问题描述

是否可以自定义在 ASP.NET Core MVC 中将类型序列化为响应的方式?

Is it possible to customize the way types are serialized to the response in ASP.NET Core MVC?

在我的特定用例中，我有一个结构 AccountId，它简单地包裹着一个 Guid:

In my particular use case I've got a struct, AccountId, that simply wraps around a Guid:

public readonly struct AccountId
{
    public Guid Value { get; }

    // ... 
}

当我从动作方法返回它时，不出所料，它会序列化为以下内容:

When I return it from an action method, unsurprisingly, it serializes to the following:

{ "value": "F6556C1D-1E8A-4D25-AB06-E8E244067D04" }

相反，我想自动解开 Value 以便它序列化为纯字符串:

Instead, I'd like to automatically unwrap the Value so it serializes to a plain string:

"F6556C1D-1E8A-4D25-AB06-E8E244067D04"

可以配置 MVC 来实现这一点吗?

Can MVC be configured to achieve this?

推荐答案

您可以使用 自定义转换器.

在你的情况下，它看起来像这样:

In your case, it would look like this:

[JsonConverter(typeof(AccountIdConverter))]
public readonly struct AccountId
{
    public Guid Value { get; }

    // ... 
}

public class AccountIdConverter : JsonConverter
{
    public override bool CanConvert(Type objectType)
        => objectType == typeof(AccountId);

    // this converter is only used for serialization, not to deserialize
    public override bool CanRead => false;

    // implement this if you need to read the string representation to create an AccountId
    public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
        => throw new NotImplementedException();

    public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
    {
        if (!(value is AccountId accountId))
            throw new JsonSerializationException("Expected AccountId object value.");

        // custom response 
        writer.WriteValue(accountId.Value);
    }
}

如果您不想使用 JsonConverter 属性，可以在 ConfigureServices 中添加转换器(需要 Microsoft.AspNetCore.Mvc.Formatters.Json):

public void ConfigureServices(IServiceCollection services)
{
    services
        .AddMvc()
        .AddJsonOptions(options => {
            options.SerializerSettings.Converters.Add(new AccountIdConverter());
        });
}