Hi

I have a situation where the system administrator can add extra columns to a table whenever necessary. A set of “meta data” tables are used to define what the columns represent.

For example the administrator may define an extra column for the client table called “firstContact”. He would then add information to the “meta data” tables stating that the “firstContact” column on the client table represents the ID code of the user who made the first contact with the client, and can be linked to the table that defines the user.

I was thinking of representing these extra fields as a collection of “custom field” objects owned by my Client object. Each custom field object would map to a column in the table (instead of the normal row in a table), The actual mapping would be determined at run time by reading the meta data, and then creating a mapping data (via the classes in net.sf.hibernate.mapping)

Is this the right approach?

Is there a simpler way of doing this?

Or am I expecting too much from hibernate?



(Technically I believe that loading a set of components from a single row is called a “pivot” table.)

You can also look at dynamic-component and dynamic-class (this one in H3 only) - Not very well documented, but useful

Forgetting for the moment that this has to be done at run time :)

I have a table “Client” with the following columns



I which to map to the following class


Where Fields will contain a list of all the custom fields. So I have an interface
and I create a class for each type of custom field.

My mapping looks like



It would have been nice if the design had used a simple one to many table, but instead a pivot table was used!

I have the exact same problem, did you find a solution for this?

I followed the man's advice and used hibernate V3 which supports dynamic classes and components.

I then wrote some code to turn the map that hibernate produces into an array of usefull field classes.

Beware, use habernate V3 beta, not V3rc1 as dynamic mapping in 3rc1 is currently not working (a known issue).

Thanks, I'll give that a go.

Hi,

Sorry for bothering again. But I am still not really sure what to do.

Here is my mapping file :


The map that is produces contains values for id and field1, but our application can insert another column into the table, that is not reflected in the map until we add it to the mapping file.

Is there any way to specify that it should load all column values into the map?

Thanks.[/code]

Not that I know of. We run some SQL to get the metadata of the tables and their foreign keys and then generate a hibernate mapping DOM. This DOM is then added to the hiberante configuration object and a new SessionFactor is then built.