1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
|
.. _hooks_chapter:
Using ZCML Hooks
================
ZCML "hooks" can be used to influence the behavior of the
:mod:`repoze.bfg` framework in various ways. This is an advanced
topic; not many people will want or need to do any of these things.
Changing the request factory
----------------------------
You may change the class used as the "request factory" from within the
:mod:`repoze.bfg` ``Router`` class (the ``Router`` class turns the
WSGI environment into a "request" object which is used ubiquitously
throughout :mod:`repoze.bfg`). The default "request factory" is the
class ``webob.Request``. You may change it by placing the following
ZCML in your ``configure.zcml`` file.
.. code-block:: xml
:linenos:
<utility provides="repoze.bfg.interfaces.IRequestFactory"
component="helloworld.factories.request_factory"/>
Replace ``helloworld.factories.request_factory`` with the Python
dotted name to the request factory you want to use. Here's some
sample code that implements a minimal request factory:
.. code-block:: python
from webob import Request
from repoze.bfg.interfaces import IRequest
class MyRequest(Request):
implements(IRequest)
def request_factory():
return MyRequest
.. warning:: If you register an ``IRequestFactory`` utility in this
way, you *must* be sure that the factory returns an object that
implements *at least* the ``repoze.bfg.interfaces.IRequest``
interface. Otherwise all application view lookups will fail (they
will all return a 404 response code). Likewise, if you want to be
able to use method-related interfaces such as ``IGETRequest``,
``IPOSTRequest``, etc. in your view declarations, the callable
returned by the factory must also do the same introspection of the
environ that the default request factory does and decorate the
returned object to implement one of these interfaces based on the
``HTTP_METHOD`` present in the environ. Note that the above
example does not do this, so lookups for method-related interfaces
will fail.
Changing the response factory
-----------------------------
You may change the class used as the "response factory" from within
the :mod:`repoze.bfg` ``chameleon_zpt``, ``chameleon_genshi``,
``chameleon_text`` (the ``render_template_to_response`` function used
within each) and other various places where a Response object is
constructed by :mod:`repoze.bfg`. The default "response factory" is
the class ``webob.Response``. You may change it by placing the
following ZCML in your ``configure.zcml`` file.
.. code-block:: xml
:linenos:
<utility provides="repoze.bfg.interfaces.IResponseFactory"
component="helloworld.factories.response_factory"/>
Replace ``helloworld.factories.response_factory`` with the Python
dotted name to the response factory you want to use. Here's some
sample code that implements a minimal response factory:
.. code-block:: python
from webob import Response
class MyResponse(Response):
pass
def response_factory():
return MyResponse
Unlike a request factory, a response factory does not need to return
an object that implements any particular interface; it simply needs
have a ``status`` attribute, a ``headerlist`` attribute, and and
``app_iter`` attribute.
Changing the Not Found View
---------------------------
When :mod:`repoze.bfg` can't map a URL to view code, it invokes a
notfound :term:`view`. The view it invokes can be customized by
placing something like the following ZCML in your ``configure.zcml``
file.
.. code-block:: xml
:linenos:
<utility provides="repoze.bfg.interfaces.INotFoundView"
component="helloworld.views.notfound_view"/>
Replace ``helloworld.views.notfound_view`` with the Python dotted name
to the notfound view you want to use. Here's some sample code that
implements a minimal NotFound view:
.. code-block:: python
from webob.exc import HTTPNotFound
def notfound_view(context, request):
return HTTPNotFound()
.. note:: When a NotFound view is invoked, it is passed a request.
The ``environ`` attribute of the request is the WSGI environment.
Within the WSGI environ will be a key named ``repoze.bfg.message``
that has a value explaining why the not found error was raised.
This error will be different when the ``debug_notfound``
environment setting is true than it is when it is false.
Changing the Forbidden View
---------------------------
When :mod:`repoze.bfg` can't authorize execution of a view based on
the authorization policy in use, it invokes a "forbidden view". The
default forbidden response has a 401 status code and is very plain,
but it can be overridden as necessary by placing something like the
following ZCML in your ``configure.zcml`` file.
.. code-block:: xml
:linenos:
<utility provides="repoze.bfg.interfaces.IForbiddenView"
component="helloworld.views.forbidden_view"/>
Replace ``helloworld.factories.forbidden_app_factory`` with the Python
dotted name to the forbidden view you want to use. Like any other
view, the forbidden view must accept two parameters: ``context`` and
``request`` . The ``context`` is the context found by the router when
the view invocation was denied. The ``request`` is the current
:term:`request` representing the denied action. Here's some sample
code that implements a minimal forbidden view:
.. code-block:: python
from repoze.bfg.chameleon_zpt import render_template_to_response
def forbidden_response_factory(context, request):
return render_template_to_response('templates/login_form.pt')
.. note:: When an forbidden view is invoked, it is passed
the request as the second argument. An attribute of the request is
``environ``, which is the WSGI environment. Within the WSGI
environ will be a key named ``repoze.bfg.message`` that has a value
explaining why the current view invocation was forbidden. This
error will be different when the ``debug_authorization``
environment setting is true than it is when it is false.
.. warning:: the default forbidden view sends a response with a ``401
Unauthorized`` status code for backwards compatibility reasons.
You can influence the status code of Forbidden responses by using
an alterate forbidden view. For example, it would make sense to
return a response with a ``403 Forbidden`` status code.
Changing the Default Routes Context Factory
-------------------------------------------
The default Routes "context factory" (the object used to create
context objects when you use ``<route..>`` statements in your ZCML) is
``repoze.bfg.urldispatch.DefaultRoutesContext``. You may change the
class used as the Routes "context factory" by placing the following
ZCML in your ``configure.zcml`` file.
.. code-block:: xml
:linenos:
<utility provides="repoze.bfg.interfaces.IRoutesContextFactory"
component="helloworld.factories.routes_context_factory"/>
Replace ``helloworld.factories.routes_context_factory`` with the
Python dotted name to the context factory you want to use. Here's
some sample code that implements a minimal context factory:
.. code-block:: python
class RoutesContextFactory(object):
def __init__(self, **kw):
self.__dict__.update(kw)
|
