Question

All

My problem is I’m creating a 1-to-many relationship in GORM and expect 2 database tables to be created as backing objects. 3 are created which makes SQL queries overly complex.

I’ve created a close variant on the 1-to-many in the GORM documentation:

class Status {

   List errorMessage

   static hasMany = [errorMessage:ErrorMessage]
}

and the error message class:

class ErrorMessage {

   String message

   static belongsTo = Status
}

I expected this to create two database tables:

CREATE TABLE status {
   ID NUMBER(19,0),
   VERSION NUMBER(19,0),
   //other fields
}

CREATE TABLE error_message {
   ID NUMBER(19,0),
   VERSION NUMBER(19,0),
   STATUS_ID NUMBER(19,0),
   MESSAGE VARCHAR(255)
   //other fields
}

but actually it wants a third table,

CREATE TABLE status_text {
    status_text_id NUMBER(19,0),
    text_idx NUMBER(19,0), 
    text_id NUMBER(19,0)
}

Adding Status to the ErrorMessage (a hack as I don’t want ErrorMessage to have a reference to Status) class removes the third table but keeps the second foreign key resulting in the Text child object having two foreign key fields.

What I want is simple – just a set of objects attached to the parent will be deleted when it is – any thoughts what I’m doing wrong?

Thanks

Answer 1

I don’t think you can satisfy both requirements, i.e. that you have cascading deletes and no join table. You need the belongsTo to get cascading deletes and that makes the relationship bidirectional. To remove the join table, name the belongsTo with the Map syntax:

class ErrorMessage {
   String message
   static belongsTo = [status: Status]
}