Introduction

Let's say you have following message description table.

public class DatabaseMessages : MessageDescriptions
{
    /// <summary>Singleton</summary>
    static readonly Lazy<DatabaseMessages> instance = new Lazy<DatabaseMessages>(() => new DatabaseMessages().SetAllReadOnly().SetReadOnly());
    /// <summary>Singleton</summary>
    public static DatabaseMessages Instance => instance.Value;
    /// <summary>Exception factory for http errors</summary>
    static readonly Func<IMessage, Exception> httpExceptionFactory = (IMessage m) => new HttpRequestException(m.Print(), m.Error, (System.Net.HttpStatusCode)m.HttpStatusCode());

    /// <summary>Initialize fields</summary>
    public DatabaseMessages() : base() { this.AddRange(MessageDescriptionsExtensions.FieldReader(this)); }

    /// <summary></summary>
    public readonly IMessageDescription ChannelNotFound = Http(nameof(ChannelNotFound), "Channel '{channel}' is not found-", HttpStatusCode.NotFound);
    /// <summary>User is not authenticated (logged in)</summary>
    public readonly IMessageDescription UserNotAuthenticated = Http(nameof(UserNotAuthenticated), "User is not authenticated.", HttpStatusCode.Forbidden);
    /// <summary>User is not (email) verified</summary>
    public readonly IMessageDescription UserNotConfirmedEmail = Http(nameof(UserNotConfirmedEmail), "User's '{user}' e-mail is not verified.", HttpStatusCode.Forbidden);
    /// <summary>User not found in database</summary>
    public readonly IMessageDescription UserNotFound = Http(nameof(UserNotFound), "User '{user}' is not found.", HttpStatusCode.NotFound);
    /// <summary>User is not subscribed on channel</summary>
    public readonly IMessageDescription UserNotSubscribed = Http(nameof(UserNotSubscribed), "User '{user}' is not subscribed on channel '{channel}'.", HttpStatusCode.Forbidden);

    /// <summary>Create http message</summary>
    public static IMessageDescription Http(string key, string template, HttpStatusCode? httpCode)
    {
        // Create description
        MessageDescription messageDescription = new MessageDescription(key, null, TemplateFormat.BraceAlphaNumeric.Text[template])
            .SetCode(new FNVHash32().HashIn(key))
            .SetHttpStatusCode(httpCode)
            .SetException(httpExceptionFactory);
        // Error
        if (httpCode.HasValue && (int)httpCode.Value >= 300) messageDescription.SetHResult(0x80000000).SetSeverity(MessageLevel.Error);
        // Ok
        else messageDescription.SetHResult(0x00000000).SetSeverity(MessageLevel.Information);
        // Return
        return messageDescription;
    }
}

Table can be added to dependency injection as is.

// Service collection
IServiceCollection serviceCollection = new ServiceCollection()
    .AddSingleton<DatabaseMessages>(DatabaseMessages.Instance);

// Service provider
using var service = serviceCollection.BuildServiceProvider();

// Get messages
DatabaseMessages messages = service.GetRequiredService<DatabaseMessages>();
// Create message
IMessage status = messages.ChannelNotFound.New("00000000-0000-0000-1000-000000000000");
// Print message
WriteLine(status.Print()); // "Channel '00000000-0000-0000-1000-000000000000' is not found"

If service collection has a localization, then initializer delegate is used to apply localization on the table.

// Create localization
ILocalization localization = new Localization()
    .AddLine("fi", "ChannelNotFound", "Detect", "Kanavaa {channelId} ei löytyny")
    .AddLine("fi", "UserNotAuthenticated", "Detect", "Käyttäjä ei ole kirjautunut")
    .AddLine("fi", "UserNotConfirmedEmail", "Detect", "Käyttäjän \"{user}\" sähköposti ei ole varmistettu.")
    .AddLine("fi", "UserNotFound", "Detect", "Käyttäjää {channelId} ei löytyny")
    .AddLine("fi", "UserNotSubscribed", "Detect", "Käyttäjä {user} ei ole tilannut kanavaa {channel}.");
// Service collection
IServiceCollection serviceCollection = new ServiceCollection()
    .AddSingleton<ILocalization>(localization)
    .AddSingleton<DatabaseMessages>(
        sp => new DatabaseMessages()
                .LocalizeMessages(sp.GetRequiredService<ILocalization>())
                .SetAllReadOnly()
                .SetReadOnly()
    );

// Service provider
using var service = serviceCollection.BuildServiceProvider();

// Get messages
DatabaseMessages messages = service.GetRequiredService<DatabaseMessages>();
// Create status object
IMessage status = messages.ChannelNotFound.New("00000000-0000-0000-1000-000000000000");
// Print status in "fi"
WriteLine(status.Print(CultureInfo.GetCultureInfo("fi"))); // "Kanavaa '00000000-0000-0000-1000-000000000000' ei löytyny"

If error message is forwarded to user interface, the display text need to be localized from exception.

try
{
    // User was not found
    messages.UserNotFound.Throw("00000000-0000-0000-1000-000000000000");
} catch (HttpRequestException e)
{
    // Choose culture
    CultureInfo fi = CultureInfo.GetCultureInfo("fi");
    // Print unlocalized and localized messages
    string unlocalized = e.Message;
    string localized = e.AttachedMessage()?.Print(fi) ?? e.Message;
    // Print
    WriteLine(unlocalized); // "User '00000000-0000-0000-1000-000000000000' is not found"
    WriteLine(localized  ); // "Käyttäjää '00000000-0000-0000-1000-000000000000' ei löytynyt"
}

Messages can be localized to use active culture from ICultureProvider.

// Create localization
ILocalization localization = new Localization()
    .AddLine("fi", "ChannelNotFound", "Detect", "Kanavaa '{channel}' ei löytyny")
    .AddLine("fi", "UserNotAuthenticated", "Detect", "Käyttäjä ei ole kirjautunut")
    .AddLine("fi", "UserNotConfirmedEmail", "Detect", "Käyttäjän '{user}' sähköpostia ei ole varmistettu.")
    .AddLine("fi", "UserNotFound", "Detect", "Käyttäjää '{channel}' ei löytyny")
    .AddLine("fi", "UserNotSubscribed", "Detect", "Käyttäjä '{user}' ei ole tilannut kanavaa '{channel}'.");
// Choose culture provider (Asp.Net uses Thread.CurrentThread.CurrentCulture)
ICultureProvider cultureProvider = CultureProvider.CurrentThread.Instance;
// Service collection
IServiceCollection serviceCollection = new ServiceCollection()
    .AddSingleton<ILocalization>(localization)
    .AddSingleton<DatabaseMessages>(
        sp => new DatabaseMessages()
                .LocalizeMessages(
                    localization: sp.GetRequiredService<ILocalization>(),
                    cultureProvider: cultureProvider)
                .SetAllReadOnly()
                .SetReadOnly()
     );

// Service provider
using var service = serviceCollection.BuildServiceProvider();

// Assign language
Thread.CurrentThread.CurrentUICulture = CultureInfo.GetCultureInfo("fi-FI");
// Assign number and date formats
Thread.CurrentThread.CurrentCulture = CultureInfo.GetCultureInfo("fi-FI");

// Get messages
DatabaseMessages messages = service.GetRequiredService<DatabaseMessages>();
// Create status object
IMessage status = messages.ChannelNotFound.New("00000000-0000-0000-1000-000000000000");
// Print in CurrentUICulture (language) + CurrentCulture (units)
WriteLine(status); // "Kanavaa '00000000-0000-0000-1000-000000000000 'ei löytyny"
// Print with fallback culture
WriteLine(status.Print(CultureInfo.InvariantCulture)); // "Channel '00000000-0000-0000-1000-000000000000' is not found"

try
{
    // User was not found
    messages.UserNotFound.Throw("00000000-0000-0000-1000-000000000000");
} catch (HttpRequestException e)
{
    WriteLine(e.Message); // "Käyttäjää '00000000-0000-0000-1000-000000000000' ei löytynyt"
    WriteLine(e.AttachedMessage()!.Print(CultureInfo.InvariantCulture)); // "Channel '00000000-0000-0000-1000-000000000000' is not found"
}

Full Example

Full example

using System.Globalization;
using System.Net;
using Avalanche.Localization;
using Avalanche.Message;
using Avalanche.Template;
using Avalanche.Utilities;
using Microsoft.Extensions.DependencyInjection;
using static System.Console;

public class di
{
    public static void Run()
    {
        {
            // <01>
            // Service collection
            IServiceCollection serviceCollection = new ServiceCollection()
                .AddSingleton<DatabaseMessages>(DatabaseMessages.Instance);

            // Service provider
            using var service = serviceCollection.BuildServiceProvider();

            // Get messages
            DatabaseMessages messages = service.GetRequiredService<DatabaseMessages>();
            // Create message
            IMessage status = messages.ChannelNotFound.New("00000000-0000-0000-1000-000000000000");
            // Print message
            WriteLine(status.Print()); // "Channel '00000000-0000-0000-1000-000000000000' is not found"
            // </01>
        }
        {
            // <02>
            // Create localization
            ILocalization localization = new Localization()
                .AddLine("fi", "ChannelNotFound", "Detect", "Kanavaa {channelId} ei löytyny")
                .AddLine("fi", "UserNotAuthenticated", "Detect", "Käyttäjä ei ole kirjautunut")
                .AddLine("fi", "UserNotConfirmedEmail", "Detect", "Käyttäjän \"{user}\" sähköposti ei ole varmistettu.")
                .AddLine("fi", "UserNotFound", "Detect", "Käyttäjää {channelId} ei löytyny")
                .AddLine("fi", "UserNotSubscribed", "Detect", "Käyttäjä {user} ei ole tilannut kanavaa {channel}.");
            // Service collection
            IServiceCollection serviceCollection = new ServiceCollection()
                .AddSingleton<ILocalization>(localization)
                .AddSingleton<DatabaseMessages>(
                    sp => new DatabaseMessages()
                            .LocalizeMessages(sp.GetRequiredService<ILocalization>())
                            .SetAllReadOnly()
                            .SetReadOnly()
                );

            // Service provider
            using var service = serviceCollection.BuildServiceProvider();

            // Get messages
            DatabaseMessages messages = service.GetRequiredService<DatabaseMessages>();
            // Create status object
            IMessage status = messages.ChannelNotFound.New("00000000-0000-0000-1000-000000000000");
            // Print status in "fi"
            WriteLine(status.Print(CultureInfo.GetCultureInfo("fi"))); // "Kanavaa '00000000-0000-0000-1000-000000000000' ei löytyny"
            // </02>
            // <03>
            try
            {
                // User was not found
                messages.UserNotFound.Throw("00000000-0000-0000-1000-000000000000");
            } catch (HttpRequestException e)
            {
                // Choose culture
                CultureInfo fi = CultureInfo.GetCultureInfo("fi");
                // Print unlocalized and localized messages
                string unlocalized = e.Message;
                string localized = e.AttachedMessage()?.Print(fi) ?? e.Message;
                // Print
                WriteLine(unlocalized); // "User '00000000-0000-0000-1000-000000000000' is not found"
                WriteLine(localized  ); // "Käyttäjää '00000000-0000-0000-1000-000000000000' ei löytynyt"
            }
            // </03>
        }
        {
            // <04>
            // Create localization
            ILocalization localization = new Localization()
                .AddLine("fi", "ChannelNotFound", "Detect", "Kanavaa '{channel}' ei löytyny")
                .AddLine("fi", "UserNotAuthenticated", "Detect", "Käyttäjä ei ole kirjautunut")
                .AddLine("fi", "UserNotConfirmedEmail", "Detect", "Käyttäjän '{user}' sähköpostia ei ole varmistettu.")
                .AddLine("fi", "UserNotFound", "Detect", "Käyttäjää '{channel}' ei löytyny")
                .AddLine("fi", "UserNotSubscribed", "Detect", "Käyttäjä '{user}' ei ole tilannut kanavaa '{channel}'.");
            // Choose culture provider (Asp.Net uses Thread.CurrentThread.CurrentCulture)
            ICultureProvider cultureProvider = CultureProvider.CurrentThread.Instance;
            // Service collection
            IServiceCollection serviceCollection = new ServiceCollection()
                .AddSingleton<ILocalization>(localization)
                .AddSingleton<DatabaseMessages>(
                    sp => new DatabaseMessages()
                            .LocalizeMessages(
                                localization: sp.GetRequiredService<ILocalization>(),
                                cultureProvider: cultureProvider)
                            .SetAllReadOnly()
                            .SetReadOnly()
                 );

            // Service provider
            using var service = serviceCollection.BuildServiceProvider();

            // Assign language
            Thread.CurrentThread.CurrentUICulture = CultureInfo.GetCultureInfo("fi-FI");
            // Assign number and date formats
            Thread.CurrentThread.CurrentCulture = CultureInfo.GetCultureInfo("fi-FI");

            // Get messages
            DatabaseMessages messages = service.GetRequiredService<DatabaseMessages>();
            // Create status object
            IMessage status = messages.ChannelNotFound.New("00000000-0000-0000-1000-000000000000");
            // Print in CurrentUICulture (language) + CurrentCulture (units)
            WriteLine(status); // "Kanavaa '00000000-0000-0000-1000-000000000000 'ei löytyny"
            // Print with fallback culture
            WriteLine(status.Print(CultureInfo.InvariantCulture)); // "Channel '00000000-0000-0000-1000-000000000000' is not found"

            try
            {
                // User was not found
                messages.UserNotFound.Throw("00000000-0000-0000-1000-000000000000");
            } catch (HttpRequestException e)
            {
                WriteLine(e.Message); // "Käyttäjää '00000000-0000-0000-1000-000000000000' ei löytynyt"
                WriteLine(e.AttachedMessage()!.Print(CultureInfo.InvariantCulture)); // "Channel '00000000-0000-0000-1000-000000000000' is not found"
            }
            // </04>
        }
    }
    // <100>
    public class DatabaseMessages : MessageDescriptions
    {
        /// <summary>Singleton</summary>
        static readonly Lazy<DatabaseMessages> instance = new Lazy<DatabaseMessages>(() => new DatabaseMessages().SetAllReadOnly().SetReadOnly());
        /// <summary>Singleton</summary>
        public static DatabaseMessages Instance => instance.Value;
        /// <summary>Exception factory for http errors</summary>
        static readonly Func<IMessage, Exception> httpExceptionFactory = (IMessage m) => new HttpRequestException(m.Print(), m.Error, (System.Net.HttpStatusCode)m.HttpStatusCode());

        /// <summary>Initialize fields</summary>
        public DatabaseMessages() : base() { this.AddRange(MessageDescriptionsExtensions.FieldReader(this)); }

        /// <summary></summary>
        public readonly IMessageDescription ChannelNotFound = Http(nameof(ChannelNotFound), "Channel '{channel}' is not found-", HttpStatusCode.NotFound);
        /// <summary>User is not authenticated (logged in)</summary>
        public readonly IMessageDescription UserNotAuthenticated = Http(nameof(UserNotAuthenticated), "User is not authenticated.", HttpStatusCode.Forbidden);
        /// <summary>User is not (email) verified</summary>
        public readonly IMessageDescription UserNotConfirmedEmail = Http(nameof(UserNotConfirmedEmail), "User's '{user}' e-mail is not verified.", HttpStatusCode.Forbidden);
        /// <summary>User not found in database</summary>
        public readonly IMessageDescription UserNotFound = Http(nameof(UserNotFound), "User '{user}' is not found.", HttpStatusCode.NotFound);
        /// <summary>User is not subscribed on channel</summary>
        public readonly IMessageDescription UserNotSubscribed = Http(nameof(UserNotSubscribed), "User '{user}' is not subscribed on channel '{channel}'.", HttpStatusCode.Forbidden);

        /// <summary>Create http message</summary>
        public static IMessageDescription Http(string key, string template, HttpStatusCode? httpCode)
        {
            // Create description
            MessageDescription messageDescription = new MessageDescription(key, null, TemplateFormat.BraceAlphaNumeric.Text[template])
                .SetCode(new FNVHash32().HashIn(key))
                .SetHttpStatusCode(httpCode)
                .SetException(httpExceptionFactory);
            // Error
            if (httpCode.HasValue && (int)httpCode.Value >= 300) messageDescription.SetHResult(0x80000000).SetSeverity(MessageLevel.Error);
            // Ok
            else messageDescription.SetHResult(0x00000000).SetSeverity(MessageLevel.Information);
            // Return
            return messageDescription;
        }
    }
    // </100>

}