比较两个列表并根据 Linq C# 中的 Id 从第一个列表返回数据

Question

var solutionItems = solutionInfoResponse
  .Items
  .Where(x => solutionInfoResponse
     .ProductGroup
     .FirstOrDefault(p => productGroupIds.Contains(p.GroupId))
     .Items
     .Any(it => it.Id == x.ItemId))
  .ToList();

Here I am getting List of FirstProduct group only with exist in ProductGroupsIds , so I want all product group with existing same condition. Please Help me.

Here

 public class ProductGroup
    {
        public string GroupId { get; set; }
        public List<ProductGroupItem> Items { get; set; }

    }

and

  public class ProductGroupItem
    {
        public string Id { get; set; }
        public string Description { get; set; }
       
    }

and

public class SolutionItem
{
    public string ItemId { get; set; }

}

Finally

   public class SolutionInfoResponse
    {
        public List<SolutionItem> Items { get; set; }
        public SolutionInfo SolutionInfo { get; set; }
        public List<ProductGroup> ProductGroup { get; set; }
    }

Answer 1

If it's possible that the same item can be in several groups we should not use FirstOrDefault but Where . We obtain all such groups and then check if there's any groupItem with required Id :

var solutionItems = solutionInfoResponse
  .Items
  .Where(item => solutionInfoResponse
     .Groups
     .Where(group => productGroupIds.Contains(group.GroupId))
     .SelectMany(group => group.Items)
     .Any(groupItem => groupItem.Id == item.Id))
  .ToList();