core/homeassistant/util/template.py

114 lines
3.2 KiB
Python

"""
homeassistant.util.template
~~~~~~~~~~~~~~~~~~~~~~~~~~~
Template utility methods for rendering strings with HA data.
"""
# pylint: disable=too-few-public-methods
import json
import logging
import jinja2
from jinja2.sandbox import ImmutableSandboxedEnvironment
from homeassistant.const import STATE_UNKNOWN
from homeassistant.exceptions import TemplateError
_LOGGER = logging.getLogger(__name__)
_SENTINEL = object()
def render_with_possible_json_value(hass, template, value,
error_value=_SENTINEL):
""" Renders template with value exposed.
If valid JSON will expose value_json too. """
variables = {
'value': value
}
try:
variables['value_json'] = json.loads(value)
except ValueError:
pass
try:
return render(hass, template, variables)
except TemplateError:
_LOGGER.exception('Error parsing value')
return value if error_value is _SENTINEL else error_value
def render(hass, template, variables=None, **kwargs):
""" Render given template. """
if variables is not None:
kwargs.update(variables)
try:
return ENV.from_string(template, {
'states': AllStates(hass),
'is_state': hass.states.is_state,
'is_state_attr': hass.states.is_state_attr
}).render(kwargs).strip()
except jinja2.TemplateError as err:
raise TemplateError(err)
class AllStates(object):
""" Class to expose all HA states as attributes. """
def __init__(self, hass):
self._hass = hass
def __getattr__(self, name):
return DomainStates(self._hass, name)
def __iter__(self):
return iter(sorted(self._hass.states.all(),
key=lambda state: state.entity_id))
def __call__(self, entity_id):
state = self._hass.states.get(entity_id)
return STATE_UNKNOWN if state is None else state.state
class DomainStates(object):
""" Class to expose a specific HA domain as attributes. """
def __init__(self, hass, domain):
self._hass = hass
self._domain = domain
def __getattr__(self, name):
return self._hass.states.get('{}.{}'.format(self._domain, name))
def __iter__(self):
return iter(sorted(
(state for state in self._hass.states.all()
if state.domain == self._domain),
key=lambda state: state.entity_id))
def forgiving_round(value, precision=0):
""" Rounding method that accepts strings. """
try:
value = round(float(value), precision)
return int(value) if precision == 0 else value
except ValueError:
# If value can't be converted to float
return value
def multiply(value, amount):
""" Converts to float and multiplies value. """
try:
return float(value) * amount
except ValueError:
# If value can't be converted to float
return value
class TemplateEnvironment(ImmutableSandboxedEnvironment):
""" Home Assistant template environment. """
def is_safe_callable(self, obj):
return isinstance(obj, AllStates) or super().is_safe_callable(obj)
ENV = TemplateEnvironment()
ENV.filters['round'] = forgiving_round
ENV.filters['multiply'] = multiply