Code


Version 13 (modified by Chris Long <indirecthit@…>, 8 years ago) (diff)

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TOC(inline)?

Introduction

What are Row Level Permissions?

An example of row level permissions would be: "User A has read-access to article 234" or "User D has read, write access to article 234".

Why do we need this?

An example of where this would be useful is a forum or message board. With the current permission system, a user is capable of editing all the posts or unable to edit any posts. After implementing a row level permission, it can be modified so a user is capable of editing only their own personal posts.

Todo

This is a slightly incomplete list, as of this writing my todo list is unavailable, I'll modify this when I have access to it

  • Adding row level permission editing to admin interface - Started. I have created an application that modifies row level permissions and will be adding this to the administration interface.
  • Adding checking of row level permissions (so they actually do something)

Using Row Level Permissions

Basic Idea

There are a few things you need to know about row level permissions before working with them:

  • Row level permissions use the permissions table to determine an objects possible permissions, you need to create permissions in the permissions table before using them in row level permissions.
  • Row level permissions can be negative, this is determined by an attribute called "negative".
  • The order of checking permissions will work in the following order: User Row Level Permission -> User Model Level Permission -> Group Row Level Permission -> Group Model Level Permission. The checking will stop either at the first positive or negative, and if no permission is found will return a negative.

Enabling Row Level Permissions

Enabling row level permissions is done by using the Meta class, you enable row level permissions by setting the "row_level_permissions" attribute to true. By default, row level permissions are assumed to be disabled.

Example: To enable row level permissions for the mineral model, the model would look like:

class Mineral(models.Model):
    name = models.CharField(maxlength=150)
    hardness = models.PositiveSmallIntegerField()
    
    class Admin:
        pass
    
    class Meta:
        unique_together = (('name', 'hardness'),)
        row_level_permissions = True
  
    def __str__(self):
        return self.name

Accessing Row Level Permissions from a Model

The relation name for row level permissions from a model is "row_level_permissions", this will return all row level permissions related to the instance of the object. For example, this will return all row level permissions related to the object quartz:

...
rlp_list = quartz.row_level_permissions.all()
...

Accessing the Owner and Model of a Row Level Permission

To return the owner of a row level permission use the attribute "owner". For example:

...
user = row_level_permission.owner
...

To return the instance of a row level permission use the attribte "type". For example:

...
object = row_level_permission.type
...

Developer's note: This will most likely change as I'm not too sure "type" accurately describes what it represents. I will update this page when I make the change.

Creating a Row Level Permission

There are two helper methods to create row level permissions. These can be accessed by using the Row Level Permissions manager (e.g. RowLevelPermission.objects)

The first is create_row_level_permission:

def create_row_level_permission(self, object_instance, owner_instance, permission, negative=False):
   ...

The permission param can either be the codename of the permission or a permission instance. The negative param is optional and will default to false. You must pass an instance of the object and owner to this method. Developer's Note: I will probably add in another option to allow the permission to be an id as well.

The second is create_default_row_permissions:

def create_default_row_level_permissions(self, object_instance, owner_instance, change=True, delete=True, negChange=False, negDel=False):
   ...

This will set up a row level permission with the default permissions set up for an object. The default permissions are: add, change and delete. An example of it's use is:

...
RowLevelPermissions.objects.create_default_row_level_permissions(quartz, user, delete=False)
...

Checking Permissions

This will be integrated into the GenericAuthorization SoC project. More info to come.

Implementation Notes

Please see RowLevelPermissionsDeveloper for more information on how row level permissions are implemented.

Download

Row Level Permissions are currently hosted in a branch on Django SVN. Please use: svn co http://code.djangoproject.com/svn/django/branches/per-object-permissions to download the current code. As of July 13, the subversion repository has not been updated. I will be doing this tomorrow once I finish testing my latest changes and additions. Please ignore the attached files as these are old versions of the row level permissions.