A node to represents an HTML element with attributes.
An HTML element without content is called an empty node. It has a start tag but neither a content nor an end tag. Compared to the parent class BaseNode, this class adds 2 members:
For example, it can deal with elements like:
Create a new empty node.
def __init__(self, parent: str | None, identifier: str, tag: str, attributes: dict=dict()):
"""Create a new empty node.
:param parent: (str) Parent identifier
:param identifier: (str) This node identifier
:param tag: (str) The element tag. Converted in lower case.
:param attributes: (dict) key=(str) value=(str or None)
:raises: NodeInvalidIdentifierError:
:raises: NodeTagError:
:raises: TypeError:
"""
super(BaseTagNode, self).__init__(parent, identifier)
tag = str(tag)
self.__tag = tag.lower()
self._attributes = dict()
if isinstance(attributes, dict) is False:
raise TypeError('Expected a dict for the attributes argument of BaseTagNode().')
for key in attributes:
value = attributes[key]
self.add_attribute(key, value)
Return the HTML tag.
@property
def tag(self) -> str:
"""Return the HTML tag. """
return self.__tag
Raises NodeAttributeError if key is not a valid attribute.
def check_attribute(self, key) -> str:
"""Raises NodeAttributeError if key is not a valid attribute.
:param key: (any) An attribute
:raises: NodeAttributeError: The attribute can't be assigned to this element.
:raises: NodeAttributeError: if given key can't be converted to string
:return: key (str) valid key
"""
try:
key = str(key)
key = key.lower()
except Exception:
raise NodeAttributeError(key)
if key not in HTML_GLOBAL_ATTR and key.startswith('data-') is False and (key not in HTML_VISIBLE_ATTR) and (key not in HTML_TAG_ATTR.keys()) and (key not in ARIA_TAG_ATTR.keys()):
raise NodeAttributeError(key)
return key
Return the list of attribute keys.
def get_attribute_keys(self) -> list:
"""Return the list of attribute keys. """
return [k for k in self._attributes.keys()]
Set a property to the node. Delete the existing one, if any.
def set_attribute(self, key: str, value) -> str:
"""Set a property to the node. Delete the existing one, if any.
:param key: Key property
:param value: (str or list)
:raises: NodeAttributeError: The attribute can't be assigned to this element.
:raises: NodeAttributeError: if given key can't be converted to string
:return: key (str) valid assigned key
"""
key = self.check_attribute(key)
if isinstance(value, (list, tuple)) is True:
value = ' '.join(value)
self._attributes[key] = value
return key
Add a property to the node. Append the value if existing.
def add_attribute(self, key: str, value) -> str:
"""Add a property to the node. Append the value if existing.
:param key: (str) Key property
:param value:
:raises: NodeAttributeError: The attribute can't be assigned to this element.
:raises: NodeAttributeError: if given key can't be converted to string
:return: key (str) valid assigned key
"""
if key not in self._attributes:
self.set_attribute(key, value)
elif self._attributes[key] is not None:
self._attributes[key] += ' ' + value
else:
self._attributes[key] = value
return key
Return the attribute value if the node has this attribute.
def get_attribute_value(self, key: str):
"""Return the attribute value if the node has this attribute.
:param key: (str) Attribute key
:return: (str | None) Value or None if the attribute does not exist or has no value
"""
if key in self._attributes:
return self._attributes[key]
return None
Return true if the node has the attribute.
def has_attribute(self, key: str) -> bool:
"""Return true if the node has the attribute.
:param key: (str) Attribute key
:return: (bool)
"""
return key in self._attributes
Remove the attribute to the node.
def remove_attribute(self, key: str) -> None:
"""Remove the attribute to the node.
:param key: (str) Attribute key
"""
if key in self._attributes:
del self._attributes[key]
Remove the value of an attribute of the node.
def remove_attribute_value(self, key: str, value: str) -> None:
"""Remove the value of an attribute of the node.
:param key: (str) Attribute key
:param value: (str) Attribute value
"""
if key in self._attributes:
values = self._attributes[key].split(' ')
if value in values:
values.remove(value)
if len(values) == 0:
del self._attributes[key]
else:
self.set_attribute(key, ' '.join(values))
Return the number of attributes.
def nb_attributes(self) -> int:
"""Return the number of attributes. """
return len(self._attributes)
Override. Serialize the node into HTML.
def serialize(self, nbs: int=4) -> str:
"""Override. Serialize the node into HTML.
:param nbs: (int) Number of spaces for the indentation
:return: (str)
"""
indent = ' ' * nbs
html = indent + '<' + self.__tag
for key in self._attributes:
html += ' '
html += key
value = self._attributes[key]
if value is not None:
html += '="'
html += value
html += '"'
html += ' />\n'
return html