联接或可变DBContext存储库通用c# [英] Join or Mutible DBContext Repository Generic c#

问题描述

我有通用的存储库，可以在其中执行Get，Update，Insert的方法.

I have repository generic where I do method as Get,Update,Insert.

我使用这种方法从数据库中的表中获取数据.

I get a data from table in data base I use this method.

 public IEnumerable<typeEntity> Get<typeEntity>(Expression<Func<typeEntity, bool>> newObjectEntity,int page, int rowsByPage) where typeEntity : class
    {
       List<typeEntity> Result = null;
            Result = Context.Set<typeEntity>().Where(newObjectEntity).OrderBy(m => true).Skip<typeEntity>(5 * (page - 1)).Take<typeEntity>(rowsByPage).ToList<typeEntity>();
        return Result;
    }

我仅在一张表中获取数据时，这是我的代码:

I when get data only a one table this is my code:

var collecProducts = repository.Get<Products>(c => true);

我的问题是什么时候我想买两台平板电脑，我该怎么办?我找到了这段代码，但是非常慢.

My problem is when I want get two tablet How I do this?. I find this code but is very slow.

var collecProducts = repository.Get<Products>(c => true);
var collecCategory = repository.Get<Category>(c => true);

var collectProductToCategory = (from p in collecProducts
                                           join c in collecCategory on p.idCategory equals c.idCategory).ToList();

此代码的问题是获取所有产品和类别的数据，我只想从SQL Server中获取例如加入TSQL所需的数据.

The problem this code is that get all data de products and category and I want from SQL Server only data necessary for example as join TSQL.

select p.idProducts from products p join category c on p.idCategory = c.idCategory

总而言之，自存储库泛型以来，如何使用联接获取数据.

In conclusion How I could get data use join since repository generyc.

推荐答案

您找到的解决方案很慢，因为存储库方法正在立即实现/执行查询，而不是允许延迟执行.尝试从存储库方法中的查询中删除".ToList()":

The solution you found is slow because the repository method is materializing/executing the query immediately instead of allowing deferred execution to occur. Try removing the ".ToList()" from the query within the repository method:

public IEnumerable<typeEntity> Get<typeEntity>(Expression<Func<typeEntity, bool>> newObjectEntity,int page, int rowsByPage) where typeEntity : class
{
   IEnumerable<typeEntity> Result = null;
        Result = Context.Set<typeEntity>().Where(newObjectEntity).OrderBy(m => true).Skip<typeEntity>(5 * (page - 1)).Take<typeEntity>(rowsByPage);
    return Result;
}

这将使您能够构成和构造更高阶的查询，而无需立即将整个表拉入内存.

This will allow you to compose and construct higher order queries without pulling the whole table into memory immediately.

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