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pyramid.events

Functions

subscriber(*ifaces)[source]

Decorator activated via a scan which treats the function being decorated as an event subscriber for the set of interfaces passed as *ifaces to the decorator constructor.

For example:

from pyramid.events import NewRequest
from pyramid.events import subscriber

@subscriber(NewRequest)
def mysubscriber(event):
    event.request.foo = 1

More than one event type can be passed as a constructor argument. The decorated subscriber will be called for each event type.

from pyramid.events import NewRequest, NewResponse
from pyramid.events import subscriber

@subscriber(NewRequest, NewResponse)
def mysubscriber(event):
    print event

When the subscriber decorator is used without passing an arguments, the function it decorates is called for every event sent:

from pyramid.events import subscriber

@subscriber()
def mysubscriber(event):
    print event

This method will have no effect until a scan is performed against the package or module which contains it, ala:

from pyramid.config import Configurator
config = Configurator()
config.scan('somepackage_containing_subscribers')

Event Types

class ApplicationCreated(app)[source]

An instance of this class is emitted as an event when the pyramid.config.Configurator.make_wsgi_app() is called. The instance has an attribute, app, which is an instance of the router that will handle WSGI requests. This class implements the pyramid.interfaces.IApplicationCreated interface.

Note

For backwards compatibility purposes, this class can also be imported as pyramid.events.WSGIApplicationCreatedEvent. This was the name of the event class before Pyramid 1.0.

class NewRequest(request)[source]

An instance of this class is emitted as an event whenever Pyramid begins to process a new request. The event instance has an attribute, request, which is a request object. This event class implements the pyramid.interfaces.INewRequest interface.

class ContextFound(request)[source]

An instance of this class is emitted as an event after the Pyramid router finds a context object (after it performs traversal) but before any view code is executed. The instance has an attribute, request, which is the request object generated by Pyramid.

Notably, the request object will have an attribute named context, which is the context that will be provided to the view which will eventually be called, as well as other attributes attached by context-finding code.

This class implements the pyramid.interfaces.IContextFound interface.

Note

As of Pyramid 1.0, for backwards compatibility purposes, this event may also be imported as pyramid.events.AfterTraversal.

class NewResponse(request, response)[source]

An instance of this class is emitted as an event whenever any Pyramid view or exception view returns a response.

The instance has two attributes:request, which is the request which caused the response, and response, which is the response object returned by a view or renderer.

If the response was generated by an exception view, the request will have an attribute named exception, which is the exception object which caused the exception view to be executed. If the response was generated by a ‘normal’ view, this attribute of the request will be None.

This event will not be generated if a response cannot be created due to an exception that is not caught by an exception view (no response is created under this circumstace).

This class implements the pyramid.interfaces.INewResponse interface.

Note

Postprocessing a response is usually better handled in a WSGI middleware component than in subscriber code that is called by a pyramid.interfaces.INewResponse event. The pyramid.interfaces.INewResponse event exists almost purely for symmetry with the pyramid.interfaces.INewRequest event.

class BeforeRender(system, rendering_val=None)[source]

Subscribers to this event may introspect and modify the set of renderer globals before they are passed to a renderer. This event object iself has a dictionary-like interface that can be used for this purpose. For example:

from pyramid.events import subscriber
from pyramid.events import BeforeRender

@subscriber(BeforeRender)
def add_global(event):
    event['mykey'] = 'foo'

An object of this type is sent as an event just before a renderer is invoked (but after the – deprecated – application-level renderer globals factory added via pyramid.config.Configurator.set_renderer_globals_factory, if any, has injected its own keys into the renderer globals dictionary).

If a subscriber adds a key via __setitem__ that already exists in the renderer globals dictionary, it will overwrite the older value there. This can be problematic because event subscribers to the BeforeRender event do not possess any relative ordering. For maximum interoperability with other third-party subscribers, if you write an event subscriber meant to be used as a BeforeRender subscriber, your subscriber code will need to ensure no value already exists in the renderer globals dictionary before setting an overriding value (which can be done using .get or __contains__ of the event object).

The event has an additional attribute named rendering_val. This is the (non-system) value returned by a view or passed to render* as value. This feature is new in Pyramid 1.2.

For a description of the values present in the renderer globals dictionary, see System Values Used During Rendering.

See also pyramid.interfaces.IBeforeRender.

update(E, **F)

Update D from dict/iterable E and F. If E has a .keys() method, does: for k in E: D[k] = E[k] If E lacks .keys() method, does: for (k, v) in E: D[k] = v. In either case, this is followed by: for k in F: D[k] = F[k].

clear() → None. Remove all items from D.
copy() → a shallow copy of D
static fromkeys(S[, v]) → New dict with keys from S and values equal to v.

v defaults to None.

get(k[, d]) → D[k] if k in D, else d. d defaults to None.
has_key(k) → True if D has a key k, else False
items() → list of D's (key, value) pairs, as 2-tuples
iteritems() → an iterator over the (key, value) items of D
iterkeys() → an iterator over the keys of D
itervalues() → an iterator over the values of D
keys() → list of D's keys
pop(k[, d]) → v, remove specified key and return the corresponding value.

If key is not found, d is returned if given, otherwise KeyError is raised

popitem() → (k, v), remove and return some (key, value) pair as a

2-tuple; but raise KeyError if D is empty.

setdefault(k[, d]) → D.get(k,d), also set D[k]=d if k not in D
values() → list of D's values
viewitems() → a set-like object providing a view on D's items
viewkeys() → a set-like object providing a view on D's keys
viewvalues() → an object providing a view on D's values

See Using Events for more information about how to register code which subscribes to these events.

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