DeveloperGuidelines

== Web Services ==

We want to be able to access data from the database exported as JSON for easy use within Javascript clients.

This can be done by simply calling the [https://trac.sahana3.org/wiki/BluePrintREST RESTlike controller] with the var {{{?format=json}}}:
{{{
/sahana/module/resource?format=json           # Lists all records of this resource
/sahana/module/resource/id?format=json        # Display record with record.id==id
/sahana/module/resource/create?format=json    # ToDo
/sahana/module/resource/update/id?format=json # ToDo
}}}

The underlying functions are very easy within Web2Py since 1.55:
{{{
def display_json():
    "Designed to be called via AJAX to be processed within JS client."
    list=db(db.table.id==t2.id).select(db.table.ALL).json()
    response.view='plain.html'
    return dict(item=list)
}}}

----
Another approach (from T3: http://groups.google.com/group/web2py/browse_thread/thread/9ec8b06b158adb75):
Model:
{{{
from gluon.storage import Storage
settings=Storage()
settings.rss_procedures=[]
settings.exposed_procedures=[]
settings.xmlrpc_procedures=[]
settings.json_procedures=[]
def rss(f):
    settings.rss_procedures.append(f.__name__)
    return f
def expose(f):
    settings.exposed_procedures.append(f.__name__)
    return f
def json(f):
    settings.json_procedures.append(f.__name__)
    return f
def xmlrpc(f):
    settings.xmlrpc_procedures.append(f.__name__) 
}}}
Controller:
{{{
def rss():
    if request.args and request.args[0] in settings.rss_procedures:
       feed=eval('%s(*request.args[1:],**dict
(request.vars))'%request.args[0])
    else:
       t2._error()
    import gluon.contrib.rss2 as rss2
    rss = rss2.RSS2(
       title=feed['title'],
       link = feed['link'],
       description = feed['description'],
       lastBuildDate = feed['created_on'],
       items = [
          rss2.RSSItem(
            title = entry['title'],
            link = entry['link'],
            description = entry['description'],
            pubDate = entry['created_on']) for entry in feed
['entries']]
       )
    response.headers['Content-Type']='application/rss+xml'
    return rss2.dumps(rss)

def run():
    if request.args and request.args[0] in
settings.exposed_procedures:
       return eval('%s(*request.args[1:],**dict
(request.vars))'%request.args[0])
    return 'Not Authorized'

def xmlrpc():
    methods=[eval(x) for x in settings.xmlrpc_procedures]
    return response.xmlrpc(request,methods)

def json():
    if request.args and request.args[0] in settings.json_procedures:
       import gluon.contrib.simplejson as sj
       return sj.dumps(eval('%s(*request.args[1:],**dict
(request.vars))'%request.args[0]))
    return 'Not Authorized' 
}}}
----
Another approach (using [http://pyjs.org Pyjamas]):

* http://mdp.cti.depaul.edu/AlterEgo/default/show/203

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DeveloperGuidelines