findByExample including superclass

icoserve · **Joined:** Thu May 04, 2006 4:04 am **Posts:** 5

hi!

i have a few tables in my database with fields which represent the same properties(for example id,lastModifiedBy and statusDeleted).in my java classes i want the following class hierarchy

DB looks like:
table1:
id,
lastModifiedBy

table2:
id
lastModifiedBy
statusDeleted

table3:
id
lastModifiedBy

table4
id
lastModifiedBy

and so on...

and my java classes look like

abstract class entity
private id
getters/setters

class modified extends entity
private lastModifiedBy
getters/setters

class deletable extends modified
private statusDeleted
getters/setters

class table2 extends deletable
priavte otherFields
getters/setters

class table4 extends modified
private otherFields
getters/setters

i changed nothing in the mapping files, because hibernate is able to set all the properties, because it finds the setters for all properties.
my problem is that, when i make a search by example and only set the id for my example(table4.setId=123), hibernate don't regard that the property id is set and searches for the whole table volume with where(1=1).
is there a way to tell hibernate, that the class table4 has a superclass(or two) which properties also are necessary??

if you don't clearly understand my problem, please contact me or answer my post that i can describe my problem in an other way for more understanding.
THANKS!

Hibernate version:
3.0
Name and version of the database you are using:
Oracle 9i

tenwit · **Joined:** Thu Dec 23, 2004 9:08 pm **Posts:** 2008

Query by example ignores IDs. Have a look in the ref docs, section 15.6, "Example Queries". After all, if you have to ID, you'd use session.get(), not criteria.

Use normal criteria or HQL for this.

icoserve · **Joined:** Thu May 04, 2006 4:04 am **Posts:** 5

but when i try the following:

Code:

Table4 example = new Table4();
example.setLastModifiedBy("someone");
List<Table4> result = session.createCriteria(Table4.class).add(Example.create(example)                                .ignoreCase().list();

hibernate doesn't check that the field lastModifiesBy of the superclass has changed and should be regarded in the generated select statement. (iwant a statement like: select id,... from Table4 where lastModifiedBy=? and not select id,... from Table4 where(1=1))
so is there no way to tell hibernate that there are also superclasses of my object which include fields for my select statement?
if this is the case, then I only can use HQL for this!?

thanks for replies!!

tenwit · **Joined:** Thu Dec 23, 2004 9:08 pm **Posts:** 2008

As far as I know, non-ID properties of mapped superclasses are used in example queries. How have you mapped the relationship between Table1 and Table4? Are you using hibernate's polymorphic mapping features (<subclass>, <union-subclass> or <joined-subclass>)? Hibernate doesn't care that one class extends another: the class' mapping must extend the other class' mapping for hibernate to consider it.

icoserve · **Joined:** Thu May 04, 2006 4:04 am **Posts:** 5

there is no relationship between table1 and table4, maybe i expressed my problem not exactly enough.

table4 in db
+id
+lastModifiedBy
+field1
+field2
+field3

hibernate has generated a mapping like:
<class name"Table4" table=table4" schema="someSchema">
<id name="id" type=long">
<column name="id" precision="12" scale="0" />
<generator class="assigned" />
</id>

<property name="lastModifiedBy" type="String">
<column name="lastModifiedBy" length="20" />
</property>

<property name="field1String" type="String">
<column name="field1" length="20" />
</property>

<property name="field2String" type="String">
<column name="field2" length="20" />
</property>

<property name="field3String" type="String">
<column name="field3" length="20" />
</property>

my java classes:

Code:

public class Entity{
   protected long id;

   public long getId(){
      return id;
   }

   public void setId(long id){
      this.id=id;
   }
}

public class Modifiable extends Entity{
   protected String lastModifiedBy;

   public String getLastModifiedBy(){
      return this.lastModifiedBy;
   }

   public void setLastModifiedBy(String lastModifiedBy){
      this.lastModifiedBy=lastModifiedBy;
   }
}

public class Table4 extends Modifiable {

   private String field1String;
   private String field2String;
   private String field3String;

   public String getField1String() {
      return field1String;
   }

   public void setField1String(String field1String) {
      this.field1String = field1String;
   }

   public String getField2String() {
      return field2String;
   }

   public void setField2String(String field2String) {
      this.field2String = field2String;
   }

   public String getField3String() {
      return field3String;
   }

   public void setField3String(String field3String) {
      this.field3String = field3String;
   }
}

i hope that it is now more clearly. where do i have to tell(and how) hibernate the subclass mapping, so that i can make an example search. like i have described before:

Quote:

Table4 example = new Table4();
example.setLastModifiedBy("someone");
List<Table4> result = session.createCriteria(Table4.class).add(Example.create(example) .ignoreCase().list();

tenwit · **Joined:** Thu Dec 23, 2004 9:08 pm **Posts:** 2008

lastModifiedBy is in the mapping for Table4, so it should be checked in the example query. It doesn't matter that the method is in a java superclass, what's important is that it's in the mapping (or the mapping's super-mapping, if it's a polymorphic mapping, which it's not in this case). I think that the query you wrote should work (assuming that there's a second close-paranthesis after the ignoreCase()).

Can you get any property to be checked in the example query? If you call setField2String("string"), does the query work? I suggest tweaking your code to narrow down the cause of the problem, because it looks all good to me.