SahanaPy Framework

We have built an S3 framework as a higher level of abstraction on top of T2.
This should be used by modules where possible, but if more power is needed then drop down a level of two (to T2, to base Web2Py or to raw Python).

T2 is used for:

• AAA
• simplified CRUD
• Conflict Detection

We extend the T2 class in modules/sahana.py.
Patches to the framework should be done here.
If they're generic enough then they can be suggested to Massimo for moving upstream to either Web2Py or T2.

We extend the CRUD with a RESTlike controller.
This provides details on how to configure your Model & Controllers. Views may not be required, other than index.html

Mandatory

Each Controller should start like this (to populate the side navigation Menus):

module='module'
# Current Module (for sidebar title)
module_name=db(db.module.name==module).select()[0].name_nice
# List Modules (from which to build Menu of Modules)
modules=db(db.module.enabled=='Yes').select(db.module.ALL,orderby=db.module.menu_priority)
# List Options (from which to build Menu for this Module)
options=db(db['%s_menu_option' % module].enabled=='Yes').select(db['%s_menu_option' % module].ALL,orderby=db['%s_menu_option' % module].priority)

Each function needs to return these values to the view:

return dict(module_name=module_name,modules=modules,options=options)

Optional

List output can be made more functional by this .represent 'widget':

def shn_list_item(table,resource,action,display='table.name',extra=None):
    if extra:
        items=DIV(TR(TD(A(eval(display),_href=t2.action(resource,[action,table.id]))),TD(eval(extra))))
    else:
        items=DIV(A(eval(display),_href=t2.action(resource,[action,table.id])))
    return DIV(*items)

You can use it in models/module.py like:

db.or_organisation.represent=lambda table:shn_list_item(table,resource='organisation',action='display')
db.person.represent=lambda table:shn_list_item(table,resource='person',action='display',display='table.full_name')
db.gis_projection.represent=lambda table:shn_list_item(table,resource='projection',action='display',extra='table.epsg')

Form labels can be set in a translatable manner using:

db.table.field.label=T("label")

Form field can be made to use a TEXTAREA by marking the field as being type 'text':

SQLField('field','text'),

Form field can be made to use a SELECT dropdown by setting the field as a lookup to another table...linked to the 'uuid' field to allow Database Synchronization, but displaying a more user-friendly field (such as 'name'):

SQLField('field',length=64),

db.table.field.requires=IS_NULL_OR(IS_IN_DB(db,'othertable.uuid','othertable.name'))

Form field being required can be marked using:

db.table.field.comment=SPAN("*",_class="req")

Help for a form field can be set using:

A(SPAN("[Help]"),_class="popupLink",_id="tooltip",_title=T("Help Title|This is what this field is for."))

Different Flash styles can be set via:

session.error=T("Unsupported format!")
redirect(URL(r=request,f=resource))

or (in a Multiple Table form.accepts):

response.error=T("Form invalid!")

Supported styles are:

• .warning
• .error
• .information
• .confirmation (Standard T2 Flash messages are usually of this sort so we class them in the same way)

Settings

System-wide settings have their default values set in models/_db.py's shn_default.

Upon 1st run of the system, these settings are pulled into the default_setting table in the database from where they can susequently be edited to configure the running instance.

If these settings are required by all Views then can patch the session to see them in models/_db.py's shn_sessions().
e.g. response.debug is made available to the default layout.html this way.

If you wish to clean out all settings to import afresh, then close down Web2Py & start up in shell mode:

python web2py.py -S sahana -M

Then run:

shn_db_clean(db)

(This function is configured in modules/sahana.py)

Modules can set up their own configuration settings tables in a similar way (e.g. GIS does this)

jQuery Widgets

• Deletable List

Conflict Detection

Sahana is a multi-user system so there is a potential for multiple users to be editing the same record at once.
We use T2 to handle this for us.

Add this field to each table which needs protecting (in models/db.py):

SQLField('modified_on','datetime'), # Used by T2 to do edit conflict-detection

This field is also used in Database Synchronization

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DeveloperGuidelines