Question

之间有什么区别？ MyEntities.AsNoTracking() 和 context.MyEntities.MergeOption = MergeOption.NoTracking; ？

我从第二个推荐here中获取了合并选项，但我还没有真正找到它。我怀疑＆＃34; MergeOption＆＃34;从那时起，微软就删除了这件事。

Answer 1

AsNoTracking只是MergeOption.NoTracking ObjectContext / ObjectSet版本（EF 4及以下版本）的DbContext / DbSet版本（EF 4.1及以上版本）。

AsNoTracking实施：

public static IQueryable AsNoTracking(this IQueryable source)
        {
            Check.NotNull(source, "source");

            var asDbQuery = source as DbQuery;
            return asDbQuery != null ? asDbQuery.AsNoTracking() : CommonAsNoTracking(source);
        }

CommonAsNoTracking实施：

private static T CommonAsNoTracking<T>(T source) where T : class
        {
            DebugCheck.NotNull(source);

            var asObjectQuery = source as ObjectQuery;
            if (asObjectQuery != null)
            {
                return (T)DbHelpers.CreateNoTrackingQuery(asObjectQuery);
            }

            var noTrackingMethod = source.GetType().GetPublicInstanceMethod("AsNoTracking");
            if (noTrackingMethod != null
                && typeof(T).IsAssignableFrom(noTrackingMethod.ReturnType))
            {
                return (T)noTrackingMethod.Invoke(source, null);
            }

            return source;
        }

CreateNoTrackingQuery实现：

public static IQueryable CreateNoTrackingQuery(ObjectQuery query)
        {
            DebugCheck.NotNull(query);

            var asIQueryable = (IQueryable)query;
            var newQuery = (ObjectQuery)asIQueryable.Provider.CreateQuery(asIQueryable.Expression);
            newQuery.ExecutionStrategy = query.ExecutionStrategy;
            newQuery.MergeOption = MergeOption.NoTracking;
            newQuery.Streaming = query.Streaming;
            return newQuery;
        }

取自https://entityframework.codeplex.com

实体框架，AsNoTracking和MergeOption = NoTracking有什么区别？

1 个答案: