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Tips
Table of Contents
Python debugging
- WSGI likes print statements to go to
sys.stderr
notsys.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
- Debug SQL Queries:
- 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()
- Get a Python shell up to explore interactively:
- Insert these statements into your code
- 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:
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:
- Download Images with original filename:
- 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/
HTML, CSS, and Javascript debugging
Each of the major browsers has tools available for viewing HTML page structure and form data, Javascript code, CSS. Some also support Javascript debugging, including setting breakpoints and viewing values in variables.
- Firefox: Install the Firebug plugin. Start Firebug by clicking the bug icon in the upper right. After the tools open in the lower half of the page, load the page you want to debug.
- Chrome: Open the Chrome developer tools with Chrome menu (three bar icon) -> Tools -> Developer tools.
- Internet Explorer: Open the IE developer tools with F12, or Tools (gear icon) -> F12 Developer Tools. Note that you can test behavior of pages under earlier versions of IE by setting your current IE to behave as earlier versions. In the developer tools menu bar, click Browser Mode and select the desired version.
Other tools that may be of interest:
- 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/
- 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, '_');
- Python:
- 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
- Console cd to iframe:
cd(frames[0]) ... cd(top)
jQuery
- http://www.smashingmagazine.com/2008/09/16/jquery-examples-and-best-practices/
- http://www.tvidesign.co.uk/blog/improve-your-jquery-25-excellent-tips.aspx
- http://james.padolsey.com/javascript/things-you-may-not-know-about-jquery/
- http://15daysofjquery.com/
- http://jqueryfordesigners.com/jquery-tabs/
- http://devsnippets.com/reviews/using-jquery-to-style-design-elements-20-impressive-plugins.html
- http://www.mapbender.org/JavaScript_pitfalls:_null,_false,_undefined,_NaN
- http://www.learningjquery.com/2009/03/43439-reasons-to-use-append-correctly
- Web2Py HTML Helper: http://groups.google.com/group/web2py/browse_thread/thread/ec63ee9af3ee659f
- jqGrid in Web2Py: http://groups.google.com/group/web2py/browse_thread/thread/2caa0e4e0161bb8d
Ext
- http://extjs.com/learn/Tutorial:Introduction_to_Ext_2.0
- http://extjs.com/learn/Manual:Basic_Application_Design
- http://extjs.com/learn/Tutorial:Writing_a_Big_Application_in_Ext
- http://extjs.com/forum/showthread.php?t=26728
- http://extjs.com/learn/Ext_FAQ_Debugging
- http://www.extjs.com/blog/2009/05/13/introducing-ext-direct/
HTML/CSS
- http://enhance.qd-creative.co.uk/2008/06/28/the-misunderstood-div/
- http://enhance.qd-creative.co.uk/2008/10/14/7-things-you-can-do-so-your-users-wont-leave/
- Usability: http://www.useit.com
- Progressive Enhancement (better than Graceful Degradation):
SQL
Test queries on multiple databases:
Basics of Design:
- http://www.simple-talk.com/sql/database-administration/ten-common-database-design-mistakes/
- Normalization:
- http://www.sqlteam.com/article/database-design-and-modeling-fundamentals
- http://msdn.microsoft.com/en-us/library/dd129510%28VS.85%29.aspx
Language:
- http://www.intermedia.net/support/sql/sqltut.asp
- http://sqlcourse.com/intro.html
- http://www.w3schools.com/sql/default.asp
- http://www.codinghorror.com/blog/2007/10/a-visual-explanation-of-sql-joins.html
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
- 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: XML, XSL, XPath
We use XSLT (Extensible Stylesheet Language Transformations) to convert external structured data, such as CSV files, spreadsheets, GIS data, and CAP messages into internal S3XML format, and from there to create Eden database entries, and also to export Eden data into external data formats.
XSL Stylesheets are themselves XML documents that specify a conversion between one data format and another. XPath (XML Path Language) is used to select elements from the source document to act on.
The stylesheets for various data formats are found in the directory: eden/static/formats
Support for XSLT is provided by lxml, which is a Python wrapper for libxml2 and libxslt. This currently supports the XML 1.0 standard, not 2.0, and there are functions available in 2.0 that are not in 1.0, so be aware of this when you are consulting XML / XSLT references.
Online references
- W3 standards
- MSDN XSLT Reference
- Dave Pawson's tutorials
Books
- Evan Lenz, XSLT 1.0 Pocket Reference, O'Reilly
- Michael Kay, XSLT Programmer's Reference, WROX Press (note link is to a later edition that covers XSLT 2.0)
Tools
Try out your xsl stylesheets with: xsltransform.py
Visualization
- http://www.ted.com/talks/hans_rosling_shows_the_best_stats_you_ve_ever_seen.html
- http://www.ted.com/talks/david_mccandless_the_beauty_of_data_visualization.html
Misc
- Bugmail add-on for Thunderbird: https://addons.mozilla.org/en-US/thunderbird/addon/9584