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import xml.etree.ElementTree as et
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from django.db import models
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from boards.models import KeyPair
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TAG_MODEL = 'model'
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TAG_REQUEST = 'request'
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TAG_ID = 'id'
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TYPE_GET = 'get'
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TYPE_LIST = 'list'
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ATTR_VERSION = 'version'
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ATTR_TYPE = 'type'
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ATTR_NAME = 'name'
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ATTR_KEY = 'key'
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ATTR_KEY_TYPE = 'type'
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ATTR_LOCAL_ID = 'local-id'
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class GlobalIdManager(models.Manager):
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def global_id_exists(self, global_id):
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"""
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Checks if the same global id already exists in the system.
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"""
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return self.filter(key=global_id.key,
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key_type=global_id.key_type,
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local_id=global_id.local_id).exists()
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class GlobalId(models.Model):
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"""
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Global model ID and cache.
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Key, key type and local ID make a single global identificator of the model.
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Content is an XML cache of the model that can be passed along between nodes
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without manual serialization each time.
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"""
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class Meta:
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app_label = 'boards'
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objects = GlobalIdManager()
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def __init__(self, *args, **kwargs):
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models.Model.__init__(self, *args, **kwargs)
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if 'key' in kwargs and 'key_type' in kwargs and 'local_id' in kwargs:
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self.key = kwargs['key']
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self.key_type = kwargs['key_type']
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self.local_id = kwargs['local_id']
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key = models.TextField()
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key_type = models.TextField()
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local_id = models.IntegerField()
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content = models.TextField(blank=True, null=True)
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def __str__(self):
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return '%s::%s::%d' % (self.key_type, self.key, self.local_id)
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def to_xml_element(self, element: et.Element):
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"""
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Exports global id to an XML element.
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"""
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element.set(ATTR_KEY, self.key)
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element.set(ATTR_KEY_TYPE, self.key_type)
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element.set(ATTR_LOCAL_ID, str(self.local_id))
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@staticmethod
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def from_xml_element(element: et.Element):
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"""
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Parses XML id tag and gets global id from it.
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Arguments:
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element -- the XML 'id' element
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Returns:
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global_id -- id itself
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exists -- True if the global id was taken from database, False if it
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did not exist and was created.
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"""
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try:
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return GlobalId.objects.get(key=element.get(ATTR_KEY),
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key_type=element.get(ATTR_KEY_TYPE),
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local_id=int(element.get(
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ATTR_LOCAL_ID))), True
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except GlobalId.DoesNotExist:
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return GlobalId(key=element.get(ATTR_KEY),
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key_type=element.get(ATTR_KEY_TYPE),
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local_id=int(element.get(ATTR_LOCAL_ID))), False
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def is_local(self):
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"""Checks fo the ID is local model's"""
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return KeyPair.objects.filter(
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key_type=self.key_type, public_key=self.key).exists()
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def clear_cache(self):
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"""
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Removes content cache and signatures.
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"""
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self.content = None
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self.save()
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self.signature_set.all().delete()
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class Signature(models.Model):
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class Meta:
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app_label = 'boards'
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def __init__(self, *args, **kwargs):
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models.Model.__init__(self, *args, **kwargs)
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if 'key' in kwargs and 'key_type' in kwargs and 'signature' in kwargs:
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self.key_type = kwargs['key_type']
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self.key = kwargs['key']
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self.signature = kwargs['signature']
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key_type = models.TextField()
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key = models.TextField()
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signature = models.TextField()
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global_id = models.ForeignKey('GlobalId', on_delete=models.CASCADE)
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