每个请求的 ASP.NET Core API JSON 序列化程序设置

ASP.NET Core API JSON serializersettings per request(每个请求的 ASP.NET Core API JSON 序列化程序设置)

问题描述

基于请求中的某些值(标头或 url)，我想更改我的 DTO 对象的序列化.为什么?好吧，我已将 [JsonProperty("A")] 应用于我的 DTO，但取决于它是否要使用该属性的客户端(网站或移动应用程序).我开始了

Based on some value in the request (header or in the url) I want to change the serialization of my DTO objects. Why? Well I've applied the [JsonProperty("A")] to my DTO's but depending on the client (website or mobile app) it want to use that property or not. I started with

services
.AddMvc()
.AddJsonOptions(opt =>
{
#if DEBUG
    opt.SerializerSettings.ContractResolver = new NoJsonPropertyNameContractResolver();
#endif
}

所以在调试时，我得到了带有完整属性名的 JSON.我使用 JsonProperty 属性来缩短响应 JSON，它适用于反序列化回相同 DTO 的移动应用程序 (Xamarin).但是现在我有一个网站，它使用相同的 API 通过 jQuery 获取数据，但在那里我想处理 DTO 的完整属性名称，而不是 JsonProperty 属性中给出的名称.网站和WebApi在同一个服务器，响应大一点也没问题.

So while debugging I get JSON with full propertynames. I use the JsonProperty attribute to shorten the response JSON, which works fine with the mobile app (Xamarin) which deserialize back to the same DTO's. But now I have a website which uses the the same API to get data via jQuery, but in there I want to deal with the full property names of the DTO's, not the name given in the JsonProperty attribute. Website and WebApi are on the same server so it's no problem if the response is a little bigger.

我从一个中间件类开始对客户标头值做出反应，这很有效，但现在我不知道如何访问 JSON SerializerSettings.在网上搜索但找不到.

I started with a middleware class to react on a customer header value, which works, but now I don't know how to get to the JSON SerializerSettings. Searched the web but cannot find it.

在搜索时，我阅读了有关 InputFormatters 和 OutputFormatters 以及内容协商的信息，但我不知道该往哪个方向发展.

While searching I've read about InputFormatters and OutputFormatters, and also content negotiation, but I don't know which direction I must go.

我不想使用不同的设置两次部署相同的 API.
如果有帮助，我可以更改诸如 routesconfig 之类的内容.

I don't want to deploy the same API twice with different settings.
I'am able to change things like the routesconfig if that would help.

更新
不仅 JSON 响应必须以两种不同的方式进行序列化，反序列化也必须以两种不同的方式进行.

Update
Not only the JSON response had to be serialized in 2 different ways, also the deserializing had to be done in 2 different ways.

推荐答案

感谢您的意见和回答.我找到了输入和输出格式化程序的解决方案.感谢 http://rovani.net/Explicit-Model-Constructor/ 指出我在正确的方向.

Thanks for the comments and answers. I found a solution with Input and outputformatters. With thanks to http://rovani.net/Explicit-Model-Constructor/ to point me in the right direction.

我创建了自己的输入和输出格式化程序，它们继承自 JsonInputFormatter 以保持尽可能多的功能相同.
在构造函数中，我设置了支持的媒体类型(使用了一些看起来像现有 JSON 的媒体类型).
还必须重写 CreateJsonSerializer 以将 ContractResolver 设置为所需的(可以实现单例).
必须这样做，因为更改构造函数中的 serializerSettings 会更改所有输入/输出格式化程序的序列化程序设置，这意味着默认的 JSON 格式化程序也将使用新的合约解析器.
这样做也意味着您可以通过 AddMvc().AddJsonOption()

I've created my own input and outputformatters, which inherit from JsonInputFormatter to keep as much functionality the same.
In the constructor I set the supported mediatype (used some that looks like the existing one for JSON).
Also must override CreateJsonSerializer to set the ContractResolver to the desired one (could implement singleton).
Must do it this way, because changing the serializerSettings in the constructor would change the serializersettings for all input/outputformatters, meaning the default JSON formatters will also use the new contract resolver.
Also doing it this way means you can setup some default JSON options via AddMvc().AddJsonOption()

示例inputformatter，outputformatter使用相同的原理:

Example inputformatter, outputformatter uses the same principle:

static MediaTypeHeaderValue protoMediaType = MediaTypeHeaderValue.Parse("application/jsonfull");

public JsonFullInputFormatter(ILogger logger, JsonSerializerSettings serializerSettings, ArrayPool<char> charPool, ObjectPoolProvider objectPoolProvider) 
    : base(logger, serializerSettings, charPool, objectPoolProvider)
{
    this.SupportedMediaTypes.Clear();
    this.SupportedMediaTypes.Add(protoMediaType);
}

protected override JsonSerializer CreateJsonSerializer()
{
    var serializer = base.CreateJsonSerializer();            
    serializer.ContractResolver = new NoJsonPropertyNameContractResolver();

    return serializer;
}

根据上面提到的安装类 URL:

As per the mentioned URL above the setup class:

public class YourMvcOptionsSetup : IConfigureOptions<MvcOptions>
{
    private readonly ILoggerFactory _loggerFactory;
    private readonly JsonSerializerSettings _jsonSerializerSettings;
    private readonly ArrayPool<char> _charPool;
    private readonly ObjectPoolProvider _objectPoolProvider;

    public YourMvcOptionsSetup(ILoggerFactory loggerFactory, IOptions<MvcJsonOptions> jsonOptions, ArrayPool<char> charPool, ObjectPoolProvider objectPoolProvider)
    {
        //Validate parameters and set fields
    }

    public void Configure(MvcOptions options)
    {
        var jsonFullInputFormatter = new JsonFullInputFormatter(
            _loggerFactory.CreateLogger<JsonFullInputFormatter>(),
            _jsonSerializerSettings,
            _charPool,
            _objectPoolProvider
        );

        options.InputFormatters.Add(jsonFullInputFormatter);

        options.OutputFormatters.Add(new JsonFullOutputFormatter(
            _jsonSerializerSettings,
            _charPool
        ));
    }

然后是一个扩展方法来注册它:

And then an extension method to register it:

public static class MvcBuilderExtensions
{
    public static IMvcBuilder AddJsonFullFormatters(this IMvcBuilder builder)
    {
        if (builder == null)
        {
            throw new ArgumentNullException(nameof(builder));
        }
        ServiceDescriptor descriptor = ServiceDescriptor.Transient<IConfigureOptions<MvcOptions>, YourMvcOptionsSetup>();
        builder.Services.TryAddEnumerable(descriptor);
        return builder;
    }
}

在ConfigureServices中调用它:

services.AddMvc(config =>
{
    config.RespectBrowserAcceptHeader = true; // To use the JsonFullFormatters if clients asks about it via Accept Header
})
.AddJsonFullFormatters() //Add our own JSON Formatters
.AddJsonOptions(opt =>
{
     //Set up some default options all JSON formatters must use (if any)
});

现在我们的 Xamarin 应用可以访问 webapi 并接收带有通过 JsonProperty 属性设置的(短)属性名称的 JSON.
在网站中，我们可以通过添加 Accept(get 调用)和 ContentType(post/put 调用)标头来获取完整的 JSON 属性名称.我们通过 jQuery 的 $.ajaxSetup(.

Now our Xamarin App can access the webapi and receive JSON with (short) property names set via JsonProperty attribute.
And in the website we can get the full JSON property names by adding an Accept (get calls) and ContentType (post/put calls) header. Which we do once via jQuery's $.ajaxSetup(.

$.ajaxSetup({
    contentType: "application/jsonfull; charset=utf-8",
    headers: { 'Accept': 'application/jsonfull' }
});

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