Make encoding.serialize() more programmatical

Introduce `serializable_fields` to express which class attributes
to be serialized.

Get rid of OrderedDict. Just replacing it with regular dict.

Change-Id: I3f7639dab171d3d62e92d0d1bb6d7b071cf963ad

5 files changed, 22 insertions, 54 deletions

diff --git a/ironic_python_agent/agent.py b/ironic_python_agent/agent.py
index 39c8368c..7a75f0a3 100644
--- a/ironic_python_agent/agent.py
+++ b/ironic_python_agent/agent.py
@@ -27,7 +27,6 @@ from ironic_python_agent.extensions import base
 from ironic_python_agent import hardware
 from ironic_python_agent import ironic_api_client
 from ironic_python_agent.openstack.common import log
-from ironic_python_agent import utils
 
 
 def _time():
@@ -36,17 +35,12 @@ def _time():
 
 
 class IronicPythonAgentStatus(encoding.Serializable):
+    serializable_fields = ('started_at', 'version')
+
     def __init__(self, started_at, version):
         self.started_at = started_at
         self.version = version
 
-    def serialize(self):
-        """Turn the status into a dict."""
-        return utils.get_ordereddict([
-            ('started_at', self.started_at),
-            ('version', self.version),
-        ])
-
 
 class IronicPythonAgentHeartbeater(threading.Thread):
     # If we could wait at most N seconds between heartbeats (or in case of an
diff --git a/ironic_python_agent/encoding.py b/ironic_python_agent/encoding.py
index acf0cfed..bd521d3e 100644
--- a/ironic_python_agent/encoding.py
+++ b/ironic_python_agent/encoding.py
@@ -18,9 +18,11 @@ import uuid
 
 class Serializable(object):
     """Base class for things that can be serialized."""
+    serializable_fields = ()
+
     def serialize(self):
         """Turn this object into a dict."""
-        raise NotImplementedError()
+        return dict((f, getattr(self, f)) for f in self.serializable_fields)
 
 
 class RESTJSONEncoder(json.JSONEncoder):
diff --git a/ironic_python_agent/errors.py b/ironic_python_agent/errors.py
index 151d8cea..0cb9ad4a 100644
--- a/ironic_python_agent/errors.py
+++ b/ironic_python_agent/errors.py
@@ -13,7 +13,6 @@
 # limitations under the License.
 
 from ironic_python_agent import encoding
-from ironic_python_agent import utils
 
 
 class RESTError(Exception, encoding.Serializable):
@@ -21,15 +20,12 @@ class RESTError(Exception, encoding.Serializable):
     message = 'An error occurred'
     details = 'An unexpected error occurred. Please try back later.'
     status_code = 500
+    serializable_fields = ('type', 'code', 'message', 'details')
 
-    def serialize(self):
-        """Turn a RESTError into a dict."""
-        return utils.get_ordereddict([
-            ('type', self.__class__.__name__),
-            ('code', self.status_code),
-            ('message', self.message),
-            ('details', self.details),
-        ])
+    def __init__(self, *args, **kwargs):
+        super(RESTError, self).__init__(*args, **kwargs)
+        self.type = self.__class__.__name__
+        self.code = self.status_code
 
 
 class InvalidContentError(RESTError):
diff --git a/ironic_python_agent/extensions/base.py b/ironic_python_agent/extensions/base.py
index c9b351bd..3ef5c4ea 100644
--- a/ironic_python_agent/extensions/base.py
+++ b/ironic_python_agent/extensions/base.py
@@ -31,6 +31,9 @@ class AgentCommandStatus(object):
 
 
 class BaseCommandResult(encoding.Serializable):
+    serializable_fields = ('id', 'command_name', 'command_params',
+                           'command_status', 'command_error', 'command_result')
+
     def __init__(self, command_name, command_params):
         self.id = six.text_type(uuid.uuid4())
         self.command_name = command_name
@@ -39,16 +42,6 @@ class BaseCommandResult(encoding.Serializable):
         self.command_error = None
         self.command_result = None
 
-    def serialize(self):
-        return dict((
-            (u'id', self.id),
-            (u'command_name', self.command_name),
-            (u'command_params', self.command_params),
-            (u'command_status', self.command_status),
-            (u'command_error', self.command_error),
-            (u'command_result', self.command_result),
-        ))
-
     def is_done(self):
         return self.command_status != AgentCommandStatus.RUNNING
 
diff --git a/ironic_python_agent/hardware.py b/ironic_python_agent/hardware.py
index 8c466d65..b1165457 100644
--- a/ironic_python_agent/hardware.py
+++ b/ironic_python_agent/hardware.py
@@ -45,18 +45,17 @@ class HardwareType(object):
 
 
 class BlockDevice(encoding.Serializable):
+    serializable_fields = ('name', 'size')
+
     def __init__(self, name, size):
         self.name = name
         self.size = size
 
-    def serialize(self):
-        return utils.get_ordereddict([
-            ('name', self.name),
-            ('size', self.size),
-        ])
-
 
 class NetworkInterface(encoding.Serializable):
+    serializable_fields = ('name', 'mac_address', 'switch_port_descr',
+                           'switch_chassis_descr')
+
     def __init__(self, name, mac_addr):
         self.name = name
         self.mac_address = mac_addr
@@ -64,38 +63,22 @@ class NetworkInterface(encoding.Serializable):
         self.switch_port_descr = None
         self.switch_chassis_descr = None
 
-    def serialize(self):
-        return utils.get_ordereddict([
-            ('name', self.name),
-            ('mac_address', self.mac_address),
-            ('switch_port_descr', self.switch_port_descr),
-            ('switch_chassis_descr', self.switch_port_descr),
-        ])
-
 
 class CPU(encoding.Serializable):
+    serializable_fields = ('model_name', 'frequency', 'count')
+
     def __init__(self, model_name, frequency, count):
         self.model_name = model_name
         self.frequency = frequency
         self.count = count
 
-    def serialize(self):
-        return utils.get_ordereddict([
-            ('model_name', self.model_name),
-            ('frequency', self.frequency),
-            ('count', self.count),
-        ])
-
 
 class Memory(encoding.Serializable):
+    serializable_fields = ('total', )
+
     def __init__(self, total):
         self.total = total
 
-    def serialize(self):
-        return utils.get_ordereddict([
-            ('total', self.total),
-        ])
-
 
 @six.add_metaclass(abc.ABCMeta)
 class HardwareManager(object):