ActiveJdbc更新联接表属性

Question

Good evening, I am trying to update a join-table attribute for existing records. I have two models, one called Records , the other called Shoppingcarts . These are connected by a join table called records_shoppingcarts . I added a relationship attribute to the join table called record_amount which is supposed to hold the amount of each record in the join table. At the moment, whenever an item is added to a shoppingcart, only one item is added. The user is then able to modify the amount of items in the shoppingcart in their checkout view. I am handling this by querying the join table records_shoppingcarts for entries with the corresponding record_id and updating the column record_amount to the new amount of records in the shoppingcart. This looks something linke that:

List<RecordsShoppingcarts> associations = RecordsShoppingcarts.where("shoppingcart_id = ?", s.get("id"));

            //update the number of records in the join table
            for(RecordsShoppingcarts rs : associations) {                    

                if((int)rs.getInteger("record_id") == (int)rec.getInteger("id")) {
                    rs.delete(); //cleanup
                    rs.set("record_amount", amount);
                    rs.saveIt();                        

                }
            }                
        }

Unfortunately though, whenever saveIt() gets called; the entry isn't updated in the database but a new entry is created with the same shoppingcart_id , recordId and the updated amount. I am probably missing something here, since I can't imagine manually updating join tables is intended. Unfortunately though, I couldn't find anything on updating relationship attributes in join tables. Is this even provided by ActiveJdbc?

Any help would be much appreciated. Best wishes, derelektrischemoench

Answer 1

The framework is working exactly as expected. You need to familiarize yourself with how it decides to create a new record or update an existing one by reading this page: http://javalite.io/surrogate_primary_keys

Basically, you are deleting a record by:

 rs.delete();

so, next time you do:

rs.saveIt();   

it creates a new record. Simply remove the rs.delete(); and you will be fine.