Multi language database, with default fallback

Question

I have a question that, I know, has been widely discussed about, but in my opinion, there is one aspect that still needs clarification.

I am creating a web-application w

Answer 1

Some notes upfront:

• my answer is more of an addition to my answer to this question, where you added a comment which then led to this question
• in my answer I'm using C# and MS SQL Server (and I'll leave out any OR-mapping specific code)

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In my applications, I use two different approaches for loading multilingual data, depending on the use case:

Administration / CRUD

In the case where the user is entering data or editing existing data (e.g. a product with its translations) I'm using the same approach as you have shown above in your question, e.g:

public class Product
{
    public int ID {get; set;}
    public string SKU {get; set;}
    public IList Translations {get; set;}
}
public class ProductTranslation
{
    public string Language {get; set;}
    public bool IsDefaultLanguage {get; set;}
    public string Title {get; set;}
    public string Description {get; set;}
}

I.e. I'll let the OR-mapper load the product instance(s) with all their translations attached. I then iterate through the translations and pick the ones needed.

Front-end / read-only

In this case, which is mainly front-end code, where I usually just display information to the user (preferably in the user's language), I'm using a different approach:

First of all, I'm using a different data model which doesn't support/know the notion of multiple translations. Instead it is just the representation of a product in the "best" language for the current user:

public class Product
{
    public int ID {get; set;}
    public string SKU {get; set;}

    // language-specific properties
    public string Title {get; set;}
    public string Description {get; set;}
}

To load this data, I'm using different queries (or stored procedures). E.g. to load a product with ID @Id in the language @Language, I'd use the following query:

SELECT
    p.ID,
    p.SKU,
    -- get title, description from the requested translation,
    -- or fall back to the default if not found:
    ISNULL(tr.Title, def.Title) Title,
    ISNULL(tr.Description, def.Description) Description
  FROM Products p
  -- join requested translation, if available:
  LEFT OUTER JOIN ProductTranslations tr
    ON p.ID = tr.ProductId AND tr.Language = @Language
  -- join default language of the product:
  LEFT OUTER JOIN ProductTranslations def
    ON p.ID = def.ProductId AND def.IsDefaultLanguage = 1
  WHERE p.ID = @Id

This returns the product's title and description in the requested language if a translation for that language exists. If no translation exists, the title and description from the default language will be returned.