实体框架核心联接并包含内部实体

Question

List<Item> Item = (from it in _context.Item
join iv in _context.ItemVersions on it.Id equals iv.ItemId
join iot in _context.ItemOriginalTitles on iv.Id equals iot.ItemVersionId                    
where term.ToLower() == "all" || (it.Name.ToLower() == term.ToLower() || it.Name.ToLower().Contains(term.ToLower()) || iot.Value.Contains(term) || 
queryable.Any(x => iot.Value.Contains(x.SearchText)))
select new Item
{
Id = it.Id,
Name = it.Name,
TypeCodeId = it.TypeCodeId,
TypeCode = it.TypeCode,
OriginalLangId = it.OriginalLangId,
SubGenreCodeId = it.SubGenreCodeId,
ItemVersions = it.ItemVersions
}
).Include("ItemVersions.OriginalTitles").ToList();

正如您所看到的，我正在尝试将OriginalTitles添加到ItemVersions实体中，但无法做到这一点(OriginalTitles始终是null(。商品型号：

public class Item
{
[Key]
public int Id { get; set; }
public string Name { get; set; }
public int TypeCodeId { get; set; }
public TypeCodes TypeCode { get; set; }
public int? OriginalLangId { get; set; }
public int SubGenreCodeId { get; set; }
public List<ItemVersion> ItemVersions { get; set; }      
}

和我的ItemVersions模型：

public class ItemVersion
{
[Key]
public int Id { get; set; }
public string Name { get; set; }
public List<ItemOriginalTitle> OriginalTitles { get; set; }
public List<ItemShortTitle> ShortTitles { get; set; }
public List<ItemSynopsis> ItemSynopsis { get; set; }
public List<ItemLongSynopsis> ItemLongSynopsis { get; set; }
public List<ItemLanguage> ItemLanguages { get; set; }
public List<VersionChannel> VersionChannels { get; set; }
public bool IsDefault { get; set; }
public Item Item { get; set; }
public int ItemId { get; set; }
}

如果可能的话，寻找一种立即包含它的方法，而无需对其进行迭代。感谢

Answer 1

Try(将Include方法移动到join子句，在该子句中选择表(:

List<Item> Item = from it in _context.Item
join iv in _context.ItemVersions.Include("OriginalTitles") on it.Id equals iv.ItemId
join iot in _context.ItemOriginalTitles on iv.Id equals iot.ItemVersionId                    
where term.ToLower() == "all" || (it.Name.ToLower() == term.ToLower() || it.Name.ToLower().Contains(term.ToLower()) || iot.Value.Contains(term) || 
queryable.Any(x => iot.Value.Contains(x.SearchText)))
select new Item
{
Id = it.Id,
Name = it.Name,
TypeCodeId = it.TypeCodeId,
TypeCode = it.TypeCode,
OriginalLangId = it.OriginalLangId,
SubGenreCodeId = it.SubGenreCodeId,
ItemVersions = it.ItemVersions
};

Answer 2

因为我初始化了一个新对象，所以包含内部实体并不重要。我的解决方案是返回db对象并将includes移到其中：

Item = (from it in _context.Item.Include("ItemVersions.OriginalTitles")
join iv in _context.ItemVersions on it.Id equals iv.ItemId
join iot in _context.ItemOriginalTitles on iv.Id equals iot.ItemVersionId
where term.ToLower() == "all" || (it.Name.ToLower() == term.ToLower() || it.Name.ToLower().Contains(term.ToLower()) || iot.Value.Contains(term) ||
queryable.Any(x => iot.Value.Contains(x.SearchText)))
select it          
).ToList();