88 lines
3.0 KiB
Python
88 lines
3.0 KiB
Python
import cherrypy
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from Validate import Validation_error
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# module-level variable that, when set to a view, overrides the view for all exposed methods. used
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# by unit tests
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view_override = None
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def expose( view = None, rss = None ):
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"""
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expose() can be used to tag a method as available for publishing to the web via CherryPy. In
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other words, methods that are not exposed cannot be accessed from the web.
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The expose() method itself is evaluated where it is used as a decorator, which just puts the view
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variable into the enclosing scope of the decorate() function and returns decorate() to be used as
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the actual decorator.
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Example usage:
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@expose( view = Json )
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def method(): pass
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"""
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def decorate( function ):
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"""
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When the method being decorated is invoked, its decorator gets invoked instead and is supposed
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to return a new function to use in place of the method being decorated (or a modified version
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of that function). In this case, the decorator is our decorate() function, and the function it
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returns is the render() function. decorate()'s first argument is the method being decorated.
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"""
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def render( *args, **kwargs ):
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"""
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render() pretends that it's the method being decorated. It takes the same arguments and then
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invokes the actual method being decorated, passing in those arguments.
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With whatever result it gets from calling that method, render() invokes the view from the
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outer scope to try to render it. It then results that rendered result.
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"""
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result = {}
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# if rss was requested, and this method was exposed for rss, then use rss as the view
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if u"rss" in kwargs:
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del kwargs[ u"rss" ]
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use_rss = True
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else:
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use_rss = False
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# kwarg names must be of type str, not unicode
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kwargs = dict( [ ( str( key ), value ) for ( key, value ) in kwargs.items() ] )
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# try executing the exposed function
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try:
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result = function( *args, **kwargs )
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except Validation_error, error:
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result = dict( name = error.name, value = error.value, error = error.message )
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redirect = result.get( u"redirect", None )
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# try using the supplied view to render the result
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try:
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if view_override is None:
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if rss and use_rss:
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cherrypy.response.headers[ u"Content-Type" ] = u"application/xml"
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return unicode( rss( **result ) )
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else:
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return unicode( view( **result ) )
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else:
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return unicode( view_override( **result ) )
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except:
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if redirect is None:
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print "error: %s" % result
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raise
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# if that doesn't work, and there's a redirect, then redirect
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del( result[ u"redirect" ] )
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from urllib import urlencode
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if result == {}:
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raise cherrypy.HTTPRedirect( u"%s" % redirect )
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else:
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url_args = urlencode( result )
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raise cherrypy.HTTPRedirect( u"%s?%s" % ( redirect, url_args ) )
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render.exposed = True
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return render
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return decorate
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