如何将 IStringLocalizer 注入 IApplicationModelConvention？答案

【问题标题】：How to inject an IStringLocalizer into IApplicationModelConvention?如何将 IStringLocalizer 注入 IApplicationModelConvention？
【发布时间】：2019-05-21 01:12:07
【问题描述】：

我有一个自定义约定，需要在其中包含本地化字符串。 AFAIK 实例化 IStringLocalizer 的唯一方法是 DependencyInjection。

如何在我的 CustomConvention 中使用 IStringLocalizer？

约定是这样注册的

public void ConfigureServices(IServiceCollection services)
{
     //First I register the localization settings
     services.AddLocalization(o =>
     {
        o.ResourcesPath = "Resources";
     });

      services.AddMvc(options =>
      {
           //My custom convention, I would need to inject an IStringLocalizer  
           //into constructor here, but I can' instantiate it
           options.Conventions.Add(new LocalizationRouteConvention());
      })
}

【问题讨论】：

标签： asp.net-mvc asp.net-core .net-core

【解决方案1】：

我的解决方案并不漂亮。

您可以这样做，构建服务提供者以获取 StringLocalizer 的实例。

public void ConfigureServices(IServiceCollection services)
{
     //First I register the localization settings
     services.AddLocalization(o =>
     {
        o.ResourcesPath = "Resources";
     });

     var stringLocalizer = services.BuildServiceProvider().GetService<IStringLocalizer<Resource>>();

     services.AddMvc(options =>
     {
          //My custom convention, I would need to inject an IStringLocalizer  
          //into constructor here, but I can' instantiate it
          options.Conventions.Add(new LocalizationRouteConvention(stringLocalizer));
     })
}

【讨论】：

【解决方案2】：

我会建议这里提供的方法https://stackoverflow.com/a/61958762/4627333。

您基本上只需要注册您的类型并创建一个 IConfigureOptions<MvcOptions> 的实现，期待您的约定实现。 DI 将完成剩下的工作。

public class LocalizationRouteConventionMvcOptions : IConfigureOptions<MvcOptions>
{
    private readonly LocalizationRouteConvention _convention;

    public MyMvcOptions(LocalizationRouteConvention convention)
        => _convention = convention;

    public void Configure(MvcOptions options)
        => options.Conventions.Add(_convention);
}

public void ConfigureServices(IServiceCollection services)
{
    // or scoped, or transient, as necessary for your service
    services.AddTransient<IStringLocalizer<Resource>, MyStringLocalizer>();
    services.AddSingleton<LocalizationRouteConvention>();
    services.AddSingleton<IConfigureOptions<MvcOptions>, LocalizationRouteConventionMvcOptions>();

    services.AddControllers();
}

您的LocalizationRouteConvention 代码：

public sealed class LocalizationRouteConvention : IApplicationModelConvention
{
    private readonly IStringLocalizer<Resource> _stringLocalizer;

    public LocalizationRouteConvention(IStringLocalizer<Resource> stringLocalizer)
    {
        _stringLocalizer = stringLocalizer ?? throw new ArgumentNullException(nameof(stringLocalizer));
    }

    public void Apply(ApplicationModel application)
    {
        // ...
    }
}

【讨论】：