abp/docs/en/multi-lingual-entities.md

//[doc-seo]
{
    "Description": "Use ABP multi-lingual objects to select translations by culture, apply fallback rules, and process translations in bulk."
}

Multi-Lingual Objects

The Volo.Abp.MultiLingualObject package provides a contract and a selection service for objects that store one translation per language. Persistence mapping is application-specific; the package does not create a database relationship for the translations.

Installation

Install the package in the project that defines the consuming module:

abp add-package Volo.Abp.MultiLingualObject

Add AbpMultiLingualObjectsModule as a dependency of that module when the package is installed manually:

[DependsOn(typeof(AbpMultiLingualObjectsModule))]
public class MyApplicationModule : AbpModule
{
}

Define a Multi-Lingual Object

Implement IMultiLingualObject<TTranslation> on the object and IObjectTranslation on its translation type:

using Volo.Abp.MultiLingualObjects;

public class Product : IMultiLingualObject<ProductTranslation>
{
    public ICollection<ProductTranslation> Translations { get; set; } =
        new List<ProductTranslation>();
}

public class ProductTranslation : IObjectTranslation
{
    public string Language { get; set; } = string.Empty;

    public string Name { get; set; } = string.Empty;
}

Language stores a culture name such as en, en-US or tr.

Select a Translation

Inject IMultiLingualObjectManager and call GetTranslationAsync:

public class ProductService
    : ITransientDependency
{
    private readonly IMultiLingualObjectManager _multiLingualObjectManager;

    public ProductService(
        IMultiLingualObjectManager multiLingualObjectManager)
    {
        _multiLingualObjectManager = multiLingualObjectManager;
    }

    public Task<ProductTranslation?> GetTranslationAsync(Product product)
    {
        return _multiLingualObjectManager
            .GetTranslationAsync<Product, ProductTranslation>(product);
    }
}

With the default arguments, the manager uses CultureInfo.CurrentUICulture.Name. It selects translations in this order:

1. An exact translation for the current UI culture.
2. A translation for a parent of the current UI culture when fallbackToParentCultures is true.
3. A translation for the language configured by LocalizationSettingNames.DefaultLanguage.
4. The first available translation.

The method returns null when the collection is null or empty. To disable only the parent-culture fallback, pass culture and set fallbackToParentCultures to false. The default-language and first-available fallbacks still apply.

Select Translations in Bulk

Use GetBulkTranslationsAsync to select translations for multiple objects with the same culture and fallback settings:

var results = await _multiLingualObjectManager
    .GetBulkTranslationsAsync<Product, ProductTranslation>(products);

foreach (var (product, translation) in results)
{
    // Use product and its selected translation.
}

Each result keeps the source object together with its selected translation. An object with no translations gets a null translation.