mirror of https://gitlab.crans.org/bde/nk20
142 lines
4.8 KiB
Python
142 lines
4.8 KiB
Python
import functools
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import json
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import operator
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from django.contrib.contenttypes.models import ContentType
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from django.core.exceptions import ValidationError
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from django.db import models
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from django.db.models import Q
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from django.utils.translation import gettext_lazy as _
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class InstancedPermission:
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def __init__(self, model, query, type, field):
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self.model = model
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self.query = query
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self.type = type
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self.field = field
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def applies(self, obj, permission_type, field_name=None):
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"""
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Returns True if the permission applies to
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the field `field_name` object `obj`
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"""
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if ContentType.objects.get_for_model(obj) != self.model:
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# The permission does not apply to the model
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return False
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if self.permission is None:
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if permission_type == self.type:
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if field_name is not None:
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return field_name == self.field
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else:
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return True
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else:
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return False
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elif obj in self.model.objects.get(self.query):
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return True
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else:
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return False
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def __repr__(self):
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if self.field:
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return _("Can {type} {model}.{field} in {permission}").format(type=self.type, model=self.model, field=self.field, permission=self.permission)
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else:
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return _("Can {type} {model} in {permission}").format(type=self.type, model=self.model, permission=self.permission)
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class Permission(models.Model):
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PERMISSION_TYPES = [
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('add', 'add'),
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('view', 'view'),
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('change', 'change'),
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('delete', 'delete')
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]
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model = models.ForeignKey(ContentType, on_delete=models.CASCADE, related_name='+')
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# A json encoded Q object with the following grammar
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# query -> [] | {} (the empty query representing all objects)
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# query -> ['AND', query, …]
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# -> ['OR', query, …]
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# -> ['NOT', query]
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# query -> {key: value, …}
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# key -> string
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# value -> int | string | bool | null
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# -> [parameter]
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#
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# Examples:
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# Q(is_admin=True) := {'is_admin': ['TYPE', 'bool', 'True']}
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# ~Q(is_admin=True) := ['NOT', {'is_admin': ['TYPE', 'bool', 'True']}]
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query = models.TextField()
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type = models.CharField(max_length=15, choices=PERMISSION_TYPES)
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field = models.CharField(max_length=255, blank=True)
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description = models.CharField(max_length=255, blank=True)
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class Meta:
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unique_together = ('model', 'query', 'type', 'field')
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def clean(self):
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if self.field and self.type not in {'view', 'change'}:
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raise ValidationError(_("Specifying field applies only to view and change permission types."))
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def save(self):
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self.full_clean()
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super().save()
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def _about(_self, _query, **kwargs):
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self = _self
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query = _query
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if len(query) == 0:
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# The query is either [] or {} and
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# applies to all objects of the model
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# to represent this we return None
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return None
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if isinstance(query, list):
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if query[0] == 'AND':
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return functools.reduce(operator.and_, [self._about(query, **kwargs) for query in query[1:]])
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elif query[0] == 'OR':
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return functools.reduce(operator.or_, [self._about(query, **kwargs) for query in query[1:]])
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elif query[0] == 'NOT':
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return ~self._about(query[1], **kwargs)
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elif isinstance(query, dict):
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q_kwargs = {}
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for key in query:
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value = query[key]
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if isinstance(value, list):
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# It is a parameter we query its primary key
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q_kwargs[key] = kwargs[value[0]].pk
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else:
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q_kwargs[key] = value
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return Q(**q_kwargs)
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else:
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# TODO: find a better way to crash here
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raise Exception("query {} is wrong".format(self.query))
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def about(self, **kwargs):
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"""
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Return an InstancedPermission with the parameters
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replaced by their values and the query interpreted
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"""
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query = json.loads(self.query)
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query = self._about(query, **kwargs)
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return InstancedPermission(self.model, query, self.type, self.field)
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def __str__(self):
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if self.field:
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return _("Can {type} {model}.{field} in {query}").format(type=self.type, model=self.model, field=self.field, query=self.query)
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else:
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return _("Can {type} {model} in {query}").format(type=self.type, model=self.model, query=self.query)
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class UserPermission(models.Model):
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user = models.ForeignKey('auth.User', on_delete=models.CASCADE)
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permission = models.ForeignKey(Permission, on_delete=models.CASCADE)
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