c# - 是否可以在 Controller 的 ApiVersion 属性中包含下划线？

Question

我继承了一个遗留的 WebAPI 系统，该系统目前在路由模式中使用下划线来表示版本。例如/api/1_0/account, /api/1_1/account等

我正在尝试更新自动生成的文档以使用 Swagger，但是使用包含下划线的 ApiVersion 属性的显式路由会导致异常。例如，这很好用:

[ApiVersion("1")]

但是这会引发异常:

[ApiVersion("1_0")] // < note '_0' here
[RoutePrefix("api/{version:apiVersion}/account")]
public class AccountController : ApiBaseController
{
  // actions...
}

异常(exception)情况是:

FormatException: The specified API version status '_1' is invalid.
System.InvalidOperationException: 'Failed to compare two elements in the array.'
at System.Collections.Generic.ArraySortHelper`1.Sort(T[] keys, Int32 index, Int32 length, IComparer`1 comparer)
at System.Array.Sort[T](T[] array, Int32 index, Int32 length, IComparer`1 comparer)
at System.Collections.Generic.List`1.Sort(Int32 index, Int32 count, IComparer`1 comparer)
at Microsoft.Web.Http.Dispatcher.ApiVersionControllerSelector.InitializeControllerInfoCache()
at System.Lazy`1.CreateValue()
at System.Lazy`1.LazyInitValue()
at System.Lazy`1.get_Value()
at Microsoft.Web.Http.Dispatcher.ApiVersionControllerSelector.GetControllerMapping()
at System.Web.Http.Routing.AttributeRoutingMapper.AddRouteEntries(SubRouteCollection collector, HttpConfiguration configuration, IInlineConstraintResolver constraintResolver, IDirectRouteProvider directRouteProvider)
at System.Web.Http.Routing.AttributeRoutingMapper.<>c__DisplayClass1_1.b__1()
at System.Web.Http.Routing.RouteCollectionRoute.EnsureInitialized(Func`1 initializer)
at System.Web.Http.Routing.AttributeRoutingMapper.<>c__DisplayClass1_0.b__0(HttpConfiguration config)
at System.Web.Http.HttpConfiguration.EnsureInitialized()
at ProjectName.Startup.Configuration(IAppBuilder app) in E:\ProjectPath\Foo.cs:line 25

问题很明显，但是如何在版本属性值中包含下划线呢？这个问题令人困惑，因为我假设类的内部(在某些时候)将值解析为整数，但属性本身接受一个字符串......？那为什么会这样呢？

Answer 1

关于为什么这不起作用的一些附加信息。 Microsoft.AspNet.WebApi.Versioning包裹如下 semantic versioning要求主要部分和次要部分之间的分隔符是句号的规则。查看rules对于这个包。

通过一些技巧，可以获取 API 版本控制包来解析下划线。这是非常基本的代码，可能还没有准备好生产，但应该给你一个方向。您需要的第一件事是自定义路由约束(本质上是扯掉 the default one ):

public class CustomApiVersionRouteConstraint : IHttpRouteConstraint
{
    public bool Match(HttpRequestMessage request, IHttpRoute route, string parameterName, 
        IDictionary<string, object> values, HttpRouteDirection routeDirection)
    {
        if (string.IsNullOrEmpty(parameterName))
        {
            return false;
        }

        var properties = request.ApiVersionProperties();
        var versionString = "";

        if (values.TryGetValue(parameterName, out object value))
        {
            //This is the real 'magic' here, just replacing the underscore with a period
            versionString = ((string) value).Replace('_', '.');

            properties.RawApiVersion = versionString;
        }
        else
        {
            return false;
        }


        if (ApiVersion.TryParse(versionString, out var requestedVersion))
        {
            properties.ApiVersion = requestedVersion;
            return true;
        }

        return false;
    }
}

并确保 Web API 使用新约束:

var constraintResolver = new DefaultInlineConstraintResolver()
{
    ConstraintMap =
    {
        ["apiVersion"] = typeof( CustomApiVersionRouteConstraint )
    }
};

config.MapHttpAttributeRoutes(constraintResolver);