wiki:DeveloperGuidelines

Version 166 (modified by Fran Boon, 11 years ago) ( diff )

Closure

Developer Guidelines

Development Process

Development Enviroment

Framework

User Interface

Other Resources

  • Tips - useful links to explore

Python

Indentation matters (use 4 spaces instead of Tabs)

More details at: DeveloperGuidelinesCodeConventions

Web2Py

This is an MVC environment (like Rails & Django. Django polls tutorial conversion course).

Web2Py can work at several different levels of abstraction.
The Sahana Eden framework (S3) is built on Web2Py's Auth/Crud classes in tools.py (with some remnants of the older T2), however sometimes we need more control therefore need to drop down a level or two.

Recommend using the CLI to try out code snippets in the Web2Py environment (gluon, Model):

python web2py.py -S eden -M

Can execute a controller to be able to access its functions using:

execfile("applications/eden/controllers/mycontroller.py", globals())

Web2Py can be extended through Plugins & also has a recipes site.

Tutorial

This tutorial was given at SahanaCamp 1.1 in Taiwan:

Model

Defines databases in: /models/module.py

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 appropriately:
000_config.py, 01_crud.py, 02_pr.py, 03_gis.py, etc

Controller

Python functions in /controllers/module.py
e.g.

   def list_records():
       items = crud.select(table)
       return dict(items=items)

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/*_ajax.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

Static CSS/Javascript files are stored in /static

Javascript

  • S3 includes a cross-browser debug utility (only shows up when ?debug=1):
    s3_debug('message', value);
    

All global variables should be in the S3 namespace:

The Module Pattern should be used to protect private variables:

Deployment

Browsers default to only downloading 2 files from the same origin at a time, so many files is very slow on high latency links.

We therefore consolidate into fewer, larger files when running in Production mode.

Since GIS is a specialised app which requires many files, it's JS is loaded separately when required.

The build script is static/scripts/tools/build.sahana.py

There is also a convenience wrapper for Windows to run this & also move results into their respective locations: static/scripts/tools/build.cmd

Need to remove the '@' from '@requires' in header of /static/scripts/S3/jquery.form.js as we need to compress this without the main file.

Our build process is based on the one used by OpenLayers

This uses Google's Closure compiler to compress the JS. This is done using their web service, however for OpenLayers itself we need to download the jar file & place in the tools folder since this is over 1Mb:

ToDo: Investigate using other options instead:

ToDo: Investigate using LabJS to download/execute scripts asynchronously:

Mobile

  • Android - Developer Guidelines for the Android client
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