我有一个看起来像这样的命令:

public interface ICommand {
    // Just a marker interface
}

public interface IUserAware {
    Guid UserId { get; set; }
}

public class CreateSomething : ICommand, IUserAware
{
    public string Title { get; set; }

    public Guid UserId { get; set; }
}

REST 请求是:

PUT /create HTTP/1.1
UserId: 7da6f9ee-2bfc-70b1-f93c-10c950c8f6b0 // Possible an Auth token and not a userId like here.
Host: localhost:63079
Content-Type: application/json
Cache-Control: no-cache
{
    "title": "This is a test title"
}

我有一个 API Controller 操作:

[HttpPut, Route("create")]
public IHttpActionResult CreateSomething([FromBody]CreateSomething command)
{
    // I would like command.UserId already binded here
}

我模型上的 Title 属性填充了请求的主体，但我想使用请求中的一些值来绑定(bind) command.UserId 属性 header (例如来自身份验证 token )。

我如何从请求 header 值绑定(bind) IUserAware 的属性，例如一个模型绑定(bind)器，无需为具体类 CreateSomething?

我已经在 Web API 中尝试了 IModelBinder 接口(interface)的各种组合，但没有真正的运气。

使用起来也感觉多余:

[HttpPut, Route("create")]
public IHttpActionResult CreateSomething([FromBody]CreateSomething command)
{
    command.UserId = GetUserIdFromTheRequest();
}

或者从 Controller 的依赖项中获取 UserId 并像上面那样设置它。

在 ASP.NET MVC 中是如何完成的

在 ASP.NET MVC 中，可以执行以下操作使其工作:

public class UserAwareModelBinder : DefaultModelBinder
{
    protected override object CreateModel(ControllerContext controllerContext, ModelBindingContext bindingContext, System.Type modelType)
    {
        var baseModel = base.CreateModel(controllerContext, bindingContext, modelType);
        var commandModel = baseModel as IUserAware;
        if (commandModel != null) 
        {
             commandModel.UserId = controllerContext.HttpContext.User; // or get it from the HttpContext headers.
        }

        return baseModel;
    }
}

并在启动时连接它:

ModelBinders.Binders.DefaultBinder = new UserAwareModelBinder();

最佳答案

根据@Todd 的最后评论，问题的答案是:

创建一个 HttpParameterBinding 类:

public class UserAwareHttpParameterBinding : HttpParameterBinding
{
    private readonly HttpParameterBinding _paramaterBinding;
    private readonly HttpParameterDescriptor _httpParameterDescriptor;

    public UserAwareHttpParameterBinding(HttpParameterDescriptor descriptor) : base(descriptor)
    {
        _httpParameterDescriptor = descriptor;
        _paramaterBinding = new FromBodyAttribute().GetBinding(descriptor);
    }

    public override async Task ExecuteBindingAsync(ModelMetadataProvider metadataProvider, HttpActionContext actionContext, CancellationToken cancellationToken)
    {
        await _paramaterBinding.ExecuteBindingAsync(metadataProvider, actionContext, cancellationToken);

        var baseModel = actionContext.ActionArguments[_httpParameterDescriptor.ParameterName] as IUserAware;
        if (baseModel != null)
        {
            baseModel.UserId = new Guid("6ed85eb7-e55b-4049-a5de-d977003e020f"); // Or get it form the actionContext.RequestContext!
        }
    }
}

并将其连接到 HttpConfiguration 中:

configuration.ParameterBindingRules.Insert(0, descriptor => typeof(IUserAware).IsAssignableFrom(descriptor.ParameterType) ? new UserAwareHttpParameterBinding(descriptor) : null);

If anyone know how this is done in .NET Core MVC - please edit this post or comment.

关于c# - 使用 Web API 的模型绑定(bind)接口(interface)属性，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/38953348/