[XXX ‘copy answer from forum’ means reusing text from http://groups.google.com/group/google-appengine/browse_frm/thread/c9476925f5f66ec6 and http://groups.google.com/group/google-appengine/browse_frm/thread/d791ce17e2716147/eb078f8cfe8426e0 and http://groups.google.com/group/google-appengine/browse_frm/thread/f48cf6099973aef5/c28cd6934dd72457 ]
There are enough template languages out there. You can use your preferred template language if you want. [explain how to use a template language]
CubicWeb does not define its own templating language as this was not our goal. Based on our experience, we realized that we could gain productivity by letting designers use design tools and developpers develop without the use of the templating language as an intermediary that could not be anyway efficient for both parties. Python is the templating language that we use in CubicWeb, but again, it does not prevent you from using a templating language.
The reason template languages are not used in this book is that experience has proved us that using pure python was less cumbersome.
Python is an Object Oriented Programming language and as such it already provides a consistent and strong architecture and syntax a templating language would not reach.
When doing development, you need a real language and template languages are not real languages.
Using Python instead of a template langage for describing the user interface makes it to maintain with real functions/classes/contexts without the need of learning a new dialect. By using Python, we use standard OOP techniques and this is a key factor in a robust application.
LGPL means that if you redistribute your application, you need to redistribute the changes you made to CubicWeb under the LGPL licence.
Publishing a web site has nothing to do with redistributing source code. A fair amount of companies use modified LGPL code for internal use. And someone could publish a CubicWeb component under a BSD licence for others to plug into a LGPL framework without any problem. The only thing we are trying to prevent here is someone taking the framework and packaging it as closed source to his own clients.
It is constantly evolving, piece by piece. The framework has evolved since 2001 and data has been migrated from one schema to the other ever since. There is a well-defined way to handle data and schema migration.
It may remind you of SQL but it is higher level than SQL, more like SPARQL. Except that SPARQL did not exist when we started the project. With version 3.4, CubicWeb has support for SPARQL.
That RQL language is what is going to make a difference with django- like frameworks for several reasons.
[CubicWeb uses jQuery and adds a thin layer on top of that]
This is an example of how it works in our framework:
class Version(EntityType):
"""a version is defining the content of a particular project's
release"""
# definition of attributes is voluntarily missing
permissions = {'read': ('managers', 'users', 'guests',),
'update': ('managers', 'logilab', 'owners',),
'delete': ('managers', ),
'add': ('managers', 'logilab',
ERQLExpression('X version_of PROJ, U in_group G, '
'PROJ require_permission P, '
'P name "add_version", P require_group G'),)}
The above means that permission to read a Version is granted to any user that is part of one of the groups ‘managers’, ‘users’, ‘guests’. The ‘add’ permission is granted to users in group ‘managers’ or ‘logilab’ and to users in group G, if G is linked by a permission entity named “add_version” to the version’s project.
class version_of(RelationType):
"""link a version to its project. A version is necessarily linked
to one and only one project. """
# some lines voluntarily missing
permissions = {'read': ('managers', 'users', 'guests',),
'delete': ('managers', ),
'add': ('managers', 'logilab',
RRQLExpression('O require_permission P, P name "add_version", '
'U in_group G, P require_group G'),) }
You can find additional information in the section security.
[XXX what does the second example means in addition to the first one?]
While modifying the description of an entity, you get an error message in the instance Error while publishing ... for Rest text and plain text. The server returns a traceback like as follows
2008-10-06 15:05:08 - (cubicweb.rest) ERROR: error while publishing ReST text
Traceback (most recent call last):
File "/home/user/src/blogdemo/cubicweb/common/rest.py", line 217, in rest_publish
File "/usr/lib/python2.5/codecs.py", line 817, in open
file = __builtin__.open(filename, mode, buffering)
TypeError: __init__() takes at most 3 arguments (4 given)
This can be fixed by applying the patch described in : http://code.google.com/p/googleappengine/issues/detail?id=48
Hooks are executed around (actually before or after) events. The most common events are data creation, update and deletion. They permit additional constraint checking (those not expressible at the schema level), pre and post computations depending on data movements.
As such, they are a vital part of the framework.
Other kinds of hooks, called Operations, are available for execution just before commit.
An HTML template cannot contain code, hence it is only about static content. A component is made of code and operations that apply on a well defined context (request, result set). It enables much more dynamic views.
AppRsetObject instances are selected on a request and a result set. AppObject instances are directly selected by id.
It depends on what has been modified in the schema.
This allows to bypass authentication for your site. In the all-in-one.conf file of your instance, define the anonymous user as follows
# login of the CubicWeb user account to use for anonymous user (if you want to
# allow anonymous)
anonymous-user=anon
# password of the CubicWeb user account matching login
anonymous-password=anon
You also must ensure that this anon user is a registered user of the DB backend. If not, you can create through the administation interface of your instance by adding a user with the role guests. This could be the admin account (for development purposes, of course).
Note
While creating a new instance, you can decide to allow access to anonymous user, which will automatically execute what is decribed above.
There are two ways of changing the logo.
The easiest way to use a different logo is to replace the existing logo.png in myapp/data by your prefered icon and refresh. By default all instance will look for a logo.png to be rendered in the logo section.
In your cube directory, you can specify which file to use for the logo. This is configurable in mycube/data/external_resources:
LOGO = DATADIR/path/to/mylogo.gif
where DATADIR is mycube/data.
Your instance’s sources are defined in /etc/cubicweb.d/myapp/sources. Configuring an LDAP source is about declaring that source in your instance configuration file such as:
[ldapuser]
adapter=ldapuser
# ldap host
host=myhost
# base DN to lookup for usres
user-base-dn=ou=People,dc=mydomain,dc=fr
# user search scope
user-scope=ONELEVEL
# classes of user
user-classes=top,posixAccount
# attribute used as login on authentication
user-login-attr=uid
# name of a group in which ldap users will be by default
user-default-group=users
# map from ldap user attributes to cubicweb attributes
user-attrs-map=gecos:email,uid:login
Any change applied to configuration file requires to restart your instance.
You just need to put the appropriate context manager around view/component selection (one standard place in in vreg.py):
def possible_objects(self, registry, *args, **kwargs):
"""return an iterator on possible objects in a registry for this result set
actions returned are classes, not instances
"""
from cubicweb.selectors import traced_selection
with traced_selection():
for vobjects in self.registry(registry).values():
try:
yield self.select(vobjects, *args, **kwargs)
except NoSelectableObject:
continue
Don’t forget the ‘from __future__ import with_statement’ at the module top-level.
This will yield additional WARNINGs, like this:
2009-01-09 16:43:52 - (cubicweb.selectors) WARNING: selector one_line_rset returned 0 for <class 'cubicweb.web.views.basecomponents.WFHistoryVComponent'>
If your schema has an attribute of type Date or Datetime, you might want to format it. First, you should define your preferred format using the site configuration panel http://appurl/view?vid=systempropertiesform and then set ui.date and/or ui.datetime. Then in the view code, use:
self.format_date(entity.date_attribute)
If you have PostgreSQL set up to accept kerberos authentication, you can set the db-host, db-name and db-user parameters in the sources configuration file while leaving the password blank. It should be enough for your instance to connect to postgresql with a kerberos ticket.
The following script aims at loading data within a script assuming pyro-nsd is running and your instance is configured with pyro-server=yes, otherwise you would not be able to use dbapi.
from cubicweb import dbapi
cnx = dbapi.connection(database='instance-id', user='admin', password='admin')
cur = cnx.cursor()
for name in ('Personal', 'Professional', 'Computers'):
cur.execute('INSERT Blog B: B name %s', name)
cnx.commit()
If you take a look at your instance schema and click on “display detailed view of metadata” you will see that there is a Euser entity in there. That’s the one that is modeling users. The thing that corresponds to a UserProperty is a relationship between your entity and the Euser entity. As in:
class TodoItem(EntityType):
text = String()
todo_by = SubjectRelation('Euser')
[XXX check that cw handle users better by mapping Google Accounts to local Euser entities automatically]
If you want to reset the admin password for myinstance, do:
$ cubicweb-ctl reset-admin-pwd myinstance
You need to generate a new encrypted password:
$ python
>>> from cubicweb.server.utils import crypt_password
>>> crypt_password('joepass')
'qHO8282QN5Utg'
>>>
and paste it in the database:
$ psql mydb
mydb=> update cw_cwuser set cw_upassword='qHO8282QN5Utg' where cw_login='joe';
UPDATE 1
You are probably getting errors such as
remove {'PR': 'Project', 'C': 'CWUser'} from solutions since your_user has no read access to cost
This is because you have to put your user in the “users” group. The user has to be in both groups.