In the FAQ it says that under the ODMG API, "Objects are registered to
a transaction so that on commit of the transaction it knows" to
properly store modified elements.
I'm having trouble even getting the first stage of this accomplished.
I've modified tutorial 1 to add a discount to the product and I've
added to the Product class a list of product categories to which the
product belongs. This works fine in tutorial 1. I'm able to enter
multiple categories for a product and list them.
The schema for both tutorial 1 and 2 looks like this:
<table name="PRODUCT">
<column name="ID" required="true" primaryKey="true" type="INTEGER"
javaName="_id"/>
<column name="NAME" type="VARCHAR" size="100"/>
<column name="PRICE" type="FLOAT"/>
<column name="DISCOUNT" type="FLOAT"/>
<column name="STOCK" type="INTEGER"/>
</table>
<table name="PRODUCT_CATEGORY_NAME">
<column name="ID" required="true" primaryKey="true" type="INTEGER"
javaName="_id"/>
<column name="NAME" type="VARCHAR" size="100"/>
</table>
<table name="PRODUCT_CATEGORY">
<column name="PRODUCT_ID" required="true" primaryKey="true"
type="INTEGER"/>
<column name="PRODUCT_CATEGORY_NAME_ID" required="true"
primaryKey="true" type="INTEGER"/>
<foreign-key foreignTable="PRODUCT">
<reference local="PRODUCT_ID" foreign="ID"/>
</foreign-key>
<foreign-key foreignTable="PRODUCT_CATEGORY_NAME">
<reference local="PRODUCT_CATEGORY_NAME_ID" foreign="ID"/>
</foreign-key>
</table>
The repository_user.xml file looks like this:
<class-descriptor class="org.apache.ojb.tutorial1.Product"
table="PRODUCT">
<field-descriptor id="1" name="id" column="ID"
jdbc-type="INTEGER" primarykey="true" autoincrement="true"/>
<field-descriptor id="2" name="name" column="NAME"
jdbc-type="VARCHAR"/>
<field-descriptor id="3" name="price" column="PRICE"
jdbc-type="DOUBLE"/>
<field-descriptor id="4" name="discount" column="DISCOUNT"
jdbc-type="DOUBLE"/>
<field-descriptor id="5" name="stock" column="STOCK"
jdbc-type="INTEGER"/>
<collection-descriptor
name="productCategoryNames"
element-class-ref="org.apache.ojb.tutorial1.ProductCategoryName"
auto-retrieve="true"
auto-update="true"
indirection-table="PRODUCT_CATEGORY">
<fk-pointing-to-this-class column="PRODUCT_ID"/>
<fk-pointing-to-element-class
column="PRODUCT_CATEGORY_NAME_ID"/>
</collection-descriptor>
</class-descriptor>
<class-descriptor class="org.apache.ojb.tutorial1.ProductCategoryName"
table="PRODUCT_CATEGORY_NAME">
<field-descriptor id="1" name="id" column="ID"
jdbc-type="INTEGER" primarykey="true" autoincrement="true"/>
<field-descriptor id="2" name="name" column="NAME"
jdbc-type="VARCHAR"/>
<collection-descriptor
name="products"
element-class-ref="org.apache.ojb.tutorial1.Product"
auto-retrieve="true"
auto-update="false"
indirection-table="PRODUCT_CATEGORY">
<fk-pointing-to-this-class column="PRODUCT_CATEGORY_NAME_ID"/>
<fk-pointing-to-element-class column="PRODUCT_ID"/>
</collection-descriptor>
</class-descriptor>
<class-descriptor class="org.apache.ojb.tutorial1.ProductCategory"
table="PRODUCT_CATEGORY">
<field-descriptor id="1" name="id" column="PRODUCT_ID"
jdbc-type="INTEGER" primarykey="true"/>
<field-descriptor id="2" name="id"
column="PRODUCT_CATEGORY_NAME_ID"
jdbc-type="INTEGER" primarykey="true"/>
<reference-descriptor
name="product"
class-ref="org.apache.ojb.tutorial1.Product">
<foreignkey field-id-ref="1"/>
</reference-descriptor>
<reference-descriptor
name="productCategoryName"
class-ref="org.apache.ojb.tutorial1.ProductCategoryName">
<foreignkey field-id-ref="2"/>
</reference-descriptor>
</class-descriptor>
I have gotten this to work in tutorial 1 UCEnterNewProduct.java
apply() by doing this (comments, try/catch, and a few lines removed
for clarity):
Product newProduct = new Product();
String in = readLineWithMessage("enter name:");
newProduct.setName(in);
// ...
// enter and set price, discount, and stock
// ...
in = readLineWithMessage("enter product category:");
while (0 != in.length()) {
ProductCategoryName productCategoryName = new
ProductCategoryName();
productCategoryName.setName(in);
in = readLineWithMessage("enter product category:");
newProduct.addProductCategoryName(productCategoryName);
}
broker.beginTransaction();
broker.store(newProduct);
broker.commitTransaction();
Product looks like this:
public class Product implements java.io.Serializable {
private int id;
protected double discount;
protected double price;
protected int stock;
protected String name;
Vector productCategoryNames = new Vector();
// ...
// all appropriate get/set methods elided
// ...
}
ProductCategoryName looks like this:
public class ProductCategoryName implements java.io.Serializable {
private int id;
protected String name;
Vector products = new Vector();
// ...
// all appropriate get/set methods elided
// ...
}
and ProductCategory looks like this:
public class ProductCategory implements java.io.Serializable {
private int productID;
private int productCategoryNameID;
private Product product;
private ProductCategoryName productCategoryName;
// ...
// all appropriate get/set methods elided
// ...
}
However, I have modified tutorial 2 along the same lines, and have
changed UCEnterNewProduct.java to:
public void apply() {
// get product from user as in tutorial 1
Product newProduct = inputProduct();
Transaction tx = odmg.newTransaction();
tx.begin();
tx.lock(newProduct, Transaction.WRITE);
tx.commit();
}
But this does not seem to work. I read through
odmg/ManyToManyTest.java which has Gourmet objects storing a list of
Food objects, and saw that a Database object was being used to store
the objects.
If I try getting the Database object from the Application and using it
thus:
public void apply() {
// get product from user as in tutorial 1
Product newProduct = inputProduct();
Transaction tx = odmg.newTransaction();
tx.begin();
db.makePersistent(newProduct);
tx.commit();
}
it doesn't work either.
I am running this against MySQL.
Sorry for the newbie question, but can anyone help?
Bill
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