实体框架中内容的国际化

Question

public class FooEntity
{
  public long Id { get; set; }
  public string Code { get; set; } // Some values might not need i18n
  public string Name { get; set } // but e.g. this needs internationalized
  public string Description { get; set; } // and this too
}

1）在db中存储资源密钥

public class FooEntity
{
  ...
  public string NameKey { get; set; }
  public string DescriptionKey { get; set; }
}

• 优点：不需要复杂的查询来获得已翻译的实体。system.globalization为您处理后退。
• 缺点：管理员用户很难管理翻译（每当我的fo更改时，必须部署资源文件）。

2）使用LocalizableString实体类型

public class FooEntity
{
  ...

  public int NameId { get; set; }
  public virtual LocalizableString Name { get; set; }

  public int NameId { get; set; }
  public virtual LocalizableString Description { get; set; }
}

public class LocalizableString
{
  public int Id { get; set; }

  public ICollection<LocalizedString> LocalizedStrings { get; set; }
}

public class LocalizedString
{
  public int Id { get; set; }

  public int ParentId { get; set; }
  public virtual LocalizableString Parent { get; set; }

  public int LanguageId { get; set; }
  public virtual Language Language { get; set; }

  public string Value { get; set; }
}

public class Language
{
  public int Id { get; set; }
  public string Name { get; set; }
  public string CultureCode { get; set; }
}

null

public class FooEntity
{
  ...
  public ICollection<FooTranslation> Translations { get; set; }
}

public class FooTranslation
{
  public long Id { get; set; }

  public int ParentId { get; set; }
  public virtual FooEntity Parent { get; set; }

  public int LanguageId { get; set; }
  public virtual Language Language { get; set; }

  public string Name { get; set }
  public string Description { get; set; }
}

public class Language
{
  public int Id { get; set; }
  public string Name { get; set; }
  public string CultureCode { get; set; }
}

null

Answer 1

你为什么不两全其美呢？拥有一个CustomResourceManager来处理资源的加载和选择正确的区域性，并使用一个CustomResourceReader来使用您喜欢的任何后备存储。一个基本的实现可能是这样的，它依赖于Resourceky的约定，即TypeName_PropertyName_PropertyValue。如果由于某种原因需要更改backingstore的结构（CSV/Excel/MSSQL/Table结构），则只需要更改ResourceReader的实现。

作为额外的奖励，我还得到了真实的/透明的代理。

资源管理器

class MyRM:ResourceManager
{
    readonly Dictionary<CultureInfo, ResourceSet>  sets = new Dictionary<CultureInfo, ResourceSet>();


    public void UnCache(CultureInfo ci)
    {
        sets.Remove(ci):
    }

    protected override ResourceSet InternalGetResourceSet(CultureInfo culture, bool createIfNotExists, bool tryParents)
    {
        ResourceSet set;
        if (!sets.TryGetValue(culture, out set))
        {
            IResourceReader rdr = new MyRR(culture);
            set = new ResourceSet(rdr);
            sets.Add(culture,set);
        }
        return set; 
    }

    // sets Localized values on properties
    public T GetEntity<T>(T obj)
    {
        var entityType = typeof(T);
        foreach (var prop in entityType.GetProperties(
                    BindingFlags.Instance   
                    | BindingFlags.Public)
            .Where(p => p.PropertyType == typeof(string) 
                && p.CanWrite 
                && p.CanRead))
        {
            // FooEntity_Name_(content of Name field)
            var key = String.Format("{0}_{1}_{2}", 
                entityType.Name, 
                prop.Name, 
                prop.GetValue(obj,null));

            var val = GetString(key);
            // only set if a value was found
            if (!String.IsNullOrEmpty(val))
            {
                prop.SetValue(obj, val, null);
            }
        }
        return obj;
    }
}

class MyRR:IResourceReader
{
    private readonly Dictionary<string, string> _dict;

    public MyRR(CultureInfo ci)
    {
        _dict = new Dictionary<string, string>();
        // get from some storage (here a hardcoded Dictionary)
        // You have to be able to deliver a IDictionaryEnumerator
        switch (ci.Name)
        {
            case "nl-NL":
                _dict.Add("FooEntity_Name_Dutch", "nederlands");
                _dict.Add("FooEntity_Name_German", "duits");
                break;
            case "en-US":
                _dict.Add("FooEntity_Name_Dutch", "The Netherlands");
                break;
            case "en":
                _dict.Add("FooEntity_Name_Dutch", "undutchables");
                _dict.Add("FooEntity_Name_German", "german");
                break;
            case "": // invariant
                _dict.Add("FooEntity_Name_Dutch", "dutch");
                _dict.Add("FooEntity_Name_German", "german?");
                break;
            default:
                Trace.WriteLine(ci.Name+" has no resources");
                break;
        }

    }

    public System.Collections.IDictionaryEnumerator GetEnumerator()
    {
        return _dict.GetEnumerator();
    }
    // left out not implemented interface members
  }

var rm = new MyRM(); 

var f = new FooEntity();
f.Name = "Dutch";
var fl = rm.GetEntity(f);
Console.WriteLine(f.Name);

Thread.CurrentThread.CurrentUICulture = new CultureInfo("nl-NL");

f.Name = "Dutch";
var dl = rm.GetEntity(f);
Console.WriteLine(f.Name);

public class Localizer<T>: RealProxy
{
    MyRM rm = new MyRM();
    private T obj; 

    public Localizer(T o)
        : base(typeof(T))
    {
        obj = o;
    }

    public override IMessage Invoke(IMessage msg)
    {
        var meth = msg.Properties["__MethodName"].ToString();
        var bf = BindingFlags.Public | BindingFlags.Instance ;
        if (meth.StartsWith("set_"))
        {
            meth = meth.Substring(4);
            bf |= BindingFlags.SetProperty;
        }
        if (meth.StartsWith("get_"))
        {
           // get the value...
            meth = meth.Substring(4);
            var key = String.Format("{0}_{1}_{2}",
                                    typeof (T).Name,
                                    meth,
                                    typeof (T).GetProperty(meth, BindingFlags.Public | BindingFlags.Instance
        |BindingFlags.GetProperty).
        GetValue(obj, null));
            // but use it for a localized lookup (rm is the ResourceManager)
            var val = rm.GetString(key);
            // return the localized value
            return new ReturnMessage(val, null, 0, null, null);
        }
        var args = new object[0];
        if (msg.Properties["__Args"] != null)
        {
            args = (object[]) msg.Properties["__Args"];
        }
        var res = typeof (T).InvokeMember(meth, 
            bf
            , null, obj, args);
        return new ReturnMessage(res, null, 0, null, null);
    }
}

 var f = new FooEntity();
 f.Name = "Dutch";
 var l = new Localizer<FooEntity>(f);
 var fp = (FooEntity) l.GetTransparentProxy();
 fp.Name = "Dutch"; // notice you can use the proxy as is,
                    // it updates the actual FooEntity
 var localizedValue = fp.Name;