从循环中调用数据访问方法时如何重用 EF 数据上下文

Question

给定数据访问对象Data以及从foreach循环调用具有签名public void GetEntityAttributesValues(int sessId, int entId)的数据访问对象的方法，重用 EF 数据上下文而不是为循环中的每个调用创建它的最佳方法是什么？

圈：

foreach (var ord in Data.Entities.Where(m => m.SessionId == CurrentSessionId))
    {
        Data.GetEntityAttributesValues(sid, ord.Id);
        ...
    }

方法：

    public void GetEntityAttributesValues(int sessId, int entId)
    {
        var tsOptions = new TransactionOptions { IsolationLevel = IsolationLevel.ReadUncommitted };
        using (var scope = new TransactionScope(TransactionScopeOption.Required, tsOptions))
        {
            using (var context = new MyDataEntities(MyDataConnection))
            {
                var attVals = context.OrderAttributeValues.Where(a => a.SessionId == sessId
                    && a.OrderId == entId).ToList();
                foreach (var attVal in attVals)
                {
                    var att = Attributes.Single(a => a.Key == attVal.AttributeId);
                    AttributeValues[att.Value] = attVal.AttributeValue;
                }
                scope.Complete();
            }
        }
    }

因此，与其每次从循环调用此方法时都在使用块中创建新上下文，不如重用数据上下文......

Answer 1

我认为使用数据上下文的最佳方法是同时使用 IoC 和存储库模式，在设置 IoC 类结构映射 （ https://github.com/webadvanced/Structuremap-MVC3 ） 后，您可以像这样使用存储库：

public class DatabaseFactory : Disposable, IDatabaseFactory 
{
    private DatabaseContext _database;
    public DatabaseContext Get() {
        return _database ?? (_database = new DatabaseContext());
    }
    protected override void DisposeCore() {
        if (_database != null)
            _database.Dispose();
    }
}

和

public class FooRepository : IFooRepository {
    private readonly DatabaseContext _database;
    private readonly IDatabaseFactory _databaseFactory;
    private readonly IDbSet<Foo> _dbset;
    public MyRepository (IDatabaseFactory databaseFactory) {
        _databaseFactory = databaseFactory;
        _database = _database ?? (_database = _databaseFactory.Get());
        _dbset = _database.Set<Foo>();
    }
    protected DatabaseContext Database {
        get { return _database; }
    }
    public virtual void Add(Foo entity) {
        _dbset.Add(entity);
    }

}