Asp.net core 多语言下拉列表还原为默认选择

好的，我现在有了语言，它正在为下拉列表中选择的语言选择合适的语言。但是，下拉列表不会记住正在写入cookie的所选语言，但会返回默认值。 我发现微软官方文档在这个细节上非常缺乏，我使用的是管理lte主题

SelectLanguage.Html

@using Microsoft.AspNetCore.Builder
@using Microsoft.AspNetCore.Mvc.Localization
@using Microsoft.Extensions.Options

@inject IViewLocalizer Localizer
@inject IOptions<RequestLocalizationOptions> LocOptions

@{
    var cultureItems = LocOptions.Value.SupportedUICultures
        .Select(c => new SelectListItem { Value = c.Name, Text = c.NativeName })
        .ToList();
    var returnUrl = string.IsNullOrEmpty(Context.Request.Path) ? "~/" : $"~{Context.Request.Path.Value}";
}

<li class="nav-item dropdown">
    <a class="nav-link dropdown-toggle" href="#" id="languageDropdown" role="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
        @Localizer["Language"]
    </a>
    <div class="dropdown-menu" aria-labelledby="languageDropdown">
        @foreach (var language in @cultureItems)
        {
            <a class="dropdown-item" asp-controller="Home" asp-action="SetLanguage" asp-route-culture="@language.Value" asp-route-returnUrl="@returnUrl">@language.Text</a>
        }
    </div>
</li>

在我的家庭控制器中，我设置了以下内容

 public HomeController(ILogger<HomeController> logger, IStringLocalizer<HomeController> localizer)   
 {
     _logger = logger;
     _localizer = localizer;           

   }

公共家庭控制器（ILogger记录器、IStringLocalizer定位器）
{
_记录器=记录器；
_定位器=定位器；
}

这是我的创业课

namespace RoundTableMVCore31
{
    public class Startup
    {
        public Startup(IConfiguration configuration)
        {
            Configuration = configuration;
        }

        public IConfiguration Configuration { get; }

        // This method gets called by the runtime. Use this method to add services to the container.
        public void ConfigureServices(IServiceCollection services)
        {
            services.Configure<CookiePolicyOptions>(options =>
            {
                // This lambda determines whether user consent for non-essential cookies is needed for a given request.
                options.MinimumSameSitePolicy = SameSiteMode.None;
            });

            services.AddLocalization(options => { options.ResourcesPath = "Resources"; });
            services.Configure<RequestLocalizationOptions>(options =>
            {
                var supportedCultures = new[] { new CultureInfo("en"), new CultureInfo("fr") };

                options.DefaultRequestCulture = new RequestCulture(culture: "en", uiCulture: "en");
                options.SupportedCultures = supportedCultures;
                options.SupportedUICultures = supportedCultures;
                options.RequestCultureProviders = new List<IRequestCultureProvider>
                {
                    new QueryStringRequestCultureProvider(),
                    new CookieRequestCultureProvider()
                };
            });


            services.AddDbContext<ApplicationDbContext>(options =>
                options.UseSqlServer(
                    Configuration.GetConnectionString("DefaultConnection")));
            services.AddDefaultIdentity<IdentityUser>(options => options.SignIn.RequireConfirmedAccount = true)
                .AddEntityFrameworkStores<ApplicationDbContext>();
            services.AddControllersWithViews();
            services.AddRazorPages();
            services
                .AddMvc()
                .AddViewLocalization(LanguageViewLocationExpanderFormat.Suffix);


        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
        {
            var supportedCultures = new string[] { "en-GB", "fr-FR" };

            app.UseRequestLocalization();
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
                app.UseDatabaseErrorPage();
            }
            else
            {
                app.UseExceptionHandler("/Home/Error");
                // The default HSTS value is 30 days. You may want to change this for production scenarios, see https://aka.ms/aspnetcore-hsts.
                app.UseHsts();
            }
            app.UseHttpsRedirection();
            app.UseStaticFiles();
            app.UseCookiePolicy();

            app.UseRouting();

            app.UseAuthentication();
            app.UseAuthorization();

            app.UseEndpoints(endpoints =>
            {
                endpoints.MapControllerRoute(
                    name: "default",
                    pattern: "{culture=en-gb}/{controller=Home}/{action=Index}/{id?}");
                endpoints.MapRazorPages();


            });


        }
    }
}

名称空间圆桌会议MVCore31
{
公营创业
{
公共启动（IConfiguration配置）
{
配置=配置；
}
公共IConfiguration配置{get；}
//此方法由运行时调用。请使用此方法将服务添加到容器中。
public void配置服务（IServiceCollection服务）
{
配置（选项=>
{
//此lambda确定给定请求是否需要非必要cookie的用户同意。
options.MinimumSameSitePolicy=SameSiteMode.None；
});
AddLocalization（options=>{options.ResourcesPath=“Resources”；}）；
配置（选项=>
{
var supportedCultures=new[]{new CultureInfo（“en”）、new CultureInfo（“fr”）}；
options.DefaultRequestCulture=新的RequestCulture（区域性：“en”，uiCulture：“en”）；
options.SupportedCultures=SupportedCultures；
options.supportedCultures=supportedCultures；
options.RequestCultureProviders=新列表
{
新建QueryStringRequestCultureProvider（），
新CookiierRequestCultureProvider（）
};
});
services.AddDbContext（选项=>
options.UseSqlServer(
GetConnectionString（“DefaultConnection”）；
services.AddDefaultIdentity（options=>options.SignIn.RequireConfirmedAccount=true）
.AddEntityFrameworkStores（）；
services.AddControllersWithViews（）；
services.AddRazorPages（）；
服务
.AddMvc（）
.AddViewLocalization（LanguageViewLocationExpanderFormat.后缀）；
}
//此方法由运行时调用。请使用此方法配置HTTP请求管道。
public void配置（IApplicationBuilder应用程序、IWebHostEnvironment环境）
{
var-supportedCultures=新字符串[]{“en-GB”，“fr-fr”}；
app.UseRequestLocalization（）；
if（env.IsDevelopment（））
{
app.UseDeveloperExceptionPage（）；
app.UseDatabaseErrorPage（）；
}
其他的
{
app.UseExceptionHandler（“/Home/Error”）；
//默认的HSTS值为30天。您可能希望在生产场景中更改此值，请参阅https://aka.ms/aspnetcore-hsts.
app.UseHsts（）；
}
app.UseHttpsRedirection（）；
app.UseStaticFiles（）；
app.UseCookiePolicy（）；
app.UseRouting（）；
app.UseAuthentication（）；
app.UseAuthorization（）；
app.UseEndpoints（端点=>
{
endpoints.MapControllerRoute(
名称：“默认”，
模式：“{culture=en gb}/{controller=Home}/{action=Index}/{id？}”）；
endpoints.MapRazorPages（）；
});
}
}
}

此外，如何包括国旗有一个标准的方式这样做

下拉列表不会记住正在写入cookie的所选语言，但会返回默认值

如果要在更改选定语言后保持下拉列表中选定项的“活动””状态，可以根据cookie的值为选定项动态指定

.Active

CSS类，如下所示

在_Layout.cshtml文件中

$（函数（）{
var cl=getCookie（“.AspNetCore.Culture”）；
如果（cl！=“”）{
var c=cl.split（“|”）[0]。子字符串（2）；
//控制台日志（c）；
$（“#lan items a.active”）.removeClass（“active”）；
//你的代码逻辑在这里
开关（c）{
案例“fr”：
var atag=$（“#lan项目a.dropdown-item”）[1]；
$（atag）.addClass（“活动”）；
打破
案例“en”：
var atag=$（“#lan项目a.dropdown-item”）[0]；
$（atag）.addClass（“活动”）；
打破
}
}
})
函数getCookie（cname）{
变量名称=cname+“=”；
var decodedCookie=decodeURIComponent（document.cookie）；
var ca=decodedCookie.split（“；”）；
对于（变量i=0；i

指定id为“lan项”的下拉菜单div

@foreach（@cultureItems中的var语言）
{
谢谢，ms文档中没有这一步，我相信应该添加这一步。只是想知道如何添加lanugage标志，这是可能的吗
namespace RoundTableMVCore31
{
    public class Startup
    {
        public Startup(IConfiguration configuration)
        {
            Configuration = configuration;
        }

        public IConfiguration Configuration { get; }

        // This method gets called by the runtime. Use this method to add services to the container.
        public void ConfigureServices(IServiceCollection services)
        {
            services.Configure<CookiePolicyOptions>(options =>
            {
                // This lambda determines whether user consent for non-essential cookies is needed for a given request.
                options.MinimumSameSitePolicy = SameSiteMode.None;
            });

            services.AddLocalization(options => { options.ResourcesPath = "Resources"; });
            services.Configure<RequestLocalizationOptions>(options =>
            {
                var supportedCultures = new[] { new CultureInfo("en"), new CultureInfo("fr") };

                options.DefaultRequestCulture = new RequestCulture(culture: "en", uiCulture: "en");
                options.SupportedCultures = supportedCultures;
                options.SupportedUICultures = supportedCultures;
                options.RequestCultureProviders = new List<IRequestCultureProvider>
                {
                    new QueryStringRequestCultureProvider(),
                    new CookieRequestCultureProvider()
                };
            });


            services.AddDbContext<ApplicationDbContext>(options =>
                options.UseSqlServer(
                    Configuration.GetConnectionString("DefaultConnection")));
            services.AddDefaultIdentity<IdentityUser>(options => options.SignIn.RequireConfirmedAccount = true)
                .AddEntityFrameworkStores<ApplicationDbContext>();
            services.AddControllersWithViews();
            services.AddRazorPages();
            services
                .AddMvc()
                .AddViewLocalization(LanguageViewLocationExpanderFormat.Suffix);


        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
        {
            var supportedCultures = new string[] { "en-GB", "fr-FR" };

            app.UseRequestLocalization();
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
                app.UseDatabaseErrorPage();
            }
            else
            {
                app.UseExceptionHandler("/Home/Error");
                // The default HSTS value is 30 days. You may want to change this for production scenarios, see https://aka.ms/aspnetcore-hsts.
                app.UseHsts();
            }
            app.UseHttpsRedirection();
            app.UseStaticFiles();
            app.UseCookiePolicy();

            app.UseRouting();

            app.UseAuthentication();
            app.UseAuthorization();

            app.UseEndpoints(endpoints =>
            {
                endpoints.MapControllerRoute(
                    name: "default",
                    pattern: "{culture=en-gb}/{controller=Home}/{action=Index}/{id?}");
                endpoints.MapRazorPages();


            });


        }
    }
}

<script>
    $(function () {
        var cl = getCookie(".AspNetCore.Culture");
        if (cl != "") {
            var c = cl.split('|')[0].substring(2);
            //console.log(c);

            $("#lan-items a.active").removeClass("active");

            //your code logic here

            switch (c) {
                case "fr":
                    var atag = $("#lan-items a.dropdown-item")[1];

                    $(atag).addClass("active");
                    break;

                case "en":
                    var atag = $("#lan-items a.dropdown-item")[0];

                    $(atag).addClass("active");
                    break;
            }
        }
    })

    function getCookie(cname) {
        var name = cname + "=";
        var decodedCookie = decodeURIComponent(document.cookie);
        var ca = decodedCookie.split(';');
        for (var i = 0; i < ca.length; i++) {
            var c = ca[i];
            while (c.charAt(0) == ' ') {
                c = c.substring(1);
            }
            if (c.indexOf(name) == 0) {
                return c.substring(name.length, c.length);
            }
        }
        return "";
    }
</script>

<div class="dropdown-menu" id="lan-items" aria-labelledby="languageDropdown">
    @foreach (var language in @cultureItems)
    {
        <a class="dropdown-item" asp-controller="Home" asp-action="SetLanguage" asp-route-culture="@language.Value" asp-route-returnUrl="@returnUrl">@language.Text</a>
    }
</div>