在 aspnet 方法中全局忽略 JSON 输出中的空值

Question

新手问题：如何使 JSON 输出忽略null值？我不想一定将每个单独的属性设置为忽略null（如用 装饰每个属性[JsonProperty(NullValueHandling = NullValueHandling.Ignore)]），并且我发现并尝试的几种不同的全局方法不起作用。我正在使用 .Net 6 和 Newtonsoft.Json

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看起来的样子（为简洁起见，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)，或者根本不设置ItemParameters某些Item. 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>}
            }
        ]
}   

null我希望完全忽略具有值的属性，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，AddJsonOptions添加AddControllers

\n

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

\n

在.net core mvc中

\n

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

\n

用最少的 API 创建服务

\n

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

\n

使用最少的 API 完成示例

\n

using Microsoft.AspNetCore.Http.Json;\n\nvar builder = WebApplication.CreateBuilder(args);\n\n// Add services to the container.\n// Learn more about configuring Swagger/OpenAPI at https://aka.ms/aspnetcore/swashbuckle\nbuilder.Services.AddEndpointsApiExplorer();\nbuilder.Services.AddSwaggerGen();\n\nbuilder.Services.Configure<JsonOptions>(options =>\n{\n    // Set this to true to ignore null or default values\n    options.SerializerOptions.DefaultIgnoreCondition = System.Text.Json.Serialization.JsonIgnoreCondition.WhenWritingNull;\n});\n\nvar app = builder.Build();\n\n// Configure the HTTP request pipeline.\nif (app.Environment.IsDevelopment())\n{\n    app.UseSwagger();\n    app.UseSwaggerUI();\n}\n\n\napp.MapGet("/GetWeatherForecast", () => new Person { FirstName = "G\xc3\xa9rald"});\napp.Run();\n\npublic class Person\n{\n    public string? FirstName { get; set; }\n    public string? LastName { get; set; }\n}\n

\n

结果不忽略 null

\n

{\n  "FirstName": "G\xc3\xa9rald",\n  "LastName": null\n}\n

\n

结果忽略空值

\n

{\n  "firstName": "G\xc3\xa9rald"\n}\n

\n