Checking Permissions

How to check permission in python code.

When generating user interface elements you might want to check that the current logged in principal actually can access a view to which a link refers. You need to do two things: 1 get the view, 2 check permissions on that view. This is how you do it:

from zope.component import getMultiAdapter
from zope.security import canAccess

def canAccessView(obj, view_name):
    # obj - is the object you want view
    # view_name - is the grok.View/AddForm/EditForm you want to access
    view = getMultiAdapter((obj, self.request), name=view_name)
    # check if you can access the __call__ method which is equal
    # to being allowed to access this view.
    return canAccess(view, '__call__')

If you want to check if the current logged in principal has a specific permission on a specific object or view you can do so by means of the checkPermission method. It is available through zope.security and in a view through self.request.interaction. Note that Grok doesn’t allow a simplified way of setting object level permissions. The grok.requires statement is only applicable to views.

from zope.security import checkPermission
def justChecking(context):
    # context - the object or view you are checking permissions on
    user_allowed = checkPermission(PERMISSION_NAME, context)

class MyView(grok.View):
    def update(self):
        i = self.request.interaction
        # checking permission on currently viewed object (self.context)
        user_allowed = i.checkPermission(PERMISSION_NAME, self.context)