与GORM建立关系

Question

Hi I don't really understand whay this doesnt work, but im 99% sure its a GORM issue.

here's my domains:

 Class Product{
    String name
    static hasMany = [parts:Parts]
    static mappedBy = [parts:'product']
 }


 Class Parts{
    Product product
    static hasMany = [alternatives:Alternatives] 
 }

so a Product is made up of parts and a part points to a product When I do the following it doesn't save to the database.

 Product p = new Product(name:"test")
 Product part1 = Product.get(2)
 Product part2 = Product.get(3)
 Parts c =  new Parts(product: part1).save(flush:true,failOnError:true)
 Parts c2 =  new Parts(product: part2).save(flush:true,failOnError:true)

 p.addToParts(c)
 p.addToParts(c2)

 p.save(flush:true,failOnError:true)

This doesn't throw any error but also doesn't persist anything to the database.

Any Ideas?

Answer 1

Product p = new Product(name: "test")
Product part1 = Product.get(2)
Product part2 = Product.get(3)

p.addToParts(new Parts(product: part1))
p.addToParts(new Parts(product: part2))
p.save(flush: true, failOnError: true)

The best way to do this is to create the new Parts within your .addToParts() call.

It also seems as though you should have static belongsTo = Product within your Parts class. (Only allowing one side of the Many-to-Many relationship to persist can cause less confusion)