我怎么能包括的属性包括沿谓语？ [英] How can I include a predicate along with Included properties?

问题描述

目前我有一个功能，让我查询数据库，同时包括结果其他一些相关的表，以防止打到我知道如果我不这么做，否则发生数据库返回：

 公共类EntityRepository< TEntity> ：IEntityRepository< TEntity>其中，TEntity：类
 {
保护DbSet< TEntity> dbSet; 
 
私人只读的DbContext直流电; 
 
公共EntityRepository（）
 {
直流=新的DbContext（Utility.Config.GetEntityDbConnection（））; 
 dbSet = dc.Set< TEntity>（）; 
} 
 
 
公众的IQueryable< TEntity> GetAllIncluding（PARAMS表达式来; Func键< TEntity，对象>> [] includeProperties）
 {
的foreach（VAR在includeProperties includedProperty）
 {
 dbSet.Include（includedProperty）.Load （）; 
} 
 
返回dbSet; 
} 
} 
  

不过，我需要能够同时使用where子句之前的包括，以便它不会尝试查询整个数据库时，触发加载（）方法。

我试图做这样的事情（这显然是行不通的，因为你可以重新分配 dbset 就像下面我的示例代码）。

 公开的IQueryable< TEntity> SearchForIncluding（表达式来; Func键< TEntity，布尔>>谓语，则params表达式来; Func键< TEntity，对象>> [] includeProperties）
 {
 dbset = dbSet.Where（谓语）; //这不明明WORK 
 
的foreach（在includeProperties VAR includedProperty）
 {
 dbSet.Include（includedProperty）.Load（）; 
} 
} 
  

解决方案

您可以使用 LinqKit 库。下载的NuGet包，并与使用 AsExpandable 扩展方法：

 公开的IQueryable< TEntity> SearchForIncluding（表达式来; Func键< TEntity，布尔>>谓语，则params表达式来; Func键< TEntity，对象>> [] includeProperties）
 {
的IQueryable< TEntity>查询= dbSet; 
 
如果（includeProperties！= NULL）
 {
 =查询includeProperties.Aggregate（查询（目前包括）=> current.Include（含））; 
} 
如果（谓词！= NULL）
 {
 =查询query.AsExpandable（），其中（谓语）。 
} 
返回查询; 
} 
  

Currently I have a function that allows me to query the database while including some other related tables in the results to prevent a return hit to the database that I know would occur otherwise if I don't:

public class EntityRepository<TEntity> : IEntityRepository<TEntity> where TEntity : class
{
    protected DbSet<TEntity> dbSet;

    private readonly DbContext dc;

    public EntityRepository()
    {
        dc = new DbContext(Utility.Config.GetEntityDbConnection());
        dbSet = dc.Set<TEntity>();
    }


    public IQueryable<TEntity> GetAllIncluding(params Expression<Func<TEntity, object>>[] includeProperties)
    {
            foreach (var includedProperty in includeProperties)
            {
                dbSet.Include(includedProperty).Load();
            }

            return dbSet;
    }
}

However, I need to be able to also use a where clause prior to the include so that it doesn't try to query the entire database when it fires the Load() method.

I was trying to do something like this (which obviously doesn't work because you can reassign dbset like in my sample code below).

    public IQueryable<TEntity> SearchForIncluding(Expression<Func<TEntity, bool>> predicate, params Expression<Func<TEntity, object>>[] includeProperties)
    {
           dbset = dbSet.Where(predicate);  //THIS DOESN'T WORK OBVIOUSLY

           foreach (var includedProperty in includeProperties)
           {
                dbSet.Include(includedProperty).Load();
           }
    }

解决方案

You can use the LinqKit library. Download the nuget package and and use the AsExpandable extension method:

public IQueryable<TEntity> SearchForIncluding(Expression<Func<TEntity, bool>> predicate, params Expression<Func<TEntity, object>>[] includeProperties)
{
        IQueryable<TEntity> query = dbSet;

        if (includeProperties != null)
        {
            query = includeProperties.Aggregate(query, (current, include) => current.Include(include));
        }
        if (predicate != null)
        {
            query = query.AsExpandable().Where(predicate);
        }
        return query;
}

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