Re: [Chicken-users] rails-like framework

[Thomas Chust]

On Sat, 22 Apr 2006, PeterBex wrote:

> [...]
> I think the hardest thing will be the ActiveRecord-like support since
> Scheme isn't especially object-oriented.  The question is whether
> that is really required.  The most important aspect about Rails is that
> it has decent defaults.  You can just build a database and run Rake
> to set up a Rails environment and you have a bare-bones interface to
> the database out of the box.  To do things, you need the very minimum
> of custom code.  This is the essence of what makes Rails so popular.
> I'm not sure if this can be done as easily in a non-object-oriented
> environment.  Ruby makes it easy to automatically build objects from
> information because it allows you to add members to existing classes.
> I think with the Prometheus egg we could do something like this.
> [...]

Hello,

I don't know exactly what you would expect from a runtime object <-> 
database row interface, but I can't imagine that it requires a lot of 
effort to create something simple that gets the job done -- no matter 
which object system is used.

A small example using TinyCLOS and SQLite3 is attached. It does runtime 
generation of classes and accessor methods completely automatically from 
the database schema and is terribly easy to use because I didn't have the 
time to make up something sophisticated. The code allows you to write 
something like this:

    ;;; load extensions
    (require-extension
      sqlite3 tinyclos sqlite3-tinyclos)

    ;;; create a database
    (define db
      (sqlite3:open "test.db"))

    (sqlite3:exec db #<<EOD
      CREATE TABLE eggs(name TEXT NOT NULL,
                        license TEXT, is_module INTEGER NOT NULL DEFAULT 0,
                        PRIMARY KEY(name), CHECK(is_module IN (0, 1)));
EOD
)

    ;;; define the object class
    (sqlite3:define-stored-object-class db "eggs")

    ;;; add some data
    (let ((egg (make <egg> "sqlite3")))
      ;; now the entry should already exist
      (print (sqlite3:in-store? egg))
      ;; let's add some data
      (set-license! egg "BSD")
      ;; and read it back
      (print (license egg))
      ;; other fields are filled with default data
      (print (module? egg))
      ;; changing the primary key is possible as well
      (sqlite3:set-pk! egg "foo")
      (print (sqlite3:pk egg))
      ;; which does not change data, of course
      (print (license egg))
      ;; and we can also delete the entry
      (print (sqlite3:remove-from-store! egg))
      ;; then it is gone
      (print (sqlite3:in-store? egg)))

    ;; close database connection
    (sqlite3:finalize! db)

cu,
Thomas

sqlite3-tinyclos.scm
Description: Mini bridge between SQLite3 and TinyCLOS