Does Roo support n:m mappings ?

[pbernet]

I'm quite fond of the features Roo M2 provides. While looking at the samples I did not find a sample of a n:m mapping - How would that work in Roo ?

Regards.
Paul

[Stefan Schmidt]

Hi Paul,

Roo currently offers two commands to generate JPA relationships:

add field reference

which generates a @ManyToOne JPA relationship mapping, and

add field set

which generates a @OneToMany JPA relationship.

Take a look at the clinic.roo script to see how to use them.

So to get a n:m relationship you would typically create three tables:

Order
-OneToMany->OrderOrderLine

OrderOrderLine
-orders @ManyToOne->Order
-orderlines @ManyToOne->OrderLine

OrderLine
-OneToMany->OrderOrderLine

Hope this helps.

-Stefan

[joshuapurcell]

Great thread thanks alot... I've been stumbling on when to use 'add field set' and 'add field reference' ever since I began using Roo. Now if I can only figure out the most straightforward way of making a 1:1 relationship by using Roo I'll be all set.

[Stefan Schmidt]

Hi Paul,

Basically you are already using the right command for this . Just use the 'add field reference' command to essentially create a one-to-one mapping as seen in the clinic.roo script.

On the MVC side this will create a dop-down list where you can choose only one element as opposed to the 'add field set' which creates a multi-selection box on the MVC side.

Hope this helps.

-Stefan

[pbussche]

Hi Stefan,

would you mind pasting the roo commands for this n:m mapping, I am struggeling to get this done here. Basically I want to have a community which has a number of persons in it and a person who can be member of different communities. But I am not sure how to write this in roo.

Thanks,
Philipp

[Stefan Schmidt]

@pbussche,

Below the script for a true n:m mapping:

project --topLevelPackage com.foo.opensource
persistence setup --provider HIBERNATE --database HYPERSONIC_IN_MEMORY
entity --name ~.domain.Community --testAutomatically
field string name
entity --name ~.domain.Person --testAutomatically
field string name
field set --fieldName communities --element ~.domain.Community --cardinality MANY_TO_MANY 
field set --element ~.domain.Person --fieldName members --class ~.domain.Community --cardinality MANY_TO_MANY 
controller all --package ~.web

I hope this helps .

Cheers,
Stefan

[pbussche]

Cool, thanks. That works.
But it seems now that I have to store on the community side which person is part of it and on the person side which community he is a member of. Well I overwrote one setter method to automatically do that when a person is created and a community is specified but is that the recommended way of doing it ?
I guess this is more persistence basics than roo, sorry

[bozzo@celi.it]

@Stefan
...
I'm trying ROO. Tutorial studying and so on.
Your example is exactly what I need now, but... it doesn't work for me!
I mean:
- i create three person: A, B and C;
- i create two communities: X and Y;
- i associate A and B to X and C to Y;
- from the communities list, I can't see the association done.

It looks like data isn't consistent. Can you help me please??

[Stefan Schmidt]

Can you share your script so we can see what exactly you are seeing in your application?

[bozzo@celi.it]

Thanks for your reply Stefan!

// Spring Roo 1.0.0.RELEASE [rev 564] log opened at 2010-01-12 22:15:57
project --topLevelPackage it.celi
persistence setup --provider HIBERNATE --database HYPERSONIC_PERSISTENT
database properties list
database properties set --key database.url --value jdbc:hsqldb:${user.home}/dd4-cloe-roo
database properties list
entity --class ~.domain.BusinessFunction
field string code --notNull --sizeMin 1 --sizeMax 30
field string specialRequests --sizeMax 100
test integration
controller scaffold ~.web.BusinessFunctionController
selenium test --controller ~.web.BusinessFunctionController
perform test
// script --file /home/fabio/wedding.roo
quit
// Spring Roo 1.0.0.RELEASE [rev 564] log closed at 2010-01-12 22:17:36
// Spring Roo 1.0.0.RELEASE [rev 564] log opened at 2010-01-12 22:24:42
entity --class ~.domain.UserRole
field string --fieldName id --notNull --sizeMin 1 --sizeMax 30
field string --fieldName description --sizeMax 100
field set --fieldName allowedFunctions --element ~.domain.BusinessFunction 
quit
// Spring Roo 1.0.0.RELEASE [rev 564] log closed at 2010-01-12 22:34:43
// Spring Roo 1.0.0.RELEASE [rev 564] log opened at 2010-01-12 22:36:51
controller scaffold --entity ~.domain.UserRole --class ~.web.UserRoleController
selenium test --controller ~.web.UserRoleController
quit
// Spring Roo 1.0.0.RELEASE [rev 564] log closed at 2010-01-12 22:39:37
// Spring Roo 1.0.0.RELEASE [rev 564] log opened at 2010-01-12 22:45:51
perform eclipse
quit
// Spring Roo 1.0.0.RELEASE [rev 564] log closed at 2010-01-12 22:59:29

Ok with BusinessFunction now.
Then... I create a UserRole. I update a field, like description. I list all roles and....... roo duplicates it. I find the 'old' with his relations with BusinessFunctions and the new one.
I can't understand.