Is it possible to simply define primary key composed from more than 1 field using xdoclet and if, how. Any example please.

I can't find good examples of using hibernate+xdoclet.

Thanks

Johnny

Here is an approach that works, but it's not exactly the nicest solution. The biggest problem is that the id class is required to implement Serializable as well as the equals and hashCode methods.

I suppose it would be possible to enhance XDoclet to generate the code for the internal id class. At any rate, here ya go...


public class BankAccount {
private Id _id;
private String _name;

public static class Id implements Serializable {
private String _bankAccountNumber;
private String _bankAbaNumber;
public Id() {
}
/**
* @hibernate.property column="BANK_ACCT_NUM"
*/
public String getBankAccountNumber() { ... }
/**
* @hibernate.property column="BANK_ABA_NUM"
*/
public String getBankAbaNumber() { ... }
//.... setters, and must implement equals and hashCode
}

public BankAccount() {
}
/**
* @hibernate.id class="BankAccount$Id" generator-class="assigned"
*/
public Id getId() { return _id; }
/**
* @hibernate.property column="NAME"
*/
public String getName() { return _name}

//....
}

I would like to define primary key compounded from more than one filed using xdoclet simply without using special id class.
This should result to generation of xml like this:

<?xml version="1.0"?>

<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 2.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd">

<hibernate-mapping>
<class
name="com.exit.test.hibernate.beans.AssetClass"
table="ASSET_CLASS_TBL"
dynamic-update="false"
dynamic-insert="false"
>

<composite-id>
<key-property name="assetClassID"/>
<key-property name="name"/>
</composite-id>

<property
name="assetClassID"
column="assetClassID"
type="java.lang.Integer"
/>

<property
name="name"
type="java.lang.String"
update="true"
insert="true"
column="name"
/>

<property
name="description"
type="java.lang.String"
update="true"
insert="true"
column="description"
length="200"
/>

......etc........

If your using XDoclet have you not decided on a topdown development approach thus you will implement the ID class anyway. So adding the tags there for the mapping document is correct is it not? I dont think I understand your development method. You want to generate (partially) the POJOs?

Ok, I am new to hibernate. So there is no way to have POJO object, that have composit primary key without special id-class?

I am generating POJO objects with XDoclet tags from old system from java files with some attributes in comments (similar to POJO with XDoclet, but different, proprietary solution).

So I must generate id-classes where composite primary key is used?
I think it is not very good solution. Because primary key is not component. It is only subset of columns in entity, table, POJO...
I would like simply mark with XDoclet tag, that this column is part of primary key, this column is also part of primary key, and this is simply property of entity, POJO.....

I'm not positive, but I think Hibernate requires you to have "PK" classes for compound primary keys (at least that is always the way I have used it when I can't get away from the evils of compound keys).

One thing that might help you though to expand on my example is that you can provide "helper" methods on the domain objects like so:



At least this approach makes the internal id classes transparent to most application code. You can also provide helpers on the setter methods if you want.

It's a bit of a pain, but then again so are a lot of things when dealing with tables with compound primary keys.

[quote="loverde"]I'm not positive, but I think Hibernate requires you to have "PK" classes for compound primary keys (at least that is always the way I have used it when I can't get away from the evils of compound keys).[/quote]


This is not correct. Hibernate does not require that. It is totaly legal to say something like:


<composite-id>
<key-property name="n1" column="col1" />
<key-property name="n2" column="col2" />
<key-property name="n3" column="col3" />
</composite-id>

as long as your persistent class is Serializable and has equals and hasCode ()
methods this will work.

The problem is with XDoclet it just has no capabilities to generate the above (at least the latest one from sf.net) by say looking at @hibernate.key-property or something like that.

Alex.[/code]

It is true that you can have external PK class (recommended approach) or use an integrated version. As far as I know XDoclet does not currently support integrated compound Keys.

So what is conclusion?

1. I must use id-class if I want to use XDoclet+compositePrimaryKeys?

2. Or there is possible to use some merging to achieve:
<composite-id>
<key-property name="n1" column="col1" />
<key-property name="n2" column="col2" />
</composite-id>

Hi boys, there is open improvement in XDoclet forum, this is exactly answer to my question:

http://opensource.atlassian.com/projects/xdoclet/secure/ViewIssue.jspa?key=XDT-414&watch=true


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Thanks

I can only tell you what I did.

Open up the xdt that generates your mapping and insert an extra insertion point for the kind of composite-id that you need. Then you will only need those composite ids described in a file that will be merged.

Inserting the merge point is not brainer just grep for the phrase that is being generated currently in your mapping file, that says you need to create some sort of file to be able to provide additional info for this mapping. Note, that the problem with this insertion point is that it comes a bit too late, to insert composite-id so you will need your own.

It is a bit ugly, but works fine for me.

HTH,
Alex.

Can you help me more how to do it with merging, any example, link?

The solution should be sumitted to XDoclet JIRA for consideration for inclusion. That way the community will benefit.