Added getter_callback to Characteristic

CHANGELOG.md

@@ -8,6 +8,10 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/).
 
 ## [Unreleased]
 
+### Added
+
+- Added `getter_callback` to Characteristics. [#90](https://github.com/ikalchev/HAP-python/pull/90)
+
 ### Changed
 - Improved documentation for version `2.0.0`. [#114](https://github.com/ikalchev/HAP-python/pull/114)
 

pyhap/accessory_driver.py

@@ -381,7 +381,7 @@ def get_characteristics(self, char_ids):
             rep = {HAP_REPR_AID: aid, HAP_REPR_IID: iid}
             char = self.accessory.get_characteristic(aid, iid)
             try:
-                rep[HAP_REPR_VALUE] = char.value
+                rep[HAP_REPR_VALUE] = char.get_value()
                 rep[HAP_REPR_STATUS] = CHAR_STAT_OK
             except CharacteristicError:
                 logger.error("Error getting value for characteristic %s.", id)
@@ -442,7 +442,7 @@ def set_characteristics(self, chars_query, client_addr):
                 # TODO: status needs to be based on success of set_value
                 char.client_update_value(cq[HAP_REPR_VALUE])
                 if "r" in cq:
-                    response[HAP_REPR_VALUE] = char.value
+                    response[HAP_REPR_VALUE] = char.get_value()
 
             chars_response.append(response)
         return {HAP_REPR_CHARS: chars_response}

pyhap/characteristic.py

@@ -79,7 +79,7 @@ class Characteristic:
     """
 
     __slots__ = ('display_name', 'type_id', 'properties', 'broker',
-                 'setter_callback', 'value')
+                 'value', 'getter_callback', 'setter_callback')
 
     def __init__(self, display_name, type_id, properties):
         """Initialise with the given properties.
@@ -98,8 +98,9 @@ def __init__(self, display_name, type_id, properties):
         self.type_id = type_id
         self.properties = properties
         self.broker = None
-        self.setter_callback = None
         self.value = self._get_default_value()
+        self.getter_callback = None
+        self.setter_callback = None
 
     def __repr__(self):
         """Return the representation of the characteristic."""
@@ -114,6 +115,15 @@ def _get_default_value(self):
             value = HAP_FORMAT_DEFAULTS[self.properties[PROP_FORMAT]]
             return self.to_valid_value(value)
 
+    def get_value(self):
+        """
+        This is to allow for calling `getter_callback`
+        :return: Current Characteristic Value
+        """
+        if self.getter_callback:
+            self.value = self.to_valid_value(value=self.getter_callback())
+        return self.value
+
     def to_valid_value(self, value):
         """Perform validation and conversion to valid value"""
         if self.properties.get(PROP_VALID_VALUES):
@@ -168,6 +178,12 @@ def set_value(self, value, should_notify=True):
         If not set_value will be aborted and an error message will be
         displayed.
 
+        `Characteristic.setter_callback`
+        You may also define a `setter_callback` on the `Characteristic`.
+        This will be called with the value being set as the arg.
+
+        .. seealso:: Characteristic.value
+
         :param value: The value to assign as this Characteristic's value.
         :type value: Depends on properties["Format"]
 
@@ -183,11 +199,10 @@ def set_value(self, value, should_notify=True):
 
     def client_update_value(self, value):
         """Called from broker for value change in Home app.
-
         Change self.value to value and call callback.
         """
         logger.debug('client_update_value: %s to %s',
-                      self.display_name, value)
+                     self.display_name, value)
         self.value = value
         self.notify()
         if self.setter_callback:
@@ -217,14 +232,15 @@ def to_HAP(self):
             HAP_REPR_FORMAT: self.properties[PROP_FORMAT],
         }
 
+        value = self.get_value()
         if self.properties[PROP_FORMAT] in HAP_FORMAT_NUMERICS:
             hap_rep.update({k: self.properties[k] for k in
                             self.properties.keys() & PROP_NUMERIC})
         elif self.properties[PROP_FORMAT] == HAP_FORMAT_STRING:
-            if len(self.value) > 64:
-                hap_rep[HAP_REPR_MAX_LEN] = min(len(self.value), 256)
+            if len(value) > 64:
+                hap_rep[HAP_REPR_MAX_LEN] = min(len(value), 256)
         if HAP_PERMISSION_READ in self.properties[PROP_PERMISSIONS]:
-            hap_rep[HAP_REPR_VALUE] = self.value
+            hap_rep[HAP_REPR_VALUE] = value
 
         return hap_rep
 

pyhap/service.py

@@ -50,7 +50,7 @@ def get_characteristic(self, name):
         raise ValueError('Characteristic not found')
 
     def configure_char(self, char_name, properties=None, valid_values=None,
-                       value=None, setter_callback=None):
+                       value=None, setter_callback=None, getter_callback=None):
         """Helper method to return fully configured characteristic."""
         char = self.get_characteristic(char_name)
         if properties or valid_values:
@@ -59,6 +59,8 @@ def configure_char(self, char_name, properties=None, valid_values=None,
             char.set_value(value, should_notify=False)
         if setter_callback:
             char.setter_callback = setter_callback
+        if getter_callback:
+            char.getter_callback = getter_callback
         return char
 
     def to_HAP(self):