Text.Json.Serialization.JsonIgnoreCondition.WhenWritingNull;
});

使用最小API 完成示例

using Microsoft.AspNetCore.Http.Json;
var builder = WebApplication.CreateBuilder(args);
// Add services to the container.
// Learn more about configuring Swagger/OpenAPI at https://aka.ms/aspnetcore/swashbuckle
builder.Services.AddEndpointsApiExplorer();
builder.Services.AddSwaggerGen();
builder.Services.Configure<JsonOptions>(options =>
{
// Set this to true to ignore null or default values
options.SerializerOptions.DefaultIgnoreCondition = System.Text.Json.Serialization.JsonIgnoreCondition.WhenWritingNull;
});
var app = builder.Build();
// Configure the HTTP request pipeline.
if (app.Environment.IsDevelopment())
{
app.UseSwagger();
app.UseSwaggerUI();
}

app.MapGet("/GetWeatherForecast", () => new Person { FirstName = "Gérald"});
app.Run();
public class Person
{
public string? FirstName { get; set; }
public string? LastName { get; set; }
}

无忽略空的结果

{
"FirstName": "Gérald",
"LastName": null
}

结果忽略空

{
"firstName": "Gérald"
}

Answer 2

你尝试过这种方式吗？

services.AddControllersWithViews().AddNewtonsoftJson(o => {   o.SerializerSettings.NullValueHandling = Newtonsoft.Json.NullValueHandling.Ignore;   });

Answer 3

在Startup.cs文件中的ConfigureServices方法中添加以下代码，它将工作

services.AddMvc()
.AddJsonOptions(options =>
{
options.JsonSerializerOptions.IgnoreNullValues = true;
});

JsonSerializerOptions.IgnoreNullValues字段现在似乎已经过时了，所以请尝试如下所述的新方法：

services.AddMvc()
.AddJsonOptions(options =>
{
options.JsonSerializerOptions.DefaultIgnoreCondition = JsonIgnoreCondition.WhenWritingNull;
});

Answer 4

对于在DOTNET 7+中运行的Minimal API(可能也是6(，现在它就像Minimal API教程的配置JSON序列化选项部分所显示的那样简单。只需按照以下摘录使用Builder.Services.ConfigureHttpJsonOptions()：

var builder = WebApplication.CreateBuilder(args);
builder.Services.ConfigureHttpJsonOptions(options => {
options.SerializerOptions.DefaultIgnoreCondition = JsonIgnoreCondition.WhenWritingNull;
// set other desired options here...
options.SerializerOptions.WriteIndented = true;
options.SerializerOptions.IncludeFields = true;
});
var app = builder.Build();