I am working on hbm2java. I would like to implement association management for bidi mappings, and submit my work for inclusion in the tool if it is of interest. I need some help to find the name of the property at the opposite end of the association, details below.

Hibernate version:3.2.2, tools: 3.2.0 beta 9

Mapping documents:

From Car.hbm.xml:
<set name="wheels" inverse="true">
<key column="CAR_ID" />
<one-to-many class="Wheel" />
</set>

From Wheel.hbm.xml:
<many-to-one name="car" class="Car" column="CAR_ID" not-null="true" foreign-key="CAR_FK"/>

Desired output:

public void addWheel(Wheel wheel) {
if(wheel == null){
throw new IllegalArgumentException("Cannot add a null " + Wheel.class.getName());
}
if(wheel.getCar() != null){
wheel.getCar().removeWheel(wheel);
}
wheel.setCar(this);
getWheels().add(wheel);
}

public void removeWheel(Wheel wheel) {
getWheels().remove(wheel);
}

Achieved so far: (new template: PojoAssociationManagers.ftl added to Pojo.ftl)

<#if pojo.needsAssociationManagers()>
<#foreach property in pojo.getAllPropertiesIterator()>
<#if pojo.getMetaAttribAsBool(property, "gen-property", true)><#if c2h.isOneToMany(property)>
<#assign parameterName = pojo.getSingularNameFor(property)
parameterType = c2h.getOneToManyReferencedEntityType(property)
capitalizedParameterName = pojo.beanCapitalize(parameterName)
propertyName = pojo.getPropertyName(property)>
public void add${capitalizedParameterName}(${parameterType} ${parameterName}) {
if(${parameterName} == null){
throw new IllegalArgumentException("Cannot add a null " + ${parameterType}.class.getName());
}
if(${parameterName}.get{---Parent---}() != null){
${parameterName}.get{---Parent---}().remove${capitalizedParameterName}(${parameterName});
}
${parameterName}.set{---Parent---}(this);
get${propertyName}().add(${parameterName});
}

public void remove${capitalizedParameterName}(${parameterType} ${parameterName}) {
get${propertyName}().remove(${parameterName});
}
</#if></#if></#foreach></#if>

Output:

public void addWheel(org.example.domain.Wheel wheel) {
if(wheel == null){
throw new IllegalArgumentException("Cannot add a null " + org.example.domain.Wheel.class.getName());
}
if(wheel.get{---Parent---}() != null){
wheel.get{---Parent---}().removeWheel(wheel);
}
wheel.set{---Parent---}(this);
getWheels().add(wheel);
}

public void removeWheel(org.example.domain.Wheel wheel) {
getWheels().remove(wheel);
}

Outstanding:

I need to do two things:
1. Find the name of the property used in the "many" end of the association to reference the "one" end. In the output above, the placeholder ---Parent--- should be "Car". Note, of course, that the type of the entity owning the many end of the relationship is not the correct name here, we need the name of the property used by the entity at the "many" end.

2. (Less important) I would like to use the unqualified class name for the entity on the many side (i.e. Wheel rather than org.example.domain.Wheel)

If someone could help with these I would be most grateful :)

Cheers,

Russell

Added methods:
I have added the following methods to enable the templating above:

org.hibernate.tool.hbm2x.pojo.BasicPOJOClass:

public String getSingularNameFor(Property property){
String str = property.getName();
return ReverseEngineeringStrategyUtil.simpleSingularize(str);
}


org.hibernate.cfg.reveng.ReverseEngineeringStrategyUtil:
public static String simpleSingularize(String plural) {
String[][] suffixMap = {{"ies", "y"},{"uses", "us"},{"ses", "se"},{"x", "x"},{"s", ""}};
for(int i = 0; i < suffixMap.length; i++){
String suffix = suffixMap[i][0];
String replacement = suffixMap[i][1];
if(plural.endsWith(suffix)){
plural = plural.substring(0, (plural.length() - suffix.length()));
plural += replacement;
break;
}
}
return plural;
}

org.hibernate.tool.hbm2x.Cfg2HbmTool:

(Probably a bad name...)
public String getOneToManyReferencedEntityType(Property property){
if(!isOneToMany(property)){
throw new IllegalArgumentException(property.getName() + " is not one-to-many");
}
OneToMany oneToMany = null;
Value value = property.getValue();
if(value instanceof Collection) {
oneToMany = (OneToMany)((Collection)value).getElement();
} else {
oneToMany = (OneToMany)value;
}
return getClassName(oneToMany);
}

Sounds great you want to look into this.

You can see EntityPOJOClass.getOneToMappedBy which does *some* of this.

Note, make the generation of this logic dependent on a flag, e.g. "genbidirectional".

http://opensource.atlassian.com/project ... owse/HBX-5 is the relevant jira for this.

When you start contributing it then please do it via patches to the above jira.

thanks.

In the spirit of sharing, here's my association management freemarker template (PojoPropertyAccessors.ftl). It is a bit specific to my implementation, but it might lend a few tricks.



For unidirectional associations, it generates:



And for bidirectional:

I am trying to generate Associations (OneToMany) using hbm2java.
Does the thread and above ftl file means that by default hbm2java doesn't support Associations.

Can u give me a working copy of the PojoPropertyAccessors.ftl with Associations. I have tried to use the copy above and the following ant tasks and it doesn't work

<hbm2java jdk5="true" ejb3="true"/>
<hbmtemplate
templatepath="${basedir}/templates/pojo/PojoPropertyAccessors.ftl"
templateprefix="pojo/"
template="pojo/PojoPropertyAccessors.ftl"
filepattern="{package-name}/{class-name}.java">
<property key="jdk5" value="true" />
<property key="ejb3" value="true" />
</hbmtemplate>

As I stated, the ftl I posted is highly specific to my architecture and is in no way applicable out-of-the-box. For instance, I strip of the 'For' and 'By' on multi-homed associations, which requires tinkering with other templates.

hbm2java does form the associations correctly, but does not generate collection management routines in the POJOs. As evidenced by rushealy's post, it may be on the horizon.

hi anansi,

it seems you are using the property names to find a "best match"; that might work sometimes - but definitly not all the time (but as you already said its highly dependent on your way of doing things - which is fine ;)

I just like to point out that the correct way of finding the "other side" is to find the opposite property that uses the same columns as the key/column.

Absolutely Max, hence my plethora of caveats. ;)