saving/loading generic java type to postgresql database column

Question

I'm trying to implement some simple auditing functionality for my java app. Here's a snippet of my audit class:

public class Audit<C, T> {
    public final Class<C> modifiedClass;
    public final Date modificationTime;
    public final MyFieldMeta<C, T> fieldMeta; //contains Class<T>
    public final T newValue;

    //constructor, etc...
}

When it comes to persisting these audit objects, I'd prefer to have just one table storing all varieties independent of what T is. I'm using postresql, and I'm wondering what the best approach is for saving newValue to a column, then getting it back again.

newValue is limited to fairly simple types that have postgresql equivalents - String, Integer, Date etc. So storing the value as text and the type as varchar in a separate column, then mapping them back in the java wouldn't be too hard. Is there a slicker approach?

Alan Escreet · Accepted Answer · 2011-05-10 07:09:57Z

1

Once you 'flatten' the data types in your database, you will rely on logic to convert it back, which could cause problems. Consider the value: 11.12

Is that text 11.12, as in chapter numbers? Is that 11.12 as in a monetary value? Is that 11th December?

Unless you can guarantee that a value can always be distinctly mapped to a type, the only other way around it is to add an additional type marker to the field, which you must then parse out, for instance: s11.12 to mean "a String of value 11.12".

answered May 10, 2011 at 7:09

Alan Escreet

3,5692 gold badges25 silver badges19 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Paul Bellora Over a year ago

as I said, I could store both the type and value, so inferring the type is not an issue. I guess my question is a) is there a more elegant way than the option I mentioned? and b) does this approach/architecture make sense in general for simple auditing functionality?

Alan Escreet Over a year ago

This method is simple, if not very elegant. A little nicer and more flexible would be to have a separate column for the type. For a simple audit, it should be fine. Just be aware of the limitations regarding adding support for new data types in later. If the data types won't change (much), then you shouldn't have problems with maintenance.

Collectives™ on Stack Overflow

saving/loading generic java type to postgresql database column

1 Answer 1

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related