问题

我试图在最小API中返回一个元组，问题归结如下：

    app.MapPost("/colorkeyrect", () => server.ColorkeyRect());
    
    public (int x, int y, int w, int h) ColorkeyRect()
    {
      return (10, 10, 10, 10);
    }

但通过网络发送的数据是一个空的 JSON：

    content = await response.Content.ReadAsStringAsync();

> '{}'

    var obj = JsonConvert.DeserializeObject<(int, int, int, int)>(content);

因此，结果变成了(0, 0, 0, 0)，而不是(10, 10, 10, 10)。

在最小API应用中返回一个元组是否可能？
当仅依赖基本类型时，该怎么做才能获得一个有效的返回对象？

app.MapPost("/colorkeyrect", () => server.ColorkeyRect());

public (int x, int y, int w, int h) ColorkeyRect()
{
  return (10, 10, 10, 10);
}

content = await response.Content.ReadAsStringAsync();

var obj = JsonConvert.DeserializeObject<(int, int, int, int)>(content);

答案1

得分: 2

是的，这是可能的。默认情况下，System.Text.Json 不会序列化字段，而值元组的元素是字段（[`ValueTuple`][1]），所以你需要配置 `JsonOptions`（确保使用“正确”的选项 - 对于来自 `Microsoft.AspNetCore.Http.Json` 命名空间的 Minimal APIs）：

```csharp
builder.Services.Configure<JsonOptions>(options => options.SerializerOptions.IncludeFields = true);

但我认为这有点没用，值元组的名称是一些在运行时不表示的信息，所以你会得到这样的响应：

{"item1":1,"item2":2}

我建议要么使用匿名类型，要么只是创建一个 record（如果确实需要，则是 record struct），现在很容易创建新的 DTO 类型。而且使用目标类型化的新表达式也不会在方法中带来太大变化：

record Responce(int X, int Y, int W, int H); // 或者 record struct Responce ...

public Responce ColorkeyRect()
{
    return new (10, 10, 10, 10);
}

<details>
<summary>英文:</summary>

Yes, it is possible. By default System.Text.Json does not serialize fields, and value tuple elements are fields ([`ValueTuple`][1]), so you need to configure `JsonOptions` (be sure to use &quot;correct&quot; ones - for Minimal APIs from `Microsoft.AspNetCore.Http.Json` namespace):

```csharp
builder.Services.Configure&lt;JsonOptions&gt;(options =&gt; options.SerializerOptions.IncludeFields = true);

But I would argue that it is a bit useless, value tuple names is a piece of information which is not represented at runtime so you will get response like:

{"item1":1,"item2":2}

I would recommend to use either anonymous type or just create a record (record struct if really needed), it is very easy to create a new DTO type nowadays. And with target-typed new expressions it is not a big change in the method also:

record Responce(int X, int Y, int W, int H); // or record struct Responce ...

public Responce ColorkeyRect()
{
	return new (10, 10, 10, 10);
}