Sahana introduction to the code v2
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- The document discusses Sahana Eden, an open-source emergency management system. It provides an overview of the model-view-controller framework and describes how to set up the software and develop new modules. - Instructions are given for building a sample Vehicle Tracking System module, including defining models, controllers, views and integrating it with the core system. - Techniques for joining resources across multiple tables, internationalization, mapping and more are demonstrated through this example.
![Sahana Eden: Emergency Development Environment 2 July 2010, Sahana Camp Fran Boon [email_address]](https://image.slidesharecdn.com/sahana-introductiontothecodev2-100811174028-phpapp02/85/sahana-introduction-to-the-code-v2-1-320.jpg)
![Stack Overview ,[object Object],Client Browser Eclipse Firebug Sahana Eden (S3) Web2Py Python HTML JavaScript CSS](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
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Sahana introduction to the code v2
- 1. Sahana Eden: Emergency Development Environment 2 July 2010, Sahana Camp Fran Boon [email_address]
- 6. Tea
- 11. JavaScript
- 29. Lunch
- 48. URL(r=request, a= application , c= controller , f= function , args=[], vars={})
- 53. Tea
- 69. Show me the Map!
- 77. S3 is built on Web2Py REST CRUD SQLFORM FORM
- 82. End
- 87. BluePrint: Messaging Open Data Kit JavaRosa
Notas del editor
- S3 is a codename for Sahana Eden Server & Client can be on the same machine Each part needs to be debugged separately: Eclipse works well for the Server-side Python, whilst Firebug is excellent for the generated HTML/CSS/JavaScript JavaScript libraries we use include jQuery & ExtJS
- You can install the software from the server or from provided packs on USB flash drives Users of other Linux distributions are without step-by-step help currently – contributions welcomed
- http://eden.sahanafoundation.org/wiki/DeveloperGuidelinesEclipse Launch Eclipse tick Use this as the default & do not ask again, Next Right-click on ‘Resource’ in top-right & close Window menu | Open Perspective | Other | Debug Window menu | Open Perspective | Other | PyDev Open the ‘Debug’ perspective. Window menu | Show View | Expressions Set up the Python Interpreter: Window > Preferences > PyDev > Interpreter - Python New, Browse to python26/python.exe, OK, OK Add a new PyDev Project: File > New > Project > PyDev Project > Next untick Use Default Browse to the web2py directory Give the project a name: eden, Next untick "Create default 'src' folder and add it to the pythonpath" Debug Configuration: Run > Debug Configurations > Python Run Name: Sahana Eden Project: Browse to eden Main Module: Browse to web2py.py Arguments tab: Program Arguments: -a password Apply, Debug unblock in Windows Firewall
- Look around the filesystem in web2py/applications/eden folder Similar layout structure to other MVC frameworks, such as Ruby-on-Rails
- JavaScript which doesn’t require server-side parsing put into static Python Libraries available: System Python, Web2Py, Eden (S3*)
- Remember that after server-side Python finishes, we still have a lot of possibilities client-side with JavaScript.
- Minimise the time taken to process Manage dependencies No need to import most of the libraries in ‘gluon/’
- Deleted Columns / Tables simply Ignored
- Take a look at them now Remember that execution order is defined by alphabetical order
- Take a look at them now
- Take a look at them now
- For each of these, you should find at least 1 Model, a single Controller & a folder containing 1 or more Views
- Sahana Eden is Resource-centric
- Web Services, Mash-ups
- Create a new file in the Models folder called ‘vts.py’ & type in the text above. # Text after this symbol is a comment & is ignored If you make a mistake, then the Ticketing system should catch the error & let you know what you did wrong.
- No need to create a manual routes entry, unlike other frameworks, like Django
- Create a new file in the Controllers folder called ‘vts.py’ & type in the text above.
- Note that you’ll need to Register yourself as a user on the system before you’re allowed to create a resource. The 1 st user to register gets the Administrator role by default.
- This should be available as a script or an alias ‘w2p’
- No need to learn another macro language Can Extend just a single other file Can Include many others
- These defaults are why we didn’t need any views for our application.
- Create a new folder in the views folder called ‘vts’ & inside that put a new file ‘vehicle_list_create.html’. Type in the text above. Refresh the vehicle page to see the new text: http://127.0.0.1:8000/eden/vts/vehicle
- All user-visible text should be localised by calling through T() Amend your view & then update the languages files - the string should now be visible in the list of strings to translate
- HTML tags shouldn’t be in the translatable strings If concatenating with strings, need to str() the LazyT 1 st . Tstr() is a convenience function defined within Eden
- Open the About page & browse the variables We store our S3 variables in response.s3.*, session.s3.* so as not to pollute the Web2Py namespace
- Unique=True is a SQL-level constraint. Open your vts.py from the models directory & add the extra code above. Try to enter bad data: tickets
- Validators are DAL-level constraints which produce nice error messages instead of tickets! Validators provide server-side validation & some also provide client-side rendering & validation Add the extra code above to your file & now add bad data to see the difference.
- Fields default to type ‘string’. ‘ date’ is the SQL-level field type & also provides the class in the HTML which means we get a date widget Add the extra code above to your file & refresh the page, now enter a date.
- Add the extra code above to your file & refresh the page to see the default value
- Add this to your controller & try it out
- You can check out the languages file again, if you wish: http://127.0.0.1:8000/admin/default/design/eden#languages Update all languages
- Add this to your controller & try it out Comment is rendered as ‘column3’ (although can be moved using ‘formstyle’)
- Try them out…copy/paste from another controller & then edit…see what effect this has on your module.
- Can provide your own custom buttons here – shn_action_buttons are just the common ones. See definition in models/00_utils.py Copy this into your controller file & see what effect this has on your module. This REST ‘post-processor’ has a companion ‘pre-processor’ available too (you can see org.py organsiation() for an example)
- URL() is an example of an HTML ‘Helper’ object
- Add this text to the file 000_config.py in the models folder. Navigate to the home page to see the module appear both there & on the menu. Try navigating to the module. Module Type 10 means appears in the ‘more’ section of the default modules menu. (Most deployments will create a fully-customised menu anyway)
- Add this text to your controller file & now open the module. “ Custom View” is a Doc String One should be added to all functions for automatic documentation generators & interactive browsing of docs You can try this out in the Interactive Shell: w2p execfile("applications/eden/controllers/vts.py", globals()) help(index)
- Create a file called ‘index.html’ inside the views/vts folder See plain HTML being interspersed with the server-side parsed Python Look at another module’s index.html What’s bad about this index?
- Add this text to your controller (outside the functions – e.g. at the top) & see what effect this has on your module.
- Copt this text into your model. Note the use of string substitution to define the tablename
- Tells SQL that these fields are ‘reference’ fields (i.e. Foreign Keys) - They store integers which are a pointer to the ID field in the other tables.
- Copy this text into your Model & refresh the presence page Reusable field defined in models/03_gis.py Includes additional useful configuration such as .requires & .represent
- Copt this text into your controller. Try it out. Note the automation of the resource name to minimise the editing after copy/paste of new functions
- Copy this text into your model & see what it does for the page IS_ONE_OF() will provide us a dropdown showing license plates, even though we actually store the ID. This is an S3 validator which extends Web2Py’s IS_IN_DB() to support the ‘deleted’ status & also allow the use of lambdas as formatting options.
- We can add additional fields into the link table.
- Google: web2py dal Try these out in the Web2Py shell Don’t take effect until you db.commit() Beware locking with Sqlite! (e.g. cron tasks) Wipe DB if developing a lot For Production, split Dev/UAT/Prod instances so that you can plan Data Migrations (Live migrations works in most cases, but some do need manual scripts still – not a complete ‘Get out of jail free’).
- Don’t take effect until you db.commit()
- IS_ONE_OF provides the representation in the dropdown table.field.represent provides the representation in Display/List views Optimise the query – we know we only want a single record & a single field from that record
- Add this to your model underneath the definition of the Presence table & try out the URL. No need for dedicated presence() controller
- Add this Resource Header to your Controller.
- Then plug it into the Controller Take another look
- Add a Vehicle Presence & view it on the Map
- Can automate the collection of the location information if it makes sense
- Whilst we spend a lot of time updating developer documentation, the actual codebase always moves faster, so the source is always the most authoritative source of information.
- Web2Py source code very accessible – small enough to be able to grasp the whole thing after not too long FORM defined in gluon/html.py: Dumb HTML elements SQLFORM defined in gluon/sqlhtml.py: Self-processing forms which update the database CRUD defined in gluon/tools.py: Wrappers around SQLFORM REST defined in modules/s3xrc.py: RESTful interface & XML representations If you drop down a level, then need to do things more manually & need to take care of framework issues yourself.
- NB Don’t redirect in an onaccept or you’ll break bulk XML imports!
- XSLT stored in static
- More effort at 1 st but makes subsequent resources much faster to copy/paste
- S3’s REST Controller is built on top of Web2Py’s ‘Crud’ controller, so we can also use it’s controls NB Be careful using next or you’ll break bulk XML imports!
- Only want this in interactive views, not JSON/XML & not in Popups either
- We wrap the underlying CRUD functions within REST