= Python scripting framework =

See the section on Python in the [SoftwarePrereqsUnix Software Prerequisites].

== Structure ==

The directory `boinc/py/Boinc` contains the `Boinc` module. This means if you have `boinc/py/` in your python path you can write for example:
{{{
from Boinc.setup_project import *
}}}
To ensure `boinc/py/` is in your python path:
{{{
import boinc_path_config
}}}
This is a special module that `configure` places in relevant directories which then modifies `sys.path` appropriately.

== Project-specific settings ==

The module `boinc_project_path` is imported to get the paths for `config.xml` and `run_state.xml`. The default paths for these are the parent directory of the invocation script. You can override these defaults
 1. modify this file directly (if you have only one project on your server or have separate copies for each)
 1. create a new boinc_project_path.py and place it earlier in PYTHONPATH than the default one
 1. define environment variables

Example `boinc_project_path.py`
{{{
  config_xml_filename = '/etc/boinc/yetiathome/config.xml'
  run_state_xml_filename = '/var/lib/boinc/yetiathome/run_state.xml'
}}}
See the source of file `boinc/py/Boinc/boinc_project_path.py` for details.

== Directories containing python scripts ==

||boinc/py/Boinc/*.py||Main BOINC python modules||
||[StartTool boinc/sched/start]||BOINC start / Super Cron program||
||[XaddTool boinc/tools/xadd]||Adds objects to the database||
||[MakeProject boinc/tools/make_project]||Creates a project||
||boinc/test/test*.py[[BR]]cgiserver.py||Test scripts: see the [//test.php testing framework].||

== Python modules in '''boinc/py/Boinc/''' ==

||`boinc_path_config.py.in`||`Configure` puts `boinc_path_config.py` in all directories that need it; see above||
||`boinc_project_path.py`||sets where `config.xml` et al can be found; see above.||
||`configxml.py`||reads and writes `config.xml` and `run_state.xml` - see its pydoc for more information||
||`boinc_db.py`||auto-generated file that contains database constant definitions, e.g. `RESULT_OUTCOME_SUCCESS = 1`||
||`setup_project.py`||internal module for creating a project. See [MakeProject make_project] and test scripts.||
||`database.py`||defines database backend functions and database operations; see below.||
||`db_mid.py`||'middle-end': optional mix-in to ease debugging by allowing printing of database objects directly||
||`util.py`||miscellaneous functions||
||`version.py.in`||version and platform-specific definitions snarfed by `configure`||

== Python database access ==
`Database.py` defines database backend library and database table and object relationships to allow easy data manipulation.

All [DataBase database tables] have a corresponding class and its rows have classes, where each column is a member of that class. Ids are automatically translated to and from objects. To begin, import the `database` module:

{{{
from Boinc import database
}}}
Connect to the database:
{{{
database.connect_default_config()
}}}
Table classes can be indexed using the [ ] operator to retrieve an object by id; e.g.
{{{
# executes 'select * from project where id=1'.
# exception is raised if project is not found
project_with_id_1 = database.Projects[1]
}}}
Table classes have a `find` function that builds and executes a MySQL query based on its arguments:
{{{
# this could return any number (0, 1, 2, ...) of platforms
# executes "select * from platform where user_friendly_name='commodore 64'"
list_of_platforms_called_c64 = database.Platforms.find(
    user_friendly_name = 'Commodore 64')
}}}
Find can take any number of arguments; they are ANDed. For more advanced usage such as custom SQL queries (anything is possible) see the pydoc.
{{{
all_apps = database.Apps.find()
finished_yeti_wus = database.Workunits.find(
    app = database.Apps.find(name='YETI@home')[0],
    assimilate_state = ASSIMILATE_DONE)
}}}
Objects (table rows) have their column data as members so you can access and modify them directly.
{{{
user_quarl = database.users.find(email_addr='quarl@quarl.org')[0]
print 'name =', user_quarl.name
user_quarl.postal_code = 97404
}}}
To create a new database object, create a Python object and give all values as parameters to the initializer:
{{{
new_app = database.App(name='SPAGHETTI@home',
                       min_version=1,
                       create_time=time.time())
}}}
To commit any changes (including a new object), call `commit()` (the tool `boinc/tools/add.py` is a command-line interface to this):
{{{
user_quarl.commit()  # executes an UPDATE
new_app.commit()     # executes an INSERT
}}}
To remove an object, call `remove()`:
{{{
team_eric_test = database.Teams(name="Eric's Test Team")[0]
team_eric_test.remove()
#                        OR
for team in database.Teams(name="Eric's Test Team"):
    team.remove()
#                        OR
map(database.Team.remove,database.Teams(name="Eric's Test Team"))
}}}
To access objects related by id, access the field name without "id" suffix: (the `result` table has columns '`workunitid`' and '`hostid`'; the `host` table has column `userid`)
{{{
wu_1234 = database.Workunits.find(name='1234.wu')[0]
results_of_wu_1234 = database.Results.find(workunit=wu_1234)
for result in results_of_wu_1234:
    os.system("echo 'you are crunching %s' | mail '%s'" %(
               result.name, result.host.user.email_addr))
}}}

||'''Table'''||'''Python table object'''||'''Python row object class'''||
||project||Projects||Project||
||platform||Platforms||Platform||
||app||Apps||App||
||app_version||!AppVersions||!AppVersion||
||user||Users||User||
||team||Teams||Team||
||host||Hosts||Host||
||workunit||Workunits||Workunit||
||result||Results||Result||