Question

使用DBContext（如

）时，EF5是否可能不会立即关闭连接

 public void UpdateCategory(Models.Category catData)
    {
        if (catData == null) return;
        using (var cntx = new DataContext())
        {
            //IN THE LINE BELOW A CONNECTION IS DEFINITELY OPENED BUT IS IT IMMEDIATELY CLOSE????
            var cat = cntx.Set<Category>().FirstOrDefault(c => c.CategoryId == catData.CategoryId);

            if (cat == null) return;

            if (!cat.LastChanged.Matches(catData.LastChanged))
                throw new ConcurrencyException(cat.GetType().ToString());

            cat.CategoryName = catData.CategoryName;

            cntx.DbContext.Entry<Category>(cat).State = System.Data.EntityState.Modified;

            //AFTER THE NEXT LINE DO I HAVE 2 CONNECTIONS OPENED? OR WAS THE CONNECTION OPENED FROM THE FIRST QUERY CLOSED ALREADY?
            cntx.SaveChanges();


            catData.LastChanged = cat.LastChanged;
        }

    }

是否有相同的上下文创建的scenerios \ bugs \打开2个连接，一个打开？

Answer 1

如果您在此处查看MSDN：http://msdn.microsoft.com/library/vstudio/bb896325

实体框架仅在需要时打开连接，例如执行查询或调用SaveChanges，然后在操作完成时关闭连接。

当调用查询方法时，将打开连接，并且它将保持打开状态，直到完全使用或丢弃ObjectResult为止。

public void UpdateCategory(Models.Category catData)
{
    if (catData == null) return;
    using (var cntx = new DataContext())
    {
        //IN THE LINE BELOW A CONNECTION IS DEFINITELY OPENED BUT IS IT 
        //IMMEDIATELY CLOSE? => YES!
        var cat = cntx.Set<Category>()
                          .FirstOrDefault(c => c.CategoryId == catData.CategoryId);

        if (cat == null) return;

        if (!cat.LastChanged.Matches(catData.LastChanged))
            throw new ConcurrencyException(cat.GetType().ToString());

        cat.CategoryName = catData.CategoryName;

        cntx.DbContext.Entry<Category>(cat).State = System.Data.EntityState.Modified;

        //AFTER THE NEXT LINE DO I HAVE 2 CONNECTIONS OPENED? => NO
        cntx.SaveChanges();


        catData.LastChanged = cat.LastChanged;
    }

}

是否有相同上下文创建的场景\打开2个连接，一个打开？

是的，当使用带有DbContext的事务时，它将打开第二个连接，看看这里：http://www.digitallycreated.net/Blog/48/entity-framework-transactionscope-and-msdtc

EF 5连接管理

1 个答案: