wiki:DeveloperGuidelines

Version 123 (modified by becky, 14 years ago) ( diff )

added a link to new tutorial guide for developers

Table of Contents

  1. Install a Development Environment
  2. Python
  3. Web2Py
  4. Tutorial
    1. Model
    2. Controller
    3. View
  5. Javascript
  6. Developer Guidelines
  7. Mobile

Developer Guide

Install a Development Environment

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);

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 & CSS are 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 MapFish (which is built on the one used by OpenLayers)

ToDo: Investigate using other options instead:

Developer Guidelines

  • Tips - useful links to explore

TranslatedPages

Mobile

Note: See TracWiki for help on using the wiki.