java - Hibernate @OneToMany tries to insert null -

i have following simple example. when runs, see quoterequest object being generated auto-generated id. next, see accidents object being generated, quote_request_id that's being inserted null, error:

column 'quote_request_id' cannot null

@entity @table(name = "quotes") public class quoterequest {     public quoterequest(){}      @id     @column(name = "quote_request_id")     @generatedvalue(strategy = generationtype.identity)     private long quoterequestid;       @onetomany(mappedby = "quoterequest", cascade = cascadetype.all)     @ordercolumn(name = "accidents_id")     private accidents[] accidents;      // getters , setters }  @entity @table(name = "accidents") public class accidents {     public accidents()     {     }      @id     @generatedvalue(strategy = generationtype.identity)     @column(name = "accidents_id")     private long accidentid;       @column(name = "amount", nullable = false)     private float amount;      @manytoone(optional = false, cascade = cascadetype.all)     @joincolumn(name = "quote_request_id", nullable = false)     private quoterequest quoterequest;      // getters , setters } 

why isn't inserting newly generated id accidents column?

when creating accidents, don't set quoterequest property. should doing that? need have bi-directional relationship?

this reason.

first, "do need have bi-directional relationship?". well, 1 can tell. however, having bi-directional relationship. way set up, accident side owning relationship. means, db column accident.quote_req_id relying on field accident.quoterequest. have not populate field, hibernate assuming null. hence inserting null. expected behavior.

in short, should make sure quoterequest.accident , accident.quoterequest consistent, example:

class quoterequest {     private list<accident> accidents;  // prefer list or set      public void setaccidents(list<accident> accidents) {         this.accidents = new arraylist<>(accidents);         (accident accident:accidents) {             accident.setquoterequest(this);         }     } }  class accident {     private quoterequest quoterequest;     public setquoterequest(quoterequest quoterequest) {         // there more...         this.quoterequest = quoterequest;     } } 

this basic example on like. in short, need accident.quoterequest set appropriate value. there still lots of issue in above implementation , leave (e.g. when has accidents set , replaced list)