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DeveloperGuidelines

Tips

Table of Contents

Python debugging

WSGI likes print statements to go to sys.stderr not sys.stdout: http://code.google.com/p/modwsgi/wiki/DebuggingTechniques
use Web2Py shell: http://www.vimeo.com/879939
use IPython for interactive exploration (on Windows, install PyReadline)
use FirePy to see logging output to Console (to view with Firebug)
Log to a File: http://groups.google.com/group/web2py/browse_thread/thread/e20d0bd2e542aa14
Debug Tools: http://docs.python.org/library/debug.html

Use Inspect to check which function called the one you're troubleshooting:

import inspect
curframe = inspect.currentframe()
calframe = inspect.getouterframes(curframe, 2)
#print 'caller name:', calframe[1][3]
s3_debug('caller name:%s' % calframe[1][3])

Debug SQL Queries:

vi gluon/dal.py
class BaseAdapter()
    def select():
        def response(sql):
            if "searchphrase" in sql:
                print >> sys.stderr, "Query: %s" % query
                print >> sys.stderr, "SQL: %s" % sql

Python Debugging Techniques
- Insert these statements into your code
  - Get a Python shell up to explore interactively: import code; code.interact(locals=locals()
  - Get a full stack trace: import pdb; pdb.set_trace()
winpdb: http://groups.google.com/group/web2py/msg/ee46125b7c93fdd4
WingIDE: http://www.wingware.com/
- Using with Web2Py: http://www.wingware.com/doc/howtos/web2py
Eclipse IDE
Unicode:
- "Decode early, Unicode everywhere, Encode late": http://farmdev.com/talks/unicode/
- http://boodebr.org/main/python/all-about-python-and-unicode
Python Design Patterns:
- http://www.youtube.com/watch?v=Er5K_nR5lDQ
- http://videolectures.net/youtube_martelli_python/

Reserved Keywords

'request' -> web2py internal use
'key' as a db row name -> MySQL confuses it with internal keyword KEY
http://dev.mysql.com/doc/mysqld-version-reference/en/mysqld-version-reference-reservedwords-5-0.html
http://www.postgresql.org/docs/8.1/static/sql-keywords-appendix.html

Web2Py

Web2py Internals and Tips
http://web2py.com/examples/default/docs
Prevent HTML tags being escaped in views: {{=XML("<p>Not escaped!</p>")}}
HTML Helpers: http://web2py.com/AlterEgo/default/show/217
Arbitrary HTML tags using TAG, e.g. TAG.LEGEND('a','b',_c='d')
HTML Helpers can be navigated/manipulated like the DOM: http://groups.google.com/group/web2py/browse_thread/thread/ac045f3b1d3846d9
https://web2py.com/web2py_wiki/default/wiki/tips
https://web2py.com/web2py_wiki/default/wiki/widgets
Pagination:
- Basic server-side pagination: http://web2py.com/AlterEgo/default/show/95
- Grid to replace SQLTABLE with server-side pagination included: http://www.web2pyslices.com/main/slices/take_slice/39
New syntax for low-level database record create/update/delete: http://groups.google.com/group/web2py/browse_thread/thread/d79a6e52824d4221
Default field values with crud.create(): http://groups.google.com/group/web2py/browse_thread/thread/717e2349f0f8e93d
Edit multiple records at once: http://groups.google.com/group/web2py/browse_thread/thread/401b4c192871194c/a96cc8c7923a8565#
Prevent multiple concurrent logins: http://groups.google.com/group/web2py/browse_thread/thread/4e1c62a0d9255160
Process uploaded files manually (e.g. to unzip KMZ): http://groups.google.com/group/web2py/browse_thread/thread/63809c06cac3b0d5
Access DB models from a Python script: http://groups.google.com/group/web2py/browse_thread/thread/147b47069a9c1ea2
Custom Forms
- Debug by setting the return to just a plain dict() (=> can read values of vars in 'request')
- Latest code method: http://groups.google.com/group/web2py/browse_thread/thread/1d7c1e31b5f66534
  - Suggested workflow for customising HTML: http://groups.google.com/group/web2py/browse_thread/thread/95e571e49b7d77ed/8c998b226f5a0437
- less retyping of code in view using SQLFORM extensions: http://groups.google.com/group/web2py/browse_thread/thread/2d8cc57352d158bd
- Simple version: http://groups.google.com/group/web2py/browse_thread/thread/7245cab0df469d5f
- Alternate approach: http://www.wellbehavedsystems.co.uk/web2py/examples/
- Helper field2html(): http://groups.google.com/group/web2py/browse_thread/thread/1012c11c977aa05e
- Multiple per page: http://groups.google.com/group/web2py/browse_thread/thread/57e452d186d48fa4
- Values retrieved from DB are stored for re-referencing: http://mdp.cti.depaul.edu/AlterEgo/default/show/205
- Summary of MVC options: http://groups.google.com/group/web2py/browse_thread/thread/7da38e0d32d01076
- form.accepts AJAX submission: http://groups.google.com/group/web2py/browse_thread/thread/e583a1e377cc7dea
Lambda tricks: http://p-nand-q.com/python/stupid_lambda_tricks.html
THIS_NOT_IN_DB custom validator: http://groups.google.com/group/web2py/browse_thread/thread/27b14433976c0540?pli=1
IS_IN_DB (...,order_by=...): http://groups.google.com/group/web2py/browse_thread/thread/5fe6e343d115590d/2a8c38fccb2cf3cf#2a8c38fccb2cf3cf

Multiple field validation example:

db.Wedding.location.requires = [IS_NOT_EMPTY(), IS_NOT_IN_DB(db(db.Wedding.weddingDateTime == request.vars.weddingDateTime), 'Wedding.location', error_message="Date/Time for Venue is Booked")]

CGI co-existence: http://groups.google.com/group/web2py/browse_thread/thread/1520b84d144f0b0c
Inline Images in T2 CRUD: http://groups.google.com/group/web2py/browse_thread/thread/d954bf883baf7adc/3b55a819b425a741
PIL to create thumbnails:
- http://groups.google.com/group/web2py/browse_thread/thread/3523f9a12edc6836
- http://groups.google.com/group/web2py/browse_thread/thread/380cfb61a1fa1596
Download Images with original filename:
- http://groups.google.com/group/web2py/browse_thread/thread/484a2d04bdd7606f
- http://groups.google.com/group/web2py/browse_thread/thread/1df80dbf52d401fb
TEXTAREA options: http://groups.google.com/group/web2py/browse_thread/thread/482ecab0878689d5
nicEdit integration: http://groups.google.com/group/web2py/msg/ff491af9382f6c39
Multi-column unique constraint: http://groups.google.com/group/web2py/browse_thread/thread/f5ab94cc7d511e0b
Modified preorder Tree Traversal (for large Hierarchical trees): http://groups.google.com/group/web2py/browse_thread/thread/70efddab62dfe73
Hierarchical References: http://groups.google.com/group/web2py/browse_thread/thread/a4f57635d4a05f83
JSON datetime serialization: https://web2py.com/web2py_wiki/default/wiki/JSONdatetime
Enter key in ajaxified forms: http://groups.google.com/group/web2py/browse_thread/thread/bae7b19ff35b896b#
Limiting access to a controller function to just certain IPs: http://groups.google.com/group/web2py/msg/df000860c707d3d3
Auto-complete (for when Dropdowns get too long):
- AutoComplete guidelines proposal
- use the ajaxS3 calls: getS3, getJSONS3, or postS3
- use the IS_ONE_OF_EMPTY validator
- http://trac.sahanapy.org/browser/views/msg/email_outbox_create.html
- http://groups.google.com/group/web2py/browse_thread/thread/e1034df0091b5bfd
- http://groups.google.com/group/web2py/browse_thread/thread/f6e0170273b14241
- http://bassistance.de/jquery-plugins/jquery-plugin-autocomplete/ (Also: http://plugins.jquery.com/project/autocompletex)
- http://dyve.net/jquery/?autocomplete (Older version: http://www.pengoworks.com/workshop/jquery/autocomplete.htm)
- http://code.google.com/p/js-autocomplete/
- http://github.com/ReinH/jquery-autocomplete/tree/master (Also: http://plugins.jquery.com/project/jq-autocomplete)
- http://plugins.jquery.com/project/YA_AutoComplete
EPB: http://groups.google.com/group/web2py/browse_thread/thread/c090560680b65db2
Implementing Plone's Indexing & Workflow: http://groups.google.com/group/web2py/browse_thread/thread/496edd88f6298653
Importing Legacy Data: http://groups.google.com/group/web2py/browse_thread/thread/5bd8f85b21444858
Upload progress: http://www.web2pyslices.com/main/slices/take_slice/10
Use the StatusBar for dynamic status updates
http://code.google.com/p/web2pyorm/

CSS & Javascript debugging

use Firebug: http://code.google.com/support/bin/answer.py?answer=77412&topic=12044
use Visual Event to see which events are active.
use Venkman: http://www.mozilla.org/projects/venkman/
use Fiddler for compressed files: http://www.yuiblog.com/blog/2008/06/27/fiddler
http://pastebin.me (allows edits of HTML & previews)
http://jsfiddle.net (allows edits of JS & previews)
http://yura.thinkweb2.com/domlint/
- http://www.jslint.com/lint.html
IE6 cheatsheet: http://www.virtuosimedia.com/tutorials/ultimate-ie6-cheatsheet-how-to-fix-25-internet-explorer-6-bugs

JavaScript

http://trac.openlayers.org/wiki/Documentation#BeforeGettingStarted--TheTechnologiesBehindOpenLayers
http://eloquentjavascript.net
Dynamically load additional JS: http://unixpapa.com/js/dyna.html
array.join instead of string concatenation (& other tips)
Ensure variable names use only Word characters:
- Python: variable_name = re.sub('\W', '_', string)
- JS: var RE_JSVAR = new RegExp("\W", "g"); var variable_name = string.replace(RE_JSVAR, '_');
Loop timings: http://blogs.sun.com/greimer/entry/best_way_to_code_a
Closures: http://www.javascriptkit.com/javatutors/closures.shtml
Memory Leaks: http://www.javascriptkit.com/javatutors/closuresleak/index.shtml

jQuery

Ext

HTML/CSS

SQL

Test queries on multiple databases:

http://sqlfiddle.com

Basics of Design:

Language:

More Advanced:

http://www.tomjewett.com/dbdesign/dbdesign.php?page=intro.html
http://www.w3schools.com/Sql/sql_join.asp
http://en.wikipedia.org/wiki/Join_(SQL
http://www.plus2net.com/sql_tutorial/sql_linking_table.php
http://en.wikipedia.org/wiki/Entity-attribute-value_model
- http://pypi.python.org/pypi/eav-django
Object-Relational Mapping: http://www.objectmatter.com/vbsf/docs/maptool/ormapping.html
Modified preorder Tree Traversal (for large Hierarchical trees): http://www.sitepoint.com/print/hierarchical-data-database/
GAE Many<>Many: http://arbingersys.blogspot.com/2008/04/google-app-engine-better-many-to-many_30.html
Django ORM & JOINs: http://slott-softwarearchitect.blogspot.com/2009/07/object-models-and-relational-joins.html
Especially useful for USB (minimise disk access): http://web.utk.edu/~jplyon/sqlite/SQLite_optimization_FAQ.html

XSLT

DeveloperGuidelines#XSLT

Visualization

Misc

Bugmail add-on for Thunderbird: https://addons.mozilla.org/en-US/thunderbird/addon/9584

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