每个请求的ASP.NET Core API JSON序列化程序设置 [英] ASP.NET Core API JSON serializersettings per request

问题描述

基于请求(标头或url)中的某些值，我想更改DTO对象的序列化. 为什么?好吧，我已经将[JsonProperty("A")]应用于我的DTO，但是根据客户端(网站或移动应用程序)的不同，它是否要使用该属性. 我从

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
}

因此，在调试时，我会获得具有完整属性名的JSON.我使用JsonProperty属性来缩短响应JSON，这与在反序列化为相同DTO的移动应用程序(Xamarin)上正常工作. 但是现在我有了一个使用相同API通过jQuery获取数据的网站，但是在这里我想处理DTO的完整属性名称，而不是JsonProperty属性中给出的名称. 网站和WebApi位于同一台服务器上，因此响应稍大一点也没问题.

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.

我从中间件类开始，以对客户标头值做出反应，该方法有效，但是现在我不知道如何获取JSON SerializerSettings.搜索了网络，但找不到它.

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，我已经阅读了有关InputFormatters和OutputFormatters以及内容协商的信息，但是我不知道必须走哪个方向.

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.
如果有帮助的话，我可以更改routesconfig之类的东西.

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
不仅必须以2种不同的方式序列化JSON响应，而且还必须以2种不同的方式进行反序列化.

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

感谢您的评论和回答.我找到了使用Input和OutputFormatters的解决方案.感谢 http://rovani.net/Explicit-Model-Constructor/指出我朝着正确的方向前进.

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器，它们继承自JsonInputFormatter以保持相同的功能.
在构造函数中，我设置了受支持的媒体类型(使用了一些类似JSON的媒体类型).
还必须重写CreateJsonSerializer，以将ContractResolver设置为所需的值(可以实现单例).
必须这样做，因为在构造函数中更改serializerSettings会更改所有输入/输出格式器的序列化器设置，这意味着默认的JSON格式器也将使用新的协定解析器. 同样，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()

inputformatter示例，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;
}

按照设置类上方的上述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
        ));
    }

然后是注册它的扩展方法:

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应用程序可以访问webapi并接收具有通过JsonProperty属性设置的(简短)属性名称的JSON.
在网站上，我们可以通过添加Accept(获取调用)和ContentType(发布/放置调用)标头来获得完整的JSON属性名称.我们通过jQuery的$.ajaxSetup(做了一次.

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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