Source code for canlib.kvadblib.node

import ctypes as ct

from .attribute import Attribute
from .enums import AttributeOwner
from .exceptions import KvdNoAttribute, KvdWrongOwner
from .wrapper import dll


[docs]class Node(object): """Database Node""" def __init__(self, db, handle, name=None, comment=None): self._handle = handle self._db = db # used to lookup attribute definitions if name is not None: self.name = name if comment is not None: self.comment = comment def __eq__(self, other): if self.name != other.name: return False if self.comment != other.comment: return False return True def __ne__(self, other): return not self == other def __repr__(self): return "Node(name='{}, comment={}')".format(self.name, self.comment)
[docs] def attributes(self): """Return a generator over all message attributes.""" ah = None nah = ct.c_void_p() try: dll.kvaDbGetFirstNodeAttribute(self._handle, ct.byref(nah)) except KvdNoAttribute: return while nah.value is not None: ah, nah = nah, ct.c_void_p() yield Attribute(self, ah) try: dll.kvaDbGetNextAttribute(ah, ct.byref(nah)) except KvdNoAttribute: return
[docs] def delete_attribute(self, name): """Delete attribute from node.""" ah = ct.c_void_p() dll.kvaDbGetNodeAttributeByName(self._handle, name.encode('utf-8'), ct.byref(ah)) dll.kvaDbDeleteNodeAttribute(self._handle, ah)
[docs] def get_attribute_value(self, name): """Return attribute value If the attribute is not set on the message, we return the attribute definition default value. """ ah = ct.c_void_p() # Try and find attribute on node try: dll.kvaDbGetNodeAttributeByName(self._handle, name.encode('utf-8'), ct.byref(ah)) except KvdNoAttribute: # Lookup the attribute definition atr_def = self._db.get_attribute_definition_by_name(name) # only attributes with node as owner are valid, name is also # unique accross all attributes so it is enough to check this one # for owner if atr_def.owner != AttributeOwner.NODE: raise KvdWrongOwner() value = atr_def.definition.default else: attribute = Attribute(self._db, ah) value = attribute.value return value
[docs] def set_attribute_value(self, name, value): """Set value of attribute 'name' on node. If no attribute called 'name' is set on node, attach a node attribute from the database attribute definition first. """ ah = ct.c_void_p() # Try and find attribute on node try: dll.kvaDbGetNodeAttributeByName(self._handle, name.encode('utf-8'), ct.byref(ah)) except KvdNoAttribute: # If no attribute was found, lookup the attribute definition and # add a new attribute to the node attrib_def = self._db.get_attribute_definition_by_name(name) dll.kvaDbAddNodeAttribute(self._handle, attrib_def._handle, ct.byref(ah)) # Set the value in the node attribute attribute = Attribute(self._db, ah) attribute.value = value
@property def comment(self): """`str`: The node's comment""" buf = ct.create_string_buffer(255) dll.kvaDbGetNodeComment(self._handle, buf, ct.sizeof(buf)) return buf.value.decode('utf-8') @comment.setter def comment(self, value): dll.kvaDbSetNodeComment(self._handle, value.encode('utf-8')) @property def name(self): """`str`: The node's name""" buf = ct.create_string_buffer(255) dll.kvaDbGetNodeName(self._handle, buf, ct.sizeof(buf)) return buf.value.decode('utf-8') @name.setter def name(self, value): dll.kvaDbSetNodeName(self._handle, value.encode('utf-8'))