one to many - Hibernate insert cascade not inserting foreign key -

i have 2 entities:

@entity public class file ....... @id @generatedvalue(strategy=generationtype.auto) private int id; @onetomany(fetch=fetchtype.lazy, mappedby="file", cascade=cascadetype.all) private list<tag> tags; ....... other properties .......  @entity public class tag ....... @id @generatedvalue(strategy=generationtype.auto) private int id; @manytoone @joincolumn(name="file_id") private file file; @column private string tag; ....... other properties ....... 

i trying insert file (and subsequently tag) doing following:

file file = new file(); tag tag = new tag(); tag.settag("tag1"); tag2 tag2 = new tag(); tag2.settag("tag2"); list<tag> tags = new arraylist<tag>(); tags.add(tag); tags.add(tag2); file.settags(tags); ---add other file attributes here--- 

i inserting file in dao using:

sessionfactory.getcurrentsession().saveorupdate(file);  

in logs see insert "file" table , 2 inserts tag table, however, foreign key in tag table points file table (file_id) null.

what possibly doing wrong?

you not setting file tag, tag's file. remember in oop, opposed relational model, have set both ends of relationship. can't navigate tag file because added set of tags file. in case, can navigate file tag (ie: list tags file). can't tell file tag belongs to, looking @ tag.

what done helper method in 1 of models, this:

public void addtag(tag tag) {   this.tags.add(tag);   tag.setfile(this); } 

see this example (from hibernate's test suite):