[bug]不包含“AsNoTracking”的定义

摘要

在使用ef做查询优化的时候我们会用到AsNoTracking方法，但如果不引入命名空间，你就会出现不包含“AsNoTracking”的定义的错误。

解决办法

引入命名空间：System.Data.Entity

AsNoTracking是对IQueryable的扩展，看它的定义就可以知道，代码片段如下：

  //

        // 摘要:

        //     Returns a new query where the entities returned will not be cached in the

        //     System.Data.Entity.DbContext or System.Data.Entity.Core.Objects.ObjectContext.

        //     This method works by calling the AsNoTracking method of the underlying query

        //     object. If the underlying query object does not have an AsNoTracking method,

        //     then calling this method will have no affect.

        //

        // 参数:

        //   source:

        //     The source query.

        //

        // 类型参数:

        //   T:

        //     The element type.

        //

        // 返回结果:

        //     A new query with NoTracking applied, or the source query if NoTracking is

        //     not supported.

        public static IQueryable<T> AsNoTracking<T>(this IQueryable<T> source) where T : class;

  //

        // 摘要:

        //     Returns a new query where the entities returned will not be cached in the

        //     System.Data.Entity.DbContext or System.Data.Entity.Core.Objects.ObjectContext.

        //     This method works by calling the AsNoTracking method of the underlying query

        //     object. If the underlying query object does not have an AsNoTracking method,

        //     then calling this method will have no affect.

        //

        // 参数:

        //   source:

        //     The source query.

        //

        // 返回结果:

        //     A new query with NoTracking applied, or the source query if NoTracking is

        //     not supported.

        public static IQueryable AsNoTracking(this IQueryable source);