How to create meta - tags in .hbm.xml files

Smudo99 · **Joined:** Thu Mar 30, 2006 4:53 am **Posts:** 12

Hibernate version:3.1
Hibernate Tools version:3.1.0 beta5
Name and version of the database:Oracle 10g

Hi,

i want to set the default-value meta tag via reveng, so i think i need to set the defaultValue in the Column Object.
Is there an easy way to do that, or how can i program a workaround?

Michael

vinaykumar · **Posted:** Tue Apr 25, 2006 9:58 am

Smudo99 · **Joined:** Thu Mar 30, 2006 4:53 am **Posts:** 12

I don't understand, but I think this won't solve my problem.

My DB has defined a lot of default values.

Like

Code:

...
DUMMY VARCHAR2(20) DEFAULT 'Hello World' NOT NULL
...

Now i want to create Mapping-Files with these default

Code:

<hibernate-mapping>
  ...
    <property name="dummy" type="string">
      <meta attribute="default-value">Hello World</meta>
      <column name="DUMMY " length="20" not-null="true" />
    </property>
  ...
</hibernate-mapping>

And after that i want to create the POJO

Code:

private String dummy = "Hello World";

Thanx for help

Michael

Smudo99 · **Joined:** Thu Mar 30, 2006 4:53 am **Posts:** 12

Ok, i have created the META tag. I modified the JDBCMetaDataDialect, the JDBCReader and the columns.ftl.

So my JDBC Configuration includes the COLUMN-DEF, but how do i get it into the generated POJO, some ideas?

I tried one day to create the correct POJO, but no chance so long.

Thanx for ideas,

Michael

max · **Posted:** Thu Apr 27, 2006 4:48 am

you would need to call out $pojo.getMetaString("default-value")

Smudo99 · **Joined:** Thu Mar 30, 2006 4:53 am **Posts:** 12

$pojo.getMetaString("default-value") throws an exception - Methode does not exist. I tried $pojo.getMetaAsString("default-value", ""), but on the way from JDBCReader to the BasicPOJOClass the "default-value" value got lost.

The only MetaAttribute i still have in my POJOs ist "use-in-equals".

Michael

max · **Posted:** Thu Apr 27, 2006 5:41 am

well you said you modified jdbcreader ? does it add the tag correctly ?

Smudo99 · **Joined:** Thu Mar 30, 2006 4:53 am **Posts:** 12

In JDBCReader.processBasicColumns() the column.setDefaultValue() is set. I get the COLUMN_DEF in the JDBCMetaDataDialect.getColumns().

I don't found anything where it is set to the POJOClass object, that is used by the $pojo.getMetaAsString() method.

max · **Posted:** Thu Apr 27, 2006 7:17 am

so you are setting it on the coluymn, then akso read it from the column.

Smudo99 · **Joined:** Thu Mar 30, 2006 4:53 am **Posts:** 12

I changed the JDBCBinder, so that the PersistenceClass which is created include the MetaAttribute "default-value". Now it works fine!

I thought this is the better way, instead of using the column. Or what do you mean.

Thx Michael

P.S.: Is it planned, that this feature is included into the reveng tool? (i don't mean my dirty hack!!)

max · **Posted:** Thu Apr 27, 2006 10:07 am

well, i don't really see the benefit of including default column in the pojo's. default column in the mapping files maybe; but only as an option.

patches welcome.

romatenen · **Joined:** Tue Nov 15, 2005 12:25 pm **Posts:** 15

I also interested in generation of default values.
Can you send me changes you made to get defaults working

max · **Posted:** Mon May 01, 2006 12:19 pm

guys could you please explain to me why defaults are cool to generate into the pojo's ?

Things I have against them:

1) they can change in the db
2) one property not always equal to one column

sorin7486 · **Joined:** Thu Aug 03, 2006 3:43 am **Posts:** 45

well you are right max... but it's still a nice feature to have if you need it and can't go around it... (other than doing it by hand)

I am using hivernate tools 3.2.0-beta9a, and I modified it so that it adds the meta tags just like Smudo99 said ... more or less... I updated the template to the latest revision of the repository (I was using a custom template and it didn't add the tags to the hbm files). I also changed the default RevengStrategy class to include a method that would tell me if a certain type is to use default values from the database(if available).

There is only one small thing left to do: for example in the case of Date fields the default value is 'Now' so inside the pojo I get Date name = 'Now'; instead of Date name = new Date(); ... Is there any way to do this other than modifying the getFieldInitialization method ?

max · **Posted:** Mon Feb 19, 2007 3:09 am

getFieldInitialization() is the right place for this.

You still did not answer my questions on why it is cool to initialize the values to default when that default value will not be the correct one. e.g. Now is a good example of a value that it will be wrong to initialize with since it won't be 'Now' in db sense, but 'Now' for the time it was instantiated.