Many-to-many association, Spring and Hibernate

[spring04]

I've two classes Project and Resource which has many-to-many association. I've introduced an association class ProjectResource and made this many-to-many into 2 one-to-many associations.

In Spring, each method provided in DAO is inside a transaction. ProjectDao class has an insertProject and when i want to insert object Project, i'll call this method. In my JUnit tests, after i insert project, i also want to insert Resource object. Resource Class has a composite id (projectId and resourceId and other attributes as in any association class). Class My question is, DO I NEED TO HAVE A DAO (ProjectResourceDao) for the association class ProjectResource?


If i had to implement this in Hibernate without Spring, as i control the transaction, this is what i'll do.

Begin Transaction
Create Project object
Insert Project object
Create Resource Object
Insert Resource object

Create ProjectResourceObject
// NO Insert ProjectResource as the constructor will automatically take care of it.
End transaction


As they all are running in the same txn, hibernate will detect the association (bidirectional navigation?? ) and insert an entry in the ProjectResource table).


In spring, in my Facade interface, i added a method "insertProjectAndResource" which takes the argument project, resource and projectResource. (i added this as i want this all to happen in one transaction). In this, i do the following:

1. insertProject
2. insertResource
3. create an object projectResource

As projectResource object already has references to projectId and resourceId (composite Id), i would expect Hibernate to insert a corresponding entry for this. But i couldn't see this happening.


Could some one tell me what's that i'm missing and what i'm doing is correct or NOT? If not correct, how else should i do it?

Thanks!

Here's how my ProjectResource constructor looks:

[/code][code]
/**
* @param username
* @param startDate
* @param endDate
*/
public ProjectResource( String username, Date startDate, Date assignmentDate, Project proj, Resource res) {
this.username = username;
this.startDate = startDate;
// this.endDate = endDate;
this.assignmentDate = assignmentDate;

this.project = proj;
this.resource = res;

// Set key values

this.id.projectId = project.getId();
this.id.resourceId = resource.getId();

// Guarantees referential integrity
project.getProjectResources().add(this);
resource.getProjectResources().add(this);
}

Class Project {
.......
Set projectResources;
.....
}


Class Resource {
.....
Set projectResources;
.....
}

[spring04]

Could someone please provide answer for my question?

Thanks!