Grails 数据绑定

Question

I need to bind request parameters to an instance of the following Java class (getters and setters omitted):

public class ShippingHouse {

    private String name;
    private String description;
    private List<ShippingRule> shippingRules = new ArrayList<ShippingRule>();  
}

public class ShippingRule {

    private ShippingHouse shippingHouse;
    private String name
}

Notice that there is a 1:N relationship between ShippingHouse and ShippingRule , but each ShippingRule also has a reference to the ShippingHouse thaat owns it.

If these were Grails command/domain classes, I would bind them with request parameters

name=foo&description=bar&shippingRules[0].name=sr0&shippingRules[1].name=sr1

But it doesn't seem like this will set the reference to the owning ShippingHouse within each ShippingRule . Is there a way I can bind this automatically, or must I write the code myself?

Answer 1

Don,

You will need to write code to do it yourself using BindUsing or some other approach. The binder doesn't (and shouldn't) assume anything about back references from a parent to a child. If these were GORM entities and the relationship was explicit, that is different, but in your case the binder should not assume that shippingHouse property in the ShippingRule class has anything to do with the shippingRules property in the ShippingHouse class.

Also note that lucke84 said that your "private" is implicit. Make sure you understand what that means if you are going to remove them. If you remove them the compiler is going to generate public getter and setter methods for those properties, which may or may not be what you want.

Answer 2

If you want to implement a 1:N relationship between the two classes, you should use the right grails approach. Something like this:

class ShippingHouse {
    String name
    String description
    static hasMany = [shippingRules: ShippingRule]
}

class ShippingRule {
    String name
    static belongsTo = [shippingHouse: ShippingHouse]
}

Please note that semicolons are useless and the "private" declaration on class fields is implicit.