Hi Jeremy,
An ideal method would allow the database to enforce the constraint,
either via true multi-column uniqueness (then you can use
ConstrainedBean.unique("col1", "col2")) or some other type of db
constraint. I don't know much about db stuff, so I'll defer here.
Maybe you could redesign away the problem. Perhaps a base class,
MyBean, then two extensions: MyBeanActive & MyBeanInactive. Both
classes have a non-persisted "active" property. MyBeanActive has the
constraint of uniqueness on name, while MyBeanInactive does not. The
MetaData classes could set the "active" field appropriately using the
afterRestore() callback. Or, you could just set it in a veneer or
helper class you use for retrieving and saving the records. You'd be
managing two different tables in this case.
Another way, though non-ideal, is to use the beforeValidate() method of
the CallbacksProvider interface. This is workable, but non-ideal since
it is possible for two simultaneous validations to pass the validation
before they write a record, then write the record at roughly the same
time, resulting in two database entries. It additionally feels
non-ideal to me because now the MetaData class is 'heavy' -- it depends
on ContentQueryManager now instead of the validation framework.
An example for doing that follows:
====================================
public class MyBeanMetaData extends MetaData implements CallbacksProvider {
...
public Callbacks getCallbacks() {
return new AbstractCallbacks<MyBean>() {
public boolean beforeValidate(MyBean item) {
try {
ContentQueryManager<MyBean> mbMgr = new
ContentQueryManager<MyBean>(getDatsource(), MyBean.class);
MyBean existingRecord =
mbMgr.restoreFirst(mbMgr.getRestoreQuery().where("name", "=",
item.getName()). where("active","=","Y"));
if( existingRecord != null ) {
// Note: How do we indicate the
source of the problem back to the
user?
return false;
}
return true;
} catch (Exception e ) {
return false;
}
}
}
}
protected Datasource getDatasource() {
Config config = Config.getRepInstance();
Datasource mDatasource =
Datasources.getRepInstance().getDatasource(Config.getRepInstance().getString("MYBEAN_DATASOURCE",
Config.getRepInstance().getString("DATASOURCE")));
return mDatasource;
}
}
====================================
Josh
--
Joshua Hansen
Up Bear Enterprises
(541) 760-7685
Jeremy Whitlock wrote:
> Hi All,
> Right now I'm using the GenericQueryManager and a class extending
> MetaData to validate new beans for insertion into a database. What I
> would like to do is have this validation work on multiple columns and
> from what I can tell right now, it is not. Let's talk about an
> example first then I will post code.
>
> Lets say I have a row in the database like this:
>
> NAME ACTIVE
> --------- ------------
> Testing Y
>
> If I created a bean with a NAME="Testing" and an ACTIVE="Y", I would
> expect the GQM to say the bean is invalid for insertion into the
> database. This works right now. Now, if I had a row like this:
>
> NAME ACTIVE
> --------- ------------
> Testing N
>
> and I created a bean with NAME="Testing" and an ACTIVE="Y", I want the
> GQM to say that the bean is valid for insertion to the database. Now
> that we know what I want, let me show you some related code:
>
> MetaData
> -------------
> addConstraint(new ConstrainedProperty("id")
> .identifier(true)
> .editable(false)
> .unique(true)
> );
>
> addConstraint(new ConstrainedProperty("active")
> .notEmpty(true)
> .notNull(true)
> .maxLength(1)
> .regexp("(Y|N){1}")
> .unique(true)
> );
>
> addConstraint(new ConstrainedProperty("name")
> .notEmpty(true)
> .notNull(true)
> .maxLength(64)
> .regexp("([\\s\\-A-Za-z0-9]*)")
> .unique(true)
> );
>
> Here is the code I'm using for the validation, although it shouldn't matter:
>
> SomeElement
> -------------------
> ((Validated)bean).validate(MyAppUtils.getGenericQueryManager(MyClass.class))
>
> What do I need to do to my MetaData class to allow for multiple-column
> unicity checks, if it is even available? If it is not available, how
> would you suggest working around this? Basically, I've got a table
> that holds objects in it that can be active or inactive. If an object
> is active, you shouldn't be able to create a new object in that table
> with the same name. If an object is inactive, you should be able to
> create a new object with the same name as the inactive object.
>
> Thanks in advance,
>
> Jeremy
>
> >
>
>
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