Re: mapping collections of PC Object types

Craig Russell Mon, 01 Aug 2005 17:29:09 -0700

Hi Michelle,

On Aug 1, 2005, at 3:32 PM, Michelle Caisse wrote:

Hi Craig,

Could you take a look at my proposed mapppings and schema below? I have a few specific questions at the relevant places below.

0. Use a join table, and use foreign keys for the elements to refer to the primary table

1. Use a join table, and embed the elements column by column

2. Use a join table, and serialize the elements

3. Serialize the entire ArrayList.

Currently we have, taking ArrayListCollections as an example:
public static final String [] fieldSpecs = {
"public ArrayList ArrayListOfObject0",
"embedded-element=true public ArrayList ArrayListOfObject1",
"embedded-element=false public ArrayList ArrayListOfObject2",
...
}

We want:
public static final String [] fieldSpecs = {
"public ArrayList ArrayListOfObject0", [ArrayList in join table, elements in join tables]
"embedded-element=true public ArrayList ArrayListOfObject1", [ArrayList in join table, elements embedded]
"embedded-element=false <element serialized=true> public ArrayList ArrayListOfObject2", [ArrayList in join table, elements serialized]
"serialized=true public ArrayList ArrayListOfObject3", [ArrayList serialized in columns of primary table]

** QUESTION: I'm not sure how much to attempt to test defaults (unspecified values for embedded-element, serialized.

You have the default case in ArrayListOfObject0. It defaults to serialized=false, embedded-element=false, using a join table.

What you don't have is the explicit serialized=false, embedded-element=false. I don't know that it's important.

______
orm:

<orm>
   <package name="org.apache.jdo.tck.pc.fieldtypes">
   <class name="ArrayListCollections" table="ARRAYLIST_COLLECTIONS">
   <field name="identifier" column="IDENTIFIER" primary-key="true"/>
   <field name="ArrayListOfObject0"
table="ARRAYLIST_OF_OBJECT0">
   <join column="IDENTIFIER"/>
   <element column="OBJREF">
<foreign-key/>
   </element>
   <order column="INDEX"/>
   </field>
   <field name="ArrayListOfObject1"
table="ARRAYLIST_OF_OBJECT1">
<element>
<embedded>
<field="intval" column="INTVAL"/>
<field="stringval" column="STRINGVAL"/>
   </embedded>
</element>
<order column="INDEX"/>
   </field>
   <field name="ArrayListOfObject2"
table="ARRAYLIST_OF_OBJECT2">
   <join column="IDENTIFIER"/>
   <element column="OBJVAL" serialized="true"/>
   <order column="INDEX"/>
   </field>

Yes, because serialized=true is not (ever) the default for a field.

<field name="ArrayListOfObject3"
column="ARRAYLIST_OF_OBJECT3" serialized="true">
   </field>
...
______
jdo:

<jdo>
<package name="org.apache.jdo.tck.pc.fieldtypes">
<class name="ArrayListCollections" identity-type="application"
   objectid-class="org.apache.jdo.tck.pc.fieldtypes.ArrayListCollections$Oid">
<field name="identifier" primary-key="true"/>
<field name="ArrayListOfObject0" >
<collection element-type="java.lang.Object">
</collection>
</field>
<field name="ArrayListOfObject1" >
<collection element-type="java.lang.Object" embedded-element="true">
</collection>
</field>
<field name="ArrayListOfObject2" >

It's n/a. The mapping is embedded serialized so this doesn't matter.

Craig

<collection element-type="java.lang.Object" embedded-element="false">
</collection>
</field>
<field name="ArrayListOfObject3" >
<collection element-type="java.lang.Object">
</collection>
</field>
...
______
Schema:

CREATE TABLE ARRAYLIST_COLLECTIONS
(
   IDENTIFIER INTEGER NOT NULL,
   ARRAYLIST_OF_OBJECT3 LONG VARCHAR FOR BIT DATA,
   ARRAYLIST_OF_SIMPLE_CLASS3 LONG VARCHAR FOR BIT DATA,
   ARRAYLIST_OF_SIMPLE_INTERFACE3 LONG VARCHAR FOR BIT DATA,
   ...
);

-- element neither serialized nor embedded
CREATE TABLE ARRAYLIST_OF_OBJECT-
(
   IDENTIFIER INTEGER REFERENCES ARRAYLIST_COLLECTIONS NOT NULL,
   OBJREF BIGINT REFERENCES SIMPLE_CLASS NOT NULL,
   INDEX INTEGER NOT NULL
);

-- embedded-element="true"
CREATE TABLE ARRAYLIST_OF_OBJECT1
(
   IDENTIFIER INTEGER REFERENCES ARRAYLIST_COLLECTIONS NOT NULL,
   INTVAL INTEGER NOT NULL,
   STRINGVAL VARCHAR(128) NOT NULL,
   INDEX INTEGER NOT NULL
);

-- <element serialized="true">
CREATE TABLE ARRAYLIST_OF_OBJECT2
(
   IDENTIFIER INTEGER REFERENCES ARRAYLIST_COLLECTIONS NOT NULL,
   OBJVAL LONG VARCHAR FOR BIT DATA,
   INDEX INTEGER NOT NULL
);

Thanks!

-- Michelle

Craig Russell

Architect, Sun Java Enterprise System http://java.sun.com/products/jdo

408 276-5638 mailto:[EMAIL PROTECTED]

P.S. A good JDO? O, Gasp!

smime.p7s
Description: S/MIME cryptographic signature

Re: mapping collections of PC Object types

Reply via email to