core/homeassistant/components/template/template_entity.py

296 lines
9.3 KiB
Python

"""TemplateEntity utility class."""
import logging
from typing import Any, Callable, List, Optional, Union
import voluptuous as vol
from homeassistant.const import ATTR_ENTITY_ID
from homeassistant.core import EVENT_HOMEASSISTANT_START, CoreState, callback
from homeassistant.exceptions import TemplateError
import homeassistant.helpers.config_validation as cv
from homeassistant.helpers.entity import Entity
from homeassistant.helpers.event import (
Event,
TrackTemplate,
TrackTemplateResult,
async_track_template_result,
)
from homeassistant.helpers.template import Template, result_as_boolean
_LOGGER = logging.getLogger(__name__)
class _TemplateAttribute:
"""Attribute value linked to template result."""
def __init__(
self,
entity: Entity,
attribute: str,
template: Template,
validator: Callable[[Any], Any] = None,
on_update: Optional[Callable[[Any], None]] = None,
none_on_template_error: Optional[bool] = False,
):
"""Template attribute."""
self._entity = entity
self._attribute = attribute
self.template = template
self.validator = validator
self.on_update = on_update
self.async_update = None
self.none_on_template_error = none_on_template_error
@callback
def async_setup(self):
"""Config update path for the attribute."""
if self.on_update:
return
if not hasattr(self._entity, self._attribute):
raise AttributeError(f"Attribute '{self._attribute}' does not exist.")
self.on_update = self._default_update
@callback
def _default_update(self, result):
attr_result = None if isinstance(result, TemplateError) else result
setattr(self._entity, self._attribute, attr_result)
@callback
def handle_result(
self,
event: Optional[Event],
template: Template,
last_result: Union[str, None, TemplateError],
result: Union[str, TemplateError],
) -> None:
"""Handle a template result event callback."""
if isinstance(result, TemplateError):
_LOGGER.error(
"TemplateError('%s') "
"while processing template '%s' "
"for attribute '%s' in entity '%s'",
result,
self.template,
self._attribute,
self._entity.entity_id,
)
if self.none_on_template_error:
self._default_update(result)
else:
self.on_update(result)
return
if not self.validator:
self.on_update(result)
return
try:
validated = self.validator(result)
except vol.Invalid as ex:
_LOGGER.error(
"Error validating template result '%s' "
"from template '%s' "
"for attribute '%s' in entity %s "
"validation message '%s'",
result,
self.template,
self._attribute,
self._entity.entity_id,
ex.msg,
)
self.on_update(None)
return
self.on_update(validated)
return
class TemplateEntity(Entity):
"""Entity that uses templates to calculate attributes."""
def __init__(
self,
*,
availability_template=None,
icon_template=None,
entity_picture_template=None,
attribute_templates=None,
):
"""Template Entity."""
self._template_attrs = {}
self._async_update = None
self._attribute_templates = attribute_templates
self._attributes = {}
self._availability_template = availability_template
self._available = True
self._icon_template = icon_template
self._entity_picture_template = entity_picture_template
self._icon = None
self._entity_picture = None
self._self_ref_update_count = 0
@property
def should_poll(self):
"""No polling needed."""
return False
@callback
def _update_available(self, result):
if isinstance(result, TemplateError):
self._available = True
return
self._available = result_as_boolean(result)
@callback
def _update_state(self, result):
if self._availability_template:
return
self._available = not isinstance(result, TemplateError)
@property
def available(self) -> bool:
"""Return if the device is available."""
return self._available
@property
def icon(self):
"""Return the icon to use in the frontend, if any."""
return self._icon
@property
def entity_picture(self):
"""Return the entity_picture to use in the frontend, if any."""
return self._entity_picture
@property
def device_state_attributes(self):
"""Return the state attributes."""
return self._attributes
@callback
def _add_attribute_template(self, attribute_key, attribute_template):
"""Create a template tracker for the attribute."""
def _update_attribute(result):
attr_result = None if isinstance(result, TemplateError) else result
self._attributes[attribute_key] = attr_result
self.add_template_attribute(
attribute_key, attribute_template, None, _update_attribute
)
def add_template_attribute(
self,
attribute: str,
template: Template,
validator: Callable[[Any], Any] = None,
on_update: Optional[Callable[[Any], None]] = None,
none_on_template_error: bool = False,
) -> None:
"""
Call in the constructor to add a template linked to a attribute.
Parameters
----------
attribute
The name of the attribute to link to. This attribute must exist
unless a custom on_update method is supplied.
template
The template to calculate.
validator
Validator function to parse the result and ensure it's valid.
on_update
Called to store the template result rather than storing it
the supplied attribute. Passed the result of the validator, or None
if the template or validator resulted in an error.
"""
attribute = _TemplateAttribute(
self, attribute, template, validator, on_update, none_on_template_error
)
self._template_attrs.setdefault(template, [])
self._template_attrs[template].append(attribute)
@callback
def _handle_results(
self,
event: Optional[Event],
updates: List[TrackTemplateResult],
) -> None:
"""Call back the results to the attributes."""
if event:
self.async_set_context(event.context)
entity_id = event and event.data.get(ATTR_ENTITY_ID)
if entity_id and entity_id == self.entity_id:
self._self_ref_update_count += 1
else:
self._self_ref_update_count = 0
if self._self_ref_update_count > len(self._template_attrs):
for update in updates:
_LOGGER.warning(
"Template loop detected while processing event: %s, skipping template render for Template[%s]",
event,
update.template.template,
)
return
for update in updates:
for attr in self._template_attrs[update.template]:
attr.handle_result(
event, update.template, update.last_result, update.result
)
self.async_write_ha_state()
async def _async_template_startup(self, *_) -> None:
template_var_tups = []
for template, attributes in self._template_attrs.items():
template_var_tups.append(TrackTemplate(template, None))
for attribute in attributes:
attribute.async_setup()
result_info = async_track_template_result(
self.hass, template_var_tups, self._handle_results
)
self.async_on_remove(result_info.async_remove)
self._async_update = result_info.async_refresh
result_info.async_refresh()
async def async_added_to_hass(self) -> None:
"""Run when entity about to be added to hass."""
if self._availability_template is not None:
self.add_template_attribute(
"_available", self._availability_template, None, self._update_available
)
if self._attribute_templates is not None:
for key, value in self._attribute_templates.items():
self._add_attribute_template(key, value)
if self._icon_template is not None:
self.add_template_attribute(
"_icon", self._icon_template, vol.Or(cv.whitespace, cv.icon)
)
if self._entity_picture_template is not None:
self.add_template_attribute(
"_entity_picture", self._entity_picture_template
)
if self.hass.state == CoreState.running:
await self._async_template_startup()
return
self.hass.bus.async_listen_once(
EVENT_HOMEASSISTANT_START, self._async_template_startup
)
async def async_update(self) -> None:
"""Call for forced update."""
self._async_update()