DeveloperGuidelinesTips

Python

• Slow start
  • ​http://openbookproject.net/thinkcs/python/english2e/
• Quick start
  • ​http://diveintopython.org/
• v.Quick start!
  • Indentation matters (use 4 spaces instead of Tabs)
  • OOP - everything is an object

Web2Py

• ​http://mdp.cti.depaul.edu/examples/static/cookbook.pdf
• ​http://mdp.cti.depaul.edu/examples/static/web2py_cheatsheet.pdf
• ​https://mdp.cti.depaul.edu/web2py_wiki/default/wiki/tips

This is an MVC environment (like Rails & Django).

Model

Defines databases in: /models/module.py (equivalent of inst/mysql-dbcreate.sql)

The Models are loaded 1st within Web2Py processing, before the controllers. So you can import any global modules/set any global variables here. The Models are imported in alphabetical order, so we load the files which other modules depend on 1st, hence naming them with an underscore: _db.py, _gis.py

Controller

Python functions in /controllers/module.py

e.g.

   def list_records():
       list=t2.itemize(table)
       return dict (list=list)

View

HTML/Javascript templates in /views/module/function.html

• these are normal HTML/JS files with the ability to add in Python code (e.g. variables) surrounded by brackets: {{ interpreted python here }}
• there should be an .html file available for each function in the module (name normally being the same as the function)
• these normally inherit from views/layout.html which also includes the Javascript from views/web2py_ajax_t2.html
• if there is no view defined then a default view will be displayed, which will show the values of all the data it can see, but not be formatted nicely

CSS/Javascript files are stored in /static (equivalent of www/res)

T2

This plugin is used for AAA & simplified CRUD (inc Conflict Detection)

• ​http://mdp.cti.depaul.edu/examples/static/t2.pdf

We extend the T2 class in modules/sahana.py

Conflict Detection

Sahana is a multi-user system so there is a potential for multiple users to be editing the same record at once.

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

Sahana3 Framework

These are the bits that we use on top of Web2Py to give the Sahana look & feel:

Populate the side navigation Menus by adding this to each controller:

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)

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."))

DeveloperGuidelinesDeletableList

Options fields

Sahana2 has a generic 'field_options' table for storing Options fields.

Sahana3 uses a separate table for each lookup list.

How to add a new Module?

DeveloperGuidelinesNewModule

Web Services

DeveloperGuidelinesWebServices

GIS

DeveloperGuidelinesGIS

Testing

DeveloperGuidelinesTesting

Using Bzr

DeveloperGuidelinesBzr

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