Create Multi-language Enum In EF Core?

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Introduction

Enums are a fundamental concept in programming, allowing us to define a set of named values. However, when working with multiple languages, a single enum value may not be sufficient. In this article, we will explore how to create a multi-language enum in Entity Framework Core (EF Core) and persist these values into the database.

Problem Statement

Let's consider a simple example where we have an enum called OrderStatus with values like New, InProgress, and Completed. However, we want to support multiple languages, including English and French. We can add the French name for the enum property in the Description attribute, but how do we persist these values into the database and use them to show in ASP.NET UI?

Solution Overview

To create a multi-language enum in EF Core, we will use a combination of the following approaches:

  1. Use a separate table for enum values: Instead of storing enum values in a single table, we will create a separate table to store the enum values for each language.
  2. Use a bridge table to map enum values to the main table: We will create a bridge table to map the enum values to the main table, allowing us to persist the values in the database.
  3. Use EF Core's built-in support for enums: We will use EF Core's built-in support for enums to map the enum values to the database.

Step 1: Create a Separate Table for Enum Values

First, let's create a separate table to store the enum values for each language. We will create a table called OrderStatusValues with columns for the enum value, language code, and the value in the respective language.

public class OrderStatusValue
{
    public int Id { get; set; }
    public string LanguageCode { get; set; }
    public string Value { get; set; }
}

Step 2: Create a Bridge Table to Map Enum Values to the Main Table

Next, let's create a bridge table to map the enum values to the main table. We will create a table called OrderStatuses with columns for the order status ID, language code, and the corresponding enum value.

public class OrderStatus
{
    public int Id { get; set; }
    public string LanguageCode { get; set; }
    public OrderStatusValue OrderStatusValue { get; set; }
}

Step 3: Use EF Core's Built-in Support for Enums

Now, let's use EF Core's built-in support for enums to map the enum values to the database. We will create a class called OrderStatusEnum that inherits from Enum and uses the OrderStatusValue class to map the enum values.

public enum OrderStatusEnum
{
    [Description("New", "Nouveau")]
    New,
    [Description("InProgress", "En cours")]
    InProgress,
    [Description("Completed", "Terminé")]
    Completed
}

Step 4: Configure EF Core to Use the Multi-Language Enum

Finally, let's configure EF Core to use the multi-language enum. We will create a DbContext class that includes the OrderStatus and OrderStatusValue classes.

public class MyDbContext : DbContext
{
    public DbSet<OrderStatus> OrderStatuses { get; set; }
    public DbSet<OrderStatusValue> OrderStatusValues { get; set; }

protected override void OnModelCreating(ModelBuilder modelBuilder)
{
    modelBuilder.Entity&lt;OrderStatus&gt;()
        .HasOne(os =&gt; os.OrderStatusValue)
        .WithMany(osv =&gt; osv.OrderStatuses)
        .HasForeignKey(os =&gt; os.Id);

    modelBuilder.Entity&lt;OrderStatusValue&gt;()
        .HasIndex(osv =&gt; osv.LanguageCode)
        .IsUnique();
}



}

Conclusion

In this article, we explored how to create a multi-language enum in Entity Framework Core (EF Core) and persist these values into the database. We used a combination of a separate table for enum values, a bridge table to map enum values to the main table, and EF Core's built-in support for enums to achieve this. By following these steps, you can create a multi-language enum in EF Core and use it to show in ASP.NET UI.

Example Use Case

Here's an example use case where we use the multi-language enum to display the order status in the UI:

public class OrderStatusController : Controller
{
    private readonly MyDbContext _context;

public OrderStatusController(MyDbContext context)
{
    _context = context;
}

public IActionResult Index()
{
    var orderStatuses = _context.OrderStatuses
        .Include(os =&gt; os.OrderStatusValue)
        .ToList();

    return View(orderStatuses);
}



}

In the Index action, we retrieve the list of order statuses from the database and include the corresponding enum value for each language. We then pass the list to the view, where we can display the order status in the UI.

public class OrderStatusViewModel
{
    public int Id { get; set; }
    public string LanguageCode { get; set; }
    public string Value { get; set; }
}

public class OrderStatusesViewModel
{
public List<OrderStatusViewModel> OrderStatuses { get; set; }
}


public class OrderStatusesController : Controller
{
public IActionResult Index()
{
var orderStatuses = new OrderStatusesViewModel
{
OrderStatuses = new List<OrderStatusViewModel>
{
new OrderStatusViewModel { Id = 1, LanguageCode = "en", Value = "New" },
new OrderStatusViewModel { Id = 2, LanguageCode = "fr", Value = "Nouveau" },
new OrderStatusViewModel { Id = 3, LanguageCode = "en", Value = "InProgress" },
new OrderStatusViewModel { Id = 4, LanguageCode = "fr", Value = "En cours" },
new OrderStatusViewModel { Id = 5, LanguageCode = "en", Value = "Completed" },
new OrderStatusViewModel { Id = 6, LanguageCode = "fr", Value = "Terminé" }
}
};


    return View(orderStatuses);
}



}

In the Index action, we create a new instance of the OrderStatusesViewModel class and populate it with the list of order statuses. We then pass the view model to the view, where we can display the order status in the UI.

@model OrderStatusesViewModel

<h2>Order Statuses</h2>


<table>
<thead>
<tr>
<th>Id</th>
<th>Language Code</th>
<th>Value</th>
</tr>
</thead>
<tbody>
@foreach (var orderStatus in Model.OrderStatuses)
{
<tr>
<td>@orderStatus.Id</td>
<td>@orderStatus.LanguageCode</td>
<td>@orderStatus.Value</td>
</tr>
}
</tbody>
</table>

In the view, we use a foreach loop to iterate over the list of order statuses and display the ID, language code, and value for each order status.

Introduction

In our previous article, we explored how to create a multi-language enum in Entity Framework Core (EF Core) and persist these values into the database. In this article, we will answer some frequently asked questions (FAQs) related to creating a multi-language enum in EF Core.

Q: Why do I need a separate table for enum values?

A: You need a separate table for enum values to store the values for each language. This allows you to persist the values in the database and use them to show in ASP.NET UI.

Q: How do I configure EF Core to use the multi-language enum?

A: To configure EF Core to use the multi-language enum, you need to create a DbContext class that includes the OrderStatus and OrderStatusValue classes. You also need to configure the relationships between the tables using the HasOne and WithMany methods.

Q: Can I use a single table to store enum values for all languages?

A: No, you cannot use a single table to store enum values for all languages. This is because each language has its own set of values, and using a single table would require you to store duplicate values for each language.

Q: How do I handle enum values that are not translated?

A: To handle enum values that are not translated, you can use a default value for the language code. For example, you can use the language code "en" (English) as the default value.

Q: Can I use a different data type for the enum value?

A: Yes, you can use a different data type for the enum value. For example, you can use a string data type instead of an integer data type.

Q: How do I handle enum values that are deleted or updated?

A: To handle enum values that are deleted or updated, you need to update the corresponding enum value in the OrderStatus table. You can use the Update method to update the enum value.

Q: Can I use a different database provider for the multi-language enum?

A: Yes, you can use a different database provider for the multi-language enum. For example, you can use the SQL Server database provider instead of the Entity Framework Core database provider.

Q: How do I handle enum values that are not persisted in the database?

A: To handle enum values that are not persisted in the database, you need to use the Include method to include the enum value in the query. You can also use the AsNoTracking method to disable tracking for the enum value.

Q: Can I use a different framework for the multi-language enum?

A: Yes, you can use a different framework for the multi-language enum. For example, you can use the ASP.NET Core framework instead of the Entity Framework Core framework.

Conclusion

In this article, we answered some frequently asked questions (FAQs) related to creating a multi-language enum in Entity Framework Core (EF Core). We hope this article helps you to better understand how to create a multi enum in EF Core and use it to show in ASP.NET UI.

Example Use Case

Here's an example use case where we use the multi-language enum to display the order status in the UI:

public class OrderStatusController : Controller
{
    private readonly MyDbContext _context;

public OrderStatusController(MyDbContext context)
{
    _context = context;
}

public IActionResult Index()
{
    var orderStatuses = _context.OrderStatuses
        .Include(os =&gt; os.OrderStatusValue)
        .ToList();

    return View(orderStatuses);
}



}

In the Index action, we retrieve the list of order statuses from the database and include the corresponding enum value for each language. We then pass the list to the view, where we can display the order status in the UI.

public class OrderStatusViewModel
{
    public int Id { get; set; }
    public string LanguageCode { get; set; }
    public string Value { get; set; }
}

public class OrderStatusesViewModel
{
public List<OrderStatusViewModel> OrderStatuses { get; set; }
}


public class OrderStatusesController : Controller
{
public IActionResult Index()
{
var orderStatuses = new OrderStatusesViewModel
{
OrderStatuses = new List<OrderStatusViewModel>
{
new OrderStatusViewModel { Id = 1, LanguageCode = "en", Value = "New" },
new OrderStatusViewModel { Id = 2, LanguageCode = "fr", Value = "Nouveau" },
new OrderStatusViewModel { Id = 3, LanguageCode = "en", Value = "InProgress" },
new OrderStatusViewModel { Id = 4, LanguageCode = "fr", Value = "En cours" },
new OrderStatusViewModel { Id = 5, LanguageCode = "en", Value = "Completed" },
new OrderStatusViewModel { Id = 6, LanguageCode = "fr", Value = "Terminé" }
}
};


    return View(orderStatuses);
}



}

In the Index action, we create a new instance of the OrderStatusesViewModel class and populate it with the list of order statuses. We then pass the view model to the view, where we can display the order status in the UI.

@model OrderStatusesViewModel

<h2>Order Statuses</h2>


<table>
<thead>
<tr>
<th>Id</th>
<th>Language Code</th>
<th>Value</th>
</tr>
</thead>
<tbody>
@foreach (var orderStatus in Model.OrderStatuses)
{
<tr>
<td>@orderStatus.Id</td>
<td>@orderStatus.LanguageCode</td>
<td>@orderStatus.Value</td>
</tr>
}
</tbody>
</table>

In the view, we use a foreach loop to iterate over the list of order statuses and display the ID, language code, and value for each order status.

By following these steps, you can create a multi-language enum in Entity Framework Core (EF Core) and use it to show in ASP.NET UI.