api.versioning 版本控制自動識別最高版本-有解無憂

Microsoft.AspNetCore.Mvc.Versioning //引入程式集

.net core 下面api的版本控制作用不需要多說，可以查閱https://www.cnblogs.com/dc20181010/p/11313738.html

普通的版本控制一般是通過鏈接、header此類方法進行控制，對ApiVersionReader進行設定，例如

services.AddApiVersioning(o => {
                //o.ReportApiVersions = true;//回傳版本可使用的版本
                o.ApiVersionReader = ApiVersionReader.Combine(new HeaderApiVersionReader("api-version"), new QueryStringApiVersionReader("api-version"));//通過Header或QueryString進行傳值來判斷api的版本
                //o.DefaultApiVersion = new ApiVersion(1, 0);//默認版本號 
       });

或者使用https://www.cnblogs.com/tdfblog/p/asp-net-core-api-versioning.html這種方式

這兩種方式都需要傳遞api的版本資訊，如果不傳遞將會報錯

{"error":{"code":"ApiVersionUnspecified","message":"An API version is required, but was not specified.","innerError":null}}

如果我們不想傳遞api的版本資訊時，可以將

o.AssumeDefaultVersionWhenUnspecified = true; //此選項將用于在沒有版本的情況下提供請求
o.DefaultApiVersion = new ApiVersion(1, 0); //設定默認Api版本是1.0

打開，這個我們每次請求如果不傳遞版本資訊也不會報錯了，但我們的請求將會指向1.0版本，那么我想讓默認版本指向我寫的api里面的最高版本怎么做？

我們將默認版本修改為最高版本可以嗎？

這里將會出現一個問題，我的api版本可能由于各種各樣原因造成最高版本不一致的問題

所以我們不能采用指定默認版本是最高版本的方法來解決，這個最高版本還必須要是動態的，通過翻閱https://github.com/microsoft/aspnet-api-versioning/wiki/API-Version-Selector#current-implementation-api-selector可以得知

The CurrentImplementationApiVersionSelector selects the maximum API version available which does not have a version status. 
If no match is found, it falls back to the configured DefaultApiVersion. For example, if the versions "1.0", "2.0", and "3.0-Alpha" are available, 
then "2.0" will be selected because it's the highest, implemented or released API version.

CurrentImplementationApiVersionSelector選擇不具有版本狀態的最大可用API版本， 如果找不到匹配項，它將回退到配置的DefaultApiVersion，
 例如，如果提供版本“ 1.0”，“ 2.0”和“ 3.0-Alpha”，則將選擇“ 2.0”，因為它是最高，已實施或已發布的API版本，

services.AddApiVersioning(
    options => options.ApiVersionSelector =
        new CurrentImplementationApiVersionSelector( options ) );

通過這個版本選擇器，我們可以將最大版本得出，修改上面services.AddApiVersioning

services.AddApiVersioning(o => {
                o.ReportApiVersions = true;//回傳版本可使用的版本
                //o.ApiVersionReader = new UrlSegmentApiVersionReader();
                //o.ApiVersionReader = ApiVersionReader.Combine(new HeaderApiVersionReader("api-version"), new QueryStringApiVersionReader("api-version"));
                //o.ApiVersionReader = ApiVersionReader.Combine(new QueryStringApiVersionReader("api-version"));
                o.ApiVersionReader = ApiVersionReader.Combine(new HeaderApiVersionReader("api-version"));//版本號以什么形式，什么欄位傳遞
                o.AssumeDefaultVersionWhenUnspecified = true;//此選項將用于在沒有版本的情況下提供請求
                o.DefaultApiVersion = new ApiVersion(1, 0);//默認版本號
                o.ApiVersionSelector = new CurrentImplementationApiVersionSelector(o);//默認以當前最高版本進行訪問
            });

舉個栗子

namespace Default.v1.Controllers
{
    [ApiVersion("1.0")]
    [Route("[controller]/[action]")]
    [ApiController]
    public class HomeController : Controller, IBaseController
    {
        private readonly ILogger<HomeController> _logger;

        public HomeController (ILogger<HomeController> logger)
        {
            _logger = logger;
        }

        public JsonResult GetJson()
        {
            return Json("Home 1.0");
        }
}

Default.v1.Controllers.Home

namespace Default.v2.Controllers
{
    [ApiVersion("2.0")]
    [Route("[controller]/[action]")]
    [ApiController]
    public class HomeController : Controller, IBaseController
    {
        private readonly ILogger<HomeController> _logger;

        public HomeController (ILogger<HomeController> logger)
        {
            _logger = logger;
        }

        public JsonResult GetJson()
        {
            return Json("Home 2.0");
        }
}

Default.v2.Controllers.Home

namespace Default.v1.Controllers
{
    [ApiVersion("1.0")]
    [Route("[controller]/[action]")]
    [ApiController]
    public class TestController : Controller, IBaseController
    {
        private readonly ILogger<HomeController> _logger;

        public TestController (ILogger<HomeController> logger)
        {
            _logger = logger;
        }

        public JsonResult GetJson()
        {
            return Json("Test 1.0");
        }
}

Default.v1.Controllers.Test

我們在

請求/home/getjson 時回傳“Home 2.0”

請求/test/getjson 時回傳“Test 1.0”

這樣就可以動態的請求最高版本了

但是還是會有問題的，比如，在我添加了Area和User區域下的HomeController，且User區域下的HomeController增加了1.0和3.0版本之后，神奇的一幕出現了

我的HomeController進不去了，，，

{"error":{"code":"UnsupportedApiVersion","message":"The HTTP resource that matches the request URI 'https://localhost:44311/home/getjson' is not supported.","innerError":null}}

這個時候去google都查不到原因，，，

查看api-supported-versions，回傳的是1.0,2.0,3.0，，，我的api版本控制被污染了3.0版本從哪里來的哪？第一反應是從User區域來的

我現在在User區域下添加一個除了Home和Test以外Name的Controller就可以請求成功，這個讓我懷疑到是不是api.versioning本身的問題，首先懷疑的是Controller的Name問題，原始碼拉取下來，從添加版本控制的地方(services.AddApiVersioning)開始找

最后終于在ApiVersionCollator中找到了蛛絲馬跡

///https://github.com/microsoft/aspnet-api-versioning/blob/master/src/Microsoft.AspNetCore.Mvc.Versioning/Versioning/ApiVersionCollator.cs

namespace Microsoft.AspNetCore.Mvc.Versioning
{
    using Microsoft.AspNetCore.Mvc.Abstractions;
    using Microsoft.AspNetCore.Mvc.Controllers;
    using Microsoft.Extensions.Options;
    using System;
    using System.Collections.Generic;
    using System.Linq;

    /// <summary>
    /// Represents an object that collates <see cref="ApiVersion">API versions</see> per <see cref="ActionDescriptor">action</see>.
    /// </summary>
    [CLSCompliant( false )]
    public class ApiVersionCollator : IActionDescriptorProvider
    {
        readonly IOptions<ApiVersioningOptions> options;

        /// <summary>
        /// Initializes a new instance of the <see cref="ApiVersionCollator"/> class.
        /// </summary>
        /// <param name="options">The current <see cref="ApiVersioningOptions">API versioning options</see>.</param>
        public ApiVersionCollator( IOptions<ApiVersioningOptions> options ) => this.options = options;

        /// <summary>
        /// Gets the API versioning options associated with the collator.
        /// </summary>
        /// <value>The current <see cref="ApiVersioningOptions">API versioning options</see>.</value>
        protected ApiVersioningOptions Options => options.Value;

        /// <inheritdoc />
        public int Order { get; protected set; }

        /// <inheritdoc />
        public virtual void OnProvidersExecuted( ActionDescriptorProviderContext context )
        {
            if ( context == null )
            {
                throw new ArgumentNullException( nameof( context ) );
            }

            foreach ( var actions in GroupActionsByController( context.Results ) )
            {
                var collatedModel = CollateModel( actions );

                foreach ( var action in actions )
                {
                    var model = action.GetProperty<ApiVersionModel>();

                    if ( model != null && !model.IsApiVersionNeutral )
                    {
                        action.SetProperty( model.Aggregate( collatedModel ) );
                    }
                }
            }
        }

        /// <inheritdoc />
        public virtual void OnProvidersExecuting( ActionDescriptorProviderContext context ) { }

        /// <summary>
        /// Resolves and returns the logical controller name for the specified action.
        /// </summary>
        /// <param name="action">The <see cref="ActionDescriptor">action</see> to get the controller name from.</param>
        /// <returns>The logical name of the associated controller.</returns>
        /// <remarks>
        /// <para>
        /// The logical controller name is used to collate actions together and aggregate API versions. The
        /// default implementation uses the "controller" route parameter and falls back to the
        /// <see cref="ControllerActionDescriptor.ControllerName"/> property when available.
        /// </para>
        /// <para>
        /// The default implementation will also trim trailing numbers in the controller name by convention. For example,
        /// the type "Values2Controller" will have the controller name "Values2", which will be trimmed to just "Values".
        /// This behavior can be changed by using the <see cref="ControllerNameAttribute"/> or overriding the default
        /// implementation.
        /// </para>
        /// </remarks>
        protected virtual string GetControllerName( ActionDescriptor action )
        {
            if ( action == null )
            {
                throw new ArgumentNullException( nameof( action ) );
            }

            if ( !action.RouteValues.TryGetValue( "controller", out var key ) )
            {
                if ( action is ControllerActionDescriptor controllerAction )
                {
                    key = controllerAction.ControllerName;
                }
            }

            return TrimTrailingNumbers( key );
        }

        IEnumerable<IEnumerable<ActionDescriptor>> GroupActionsByController( IEnumerable<ActionDescriptor> actions )
        {
            var groups = new Dictionary<string, List<ActionDescriptor>>( StringComparer.OrdinalIgnoreCase );

            foreach ( var action in actions )
            {
                var key = GetControllerName( action );

                if ( string.IsNullOrEmpty( key ) )
                {
                    continue;
                }

                if ( !groups.TryGetValue( key, out var values ) )
                {
                    groups.Add( key, values = new List<ActionDescriptor>() );
                }

                values.Add( action );
            }

            foreach ( var value in groups.Values )
            {
                yield return value;
            }
        }

        static string TrimTrailingNumbers( string? name )
        {
            if ( string.IsNullOrEmpty( name ) )
            {
                return string.Empty;
            }

            var last = name!.Length - 1;

            for ( var i = last; i >= 0; i-- )
            {
                if ( !char.IsNumber( name[i] ) )
                {
                    if ( i < last )
                    {
                        return name.Substring( 0, i + 1 );
                    }

                    return name;
                }
            }

            return name;
        }

        static ApiVersionModel CollateModel( IEnumerable<ActionDescriptor> actions ) => actions.Select( a => a.GetApiVersionModel() ).Aggregate();
    }
}

View Code

其中GroupActionsByController將Controller按照Controller的名字進行分組，再看看內部，分組的時候將GetControllerName( action )作為key，那么GetControllerName是干嘛的，

protected virtual string GetControllerName( ActionDescriptor action )
        {
            if ( action == null )
            {
                throw new ArgumentNullException( nameof( action ) );
            }

            if ( !action.RouteValues.TryGetValue( "controller", out var key ) )
            {
                if ( action is ControllerActionDescriptor controllerAction )
                {
                    key = controllerAction.ControllerName;
                }
            }

            return TrimTrailingNumbers( key );
        }

這個方法原本是沒有問題的，但是牽扯到Area的時候就會出問題了，，它將根目錄下的HomeController和User.HomeController視為同一類的Controller然后去做版本的屬性注入，造成CurrentImplementationApiVersionSelector選擇器選不到正確的版本，所以回傳了上面的錯誤，我們將GetControllerName內部修改為

protected virtual string GetControllerName( ActionDescriptor action )
        {
            if ( action == null )
            {
                throw new ArgumentNullException( nameof( action ) );
            }

            if ( !action.RouteValues.TryGetValue( "controller", out var key ) )
            {
                if ( action is ControllerActionDescriptor controllerAction )
                {
                    key = controllerAction.ControllerName;
                }
            }

            if ( !action.RouteValues.TryGetValue( "area", out var area ) )
            {
            }

            return TrimTrailingNumbers( area + key );
        }

這樣就可以走通了

我們有兩種解決辦法，一個是把原始碼拉取下來，方法修改掉，專案的依賴項替換為自己修改的Microsoft.AspNetCore.Mvc.Versioning，另一種辦法是將services.AddApiVersioning重寫，，，請相信我，拉取修改替換依賴比重寫services.AddApiVersioning快且簡便，，，

issue：https://github.com/microsoft/aspnet-api-versioning/issues/630

轉載請註明出處，本文鏈接：https://www.uj5u.com/net/17082.html

標籤：.NET Core

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api.versioning 版本控制 自動識別最高版本

api.versioning 版本控制自動識別最高版本