linq - EntityFramework Core Union Select - Null Related Data -

to better picture, trying have feed composed different elements (i'll try make example short possible) :

public class feeddto     {         public int type { get; set; }         public datetime date { get; set; }          [jsonproperty(nullvaluehandling = nullvaluehandling.ignore)]         public commentdto comment { get; set; }          [jsonproperty(nullvaluehandling = nullvaluehandling.ignore)]         public likedto { get; set; }          public static feeddto setcomment(comment comment, int userid)         {             return new feeddto             {                 type = activity_feed_type.comment,                 date = comment.createdate,                 comment = comment.adapt(userid)             };         }          public static feeddto setlike(like like, int userid)         {             return new feeddto             {                 type = activity_feed_type.like,                 date = like.createdate,                 = like.adapt(userid)             };         }     } 

and here try query data :

public iqueryable<feeddto> feed(int userid)         {              var listcomments =                 context.comments                     /* includes ... */                     .select(x => feeddto.setcomment(x, userid));              var listlikes =                 context.likes                     /* includes ... */                     .select(x => feeddto.setlike(x, userid));              return listlikes.union(listcomments).orderbydescending(x => x.date);  } 

---

the issue :

• when return each 1 alone, without union works
• when try union related data in feeddto methods null