Hello,

I've been staring at COMPONENT and MAP in the hibernate documentation hoping that the answer might come to me. I'm not having any luck and was hoping for some help. :)

The problem can be illustrated with a ONE-TO-MANY relationship between two tables:



I understand that I can create a mapping for OBJECTS which includes a MAP to OBJECT_PROPERTIES (PROPERTY_NAME is the key, PROPERTY_VALUE is the element). Then I can access the key/value pairs from OBJECT_PROPERTIES as a map within OBJECTS.

But, I'd like to take this one step further and actually use the hibernate mapping to define the possible OBJECT_PROPERTIES. This has the benefit of using hibernate's excellent type conversion and custom types.

Therefore, what I want to do seems to me like a combination of MAP and COMPONENT. Except that I want to use the COMPONENT against the values of the map, NOT against physical columns in the database. That is, the COMPONENT would be built up using the key/value pairs in OBJECT_PROPERTIES as opposed to the key/value pairs of a physical database structure.

Any bright ideas on how this might be accomplished?

Thanks for your time,

Ryan

<dynamic-component> ?

Hi, thanks for the suggestion. I took a look at <dynamic-component>. I interpreted its use as:

"Map physical database columns to a hash, where there is a direct correspondence between columns/values of the database and keys/values of the map."

Is this a correct interpretation of <dynamic-component>? If so, this is somewhat the opposite of what I'm trying to do.

What I'm trying to do is: map the key/values built up using two columns of a table (OBJECT_PROPERTIES in the example above) to the actual methods of an object. For example, if the table OBJECT_PROPERTIES had the following rows:



I want to map the row with the PROPERTY_NAME of "FIRST_NAME" to a method on OBJECT 1234 named getFirstName(), for example.

I understand the normal solution would be to simply add a column called FIRST_NAME to the OBJECTS table. :) But, OBJECTS will contain many different subclasses of OBJECT, all with very different OBJECT_PROPERTIES. Being able to map the name/value pairs from OBJECT_PROPERTIES to the different OBJECT subclasses is what we're trying to accomplish.

Any ideas?

Thanks again,

Ryan

To summarize, I guess what I need is a <component> that loads and persists its values like a <map>. A <map> can build its key/value pairs from the rows of a table, whereas a <component> can only formulate its key/value pairs from the physical structure of a database. A component would be perfect except for its reliance on the physical structure of the database.

Is there a way to write a custom component type that loads and persists values more like a <map>? I'm trying to combine the database flexibility of a <map>, with the typing/mapping functionality of a <component>.

Thanks,

Ryan