Depeche

What is Depeche?

Depeche is a database mapper. What do I mean by that? It enables you to work with databases using data structures. Queries are Lists of records, and records are Maps of field names to field values. It strives to be very easy to use and prevent mistakes.

Here are some of the features:

• No checked exceptions (I think they are a plague).
• Dynamic query building using simple methods; also, queries can be passed around and used to create other queries.
• Also welcome to use raw SQL.
• Lazy evaluation - don't run queries unless/until you need to.
• Result caching - after running a query once, it stores the results so it doesn't need to run again. If you want to run it again, just clear the results or use a new query.
• No problem with multiple-column primary keys and foreign keys.
• Simple transaction support
• No configuration required, but supports configuration through "properties files" and JNDI
• Currently supports PostgreSQL, MySQL, MS SQL Server and FileMaker; support for other databases can be added easily.

Requirements

Currently, Depeche requires Java 6 and SLF4J.

Is this an ORM?

Depeche is not an ORM because it doesn't go all the way to objects (beans). However it could be used as part of an ORM. Also, the way it works can help with certain tasks, such as displaying the result of a query or generating a form.

With an ORM, you would normally go from the database through some kind of data structures, to objects, and then use reflection to iterate over objects and their properties as if working with data structures. With Depeche, the "objects" part is eliminated and you can work directly with the data structures.

Why yet another database library for java?

Because I haven't found one that I really like. Besides, I thought it would be fun to implement my own library.

Why call it "Depeche"?

Several reasons: "dépêche" means "hurry" in French, and this library can hopefully help develop applications quickly; Depeche is inspired from Django, so I thought it would be nice to keep the musical theme, and Depeche Mode is one of my favorite bands.

Enough with the talk, let's see some code!

Provider p = new PGProvider("localhost", "sample", "user", "pass");
for (Record rec : p.query("person").filter("first_name", "John").order("last_name")) {
	System.out.println(rec);
}

{id=4, first_name=John, last_name=Brown, sex=M}
{id=2, first_name=John, last_name=Smith, sex=M}