如何使LINQ表达式接收参数到通用存储库中的LINQ查询

Question

当我尝试使用iEnumerable系列使用DBSET创建一个加入时，它会引发以下例外，因此我认为我可以包括一个属性，然后通过此属性进行过滤并选择它...

system.invalidoperationException：'linq表达式dbset（） 。加入（ 内部：__p_0， OuterKeySelecter：y =＆gt; y.idtoken， InnerKeySelector：z =＆gt; Z.Idtoken， ResultSelector ：（令牌，Usertokens）=＆gt;代币）'无法翻译。可以通过可以翻译的形式重写查询，或者通过插入“可忽略的”，“ asasyncenumerable”，“ tolist”或“ tolistAsync”来明确切换到客户端评估。请参阅 https://go.microsoft.com/fwlink/？有关更多信息。

   

    public async Task<IEnumerable<TResult>> Join<Tkey, TEntity, VKey, TResult>(IEnumerable<TEntity> collection, Expression<Func<T, Tkey>> outerSelector, Expression<Func<TEntity, Tkey>> innerSelector, Expression<Func<T, TEntity, TResult>> resultSelector)
            where TEntity : class, new()
             where TResult:class,new()
        {
           
                return await Db.Set<T>().Join(collection, outerSelector, innerSelector, resultSelector).ToListAsync();
            
        }

现在，我要使用的查询是这样的，

   public async Task<IEnumerable<TResult>> Join<Tkey,TIncludeProperty, TEntity, TResult>(IEnumerable<T> collection,Expression<Func<T,TIncludeProperty>> includeClause, Func<T, IEnumerable<T>, bool> whereFilter, Expression<Func<T, TResult>> resultSelector)
      where TEntity : class, new()
       where TResult :class,new()
        where TIncludeProperty: class,new()
    {
        try
        {
           
            return await Db.Set<T>().Include(includeClause).Where(x=>whereFilter(x,collection)).Select(resultSelector).ToListAsync();
        }
        catch (Exception ex)
        {
            return Enumerable.Empty<TResult>();
        }
    }

我该如何传递到该方法签名上的集合的位置？

Answer 1

解决方案是修复查询，并使用其中的滤镜过载，以添加另一个滤波器

 public async Task<IEnumerable<TResult>> Join<TIncludeProperty, TEntity, TResult>(IEnumerable<T> collection,Expression<Func<T,TIncludeProperty>> includeClause, Expression<Func<T, TResult>> resultSelector)
      where TEntity : class, new()
       where TResult : class, new()
        where TIncludeProperty: class,new()
    {
        try
        {
            
            return await Db.Set<T>().Include(includeClause).Where(y=> collection.Contains(y)).Select(resultSelector).ToListAsync();
        }
        catch (Exception ex)
        {
            return Enumerable.Empty<TResult>();
        }
    } 

   public async Task<IEnumerable<TResult>> Join<TIncludeProperty, TEntity, TResult>(IEnumerable<T> collection, Expression<Func<T, TIncludeProperty>> includeClause, Expression<Func<T, TResult>> resultSelector, Expression<Func<T, bool>> whereFilter)
      where TEntity : class, new()
       where TResult : class, new()
        where TIncludeProperty : class, new()
    {
        try
        {
            
            return await Db.Set<T>().Include(includeClause).Where(x=> collection.Contains(x)).Where(whereFilter).Select(resultSelector).ToListAsync();
        }
        catch (Exception ex)
        {
            return Enumerable.Empty<TResult>();
        }
    }

Answer 2

嗨，您可以使用此逻辑
,,,,,,

 public virtual IEnumerable<TEntity> Get(Expression<Func<TEntity,bool>>  Where=null)
        {
            IQueryable<TEntity> query = _dbSet;
            if(Where != null)
            {
                query = query.Where(Where);
            }
            return query.ToList();
        }

​
我希望这对你有帮助