Creating Language Dropdown Navigation

• Developing Multicultural Web Application
  • Creating Startup Project
  • Configuring Culture Route Model
  • Localizing Request
  • Creating Language Dropdown Navigation
  • Localizing Views
  • Localizing DataAnnotations
  • Localizing ModelBinding Error Messages
  • Configuring Client Side Validation

We can simply create a dropdown list and fill culture items manually, but it is better to retrieve supported cultures list from RequestLocalization Options.

Under Pages/Shared folder create a new razor view and name it “_LanguagePartial.cshtml”, 

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

@inject IOptions<RequestLocalizationOptions> LocOps

@{
    var requestCulture = CultureInfo.CurrentCulture;

    var supportedCultures = LocOps.Value.SupportedUICultures

        .Select(c => new SelectListItem
        {
            Value = $"{c.Name}",
            Text = $"{c.DisplayName}"
        }).ToList();

    var routeData = new Dictionary<string, string>();

    foreach (var r in ViewContext.RouteData.Values)
    {
        routeData.Add(r.Key, r.Value.ToString());
    }

    foreach(var qs in Context.Request.Query)
    {
        routeData.Add(qs.Key, qs.Value);
    }
}

<div class="dropdown">
    <a class="btn-sm btn-default border border-secondary dropdown-toggle" href="#" role="button" id="dropdownLang" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
        @($"{requestCulture.DisplayName}")
    </a>

    <div class="dropdown-menu dropdown-menu-right" aria-labelledby="dropdownLang">
        @foreach (var culture in supportedCultures)
        {
            if (culture.Value.ToLower() != requestCulture.Name.ToLower())
            {
                // replace {culture} value with the one from the list
                routeData["culture"] = culture.Value;

                <a class="dropdown-item small"
                   asp-all-route-data="@routeData">
                    @culture.Text
                </a>
            }
        }
    </div>
</div>

Place the language partial into the top menu bar, insert it right before closing menu list div inside _Layout.cshtml page :

<nav class="navbar navbar-inverse navbar-fixed-top">
    <div class="container">
        <div class="navbar-header">
            <button type="button" class="navbar-toggle" 
                    data-toggle="collapse" data-target=".navbar-collapse">
                <span class="sr-only">Toggle navigation</span>
                <span class="icon-bar"></span>
                <span class="icon-bar"></span>
                <span class="icon-bar"></span>
            </button>
            <a asp-page="/Index" class="navbar-brand">MyTrips</a>
        </div>
        <div class="navbar-collapse collapse">
            <ul class="nav navbar-nav">
                <li><a asp-page="/Index">Home</a></li>
                <li><a asp-page="/Trips" asp-route-culture="@culture">My Trips</a></li>
            </ul>
            <partial name="_LanguagePartial" />
        </div>
    </div>
</nav>

[UPDATE 14.09.2019] Now it is possible to create language navigation menu with a new tag helper using LanguageNavTagHelper.

Add sample output to “Trips.cshtml” page:

@page
@using System.Globalization;

@model MyTrips.Pages.TripsModel
@{
    ViewData["Title"] = "Trips";
}

<h2>Trips</h2>

<p>Current culture : @CultureInfo.CurrentCulture.DisplayName (@CultureInfo.CurrentCulture.NativeName)</p>

<p>Current date : @DateTime.Now</p>

Build and run the application, then navigate to trips page (https://localhost:xxxx/en/trips), you will see the language dropdown on the menubar, change the language and see differences between culture formats.

Next : Localizing Views

Demo Project: My trips application

Source code on github: MyTrips