Paster

Finely hand-crafted python code is great but:

• I hate typing it in
• I make a lot of tpyos

Paste Script command rdfSubject allows RDFAlchemy model files to be generated from your schema file.

Commands From Paster

The RDFAlchemy group is currently local (could be global).

1. Install PasteScript. If you don't have it:

   easy_install PasteScript
   

2. Ensure you have a dev version of RDFAlchemy above > rev 132. If you are updateing from a previous install, be sure to re-run the install as in:

   # from the rdfalhemy dir
   python setup.py develop
   

3. From that dir you should now be able to "see" the paster commands.

   #> paster
   Usage: /usr/local/bin/paster COMMAND
   usage: paster [paster_options] COMMAND [command_options]
   
   options:
     --version         show program's version number and exit
     --plugin=PLUGINS  Add a plugin to the list of commands (plugins are Egg
                       specs; will also require() the Egg)
     -h, --help        Show this help message
   
   Commands:
     create       Create the file layout for a Python distribution
     help         Display help
     make-config  Install a package and create a fresh config file/directory
     points       Show information about entry points
     serve        Serve the described application
     setup-app    Setup an application, given a config file
   
   rdfalchemy:
     rdfSubject   Create an rdfSubject subclass with descriptors from an RDF Schema
   

Those last lines mean that the rdfalchemy group is available to you. From that location you can:

1. Type paster rdfSubject -s ./rdfalchemy/samples/schema/foaf.rdf...select an option (select 10 for foaf:Person)

2. Type paster rdfSubject --help for ... well you know.

3. Type paster rdfSubject -s /home/me/project/schemas/MyEsotericSchema.rdf to see the rdfSubject(s) you can create a .py for.

What you Get

The output is almost certainly not suitable for use without modification. Consider it a skel to save you some typing. Some considerations:

1. Determining the correct descriptor is not possible from just the schema. rdfMultiple is the default. If you pull up the initial output in an editor and do a search/replace from rdfMultiple -> rdfSingle and then say yes or no, you can quickly get the descriptors you want.

2. You can change the descriptor name to anything you want

     py_attr_name = rdfMultiple(MYNS["schema-attr-name"])`
   

3. There are probably more Namespace variables than you need. Delete away if you wish.

4. You will probably find that the command produces more than you need or want. It's easier to delete lines than to type them :-)

Some sample output for foaf:Person:

from rdfalchemy import rdfSubject, Namespace, URIRef
from rdfalchemy.rdfsSubject import rdfsSubject
from rdfalchemy.orm import mapper

XML = Namespace("http://www.w3.org/XML/1998/namespace")
OWL = Namespace("http://www.w3.org/2002/07/owl#")
RDFS = Namespace("http://www.w3.org/2000/01/rdf-schema#")
DOAP = Namespace("http://usefulinc.com/ns/doap#")
VS = Namespace("http://www.w3.org/2003/06/sw-vocab-status/ns#")
DC = Namespace("http://purl.org/dc/elements/1.1/")
RDF = Namespace("http://www.w3.org/1999/02/22-rdf-syntax-ns#")
FOAF = Namespace("http://xmlns.com/foaf/0.1/")

class Project(rdfsSubject):
        """Proyecto A project."""
        rdf_type = DOAP["Project"]
        programming_language = rdfMultiple(DOAP["programming-language"])
        tester = rdfMultiple(DOAP["tester"])
        homepage = rdfMultiple(DOAP["homepage"])
        old_homepage = rdfMultiple(DOAP["old-homepage"])
        repository = rdfMultiple(DOAP["repository"], range_type = DOAP["Repository"])
        documenter = rdfMultiple(DOAP["documenter"])
        download_mirror = rdfMultiple(DOAP["download-mirror"])
        category = rdfMultiple(DOAP["category"])
        download_page = rdfMultiple(DOAP["download-page"])
        os = rdfMultiple(DOAP["os"])
        bug_database = rdfMultiple(DOAP["bug-database"])
        maintainer = rdfMultiple(DOAP["maintainer"])
        mailing_list = rdfMultiple(DOAP["mailing-list"])
        translator = rdfMultiple(DOAP["translator"])
        screenshots = rdfMultiple(DOAP["screenshots"])
        release = rdfMultiple(DOAP["release"], range_type = DOAP["Version"])
        wiki = rdfMultiple(DOAP["wiki"])
        developer = rdfMultiple(DOAP["developer"])
        helper = rdfMultiple(DOAP["helper"])
mapper()

Commands from other locations

To make expose the rdfalchemy paster commands from within you project or framework, in the egg dir for you project (pylons, turbogears etc)

• add rdfalchemy
• to Project_Name.egg-info/paster_plugins.txt

Future

Code generation is a difficult and neve-rending hole that I shalll not cast myself to deeply into. Feedback is good but rdfSubject is a command to assist in your project development. It won't do it for you.