Optimize model loader do load method

Author: Reskov

src/gino/loader.py

@@ -206,25 +206,52 @@ class ModelLoader(Loader):
  def __init__(self, model, *columns, **extras):
  self.model = model
  self._distinct = None
+
+ self._columns = None
+ self._prop_column_map = None
+
  if columns:
- self.columns = [_get_column(model, name) for name in columns]
+ self.columns = tuple(_get_column(model, name) for name in columns)
  else:
  self.columns = model
  self.extras = dict((key, self.get(value)) for key, value in extras.items())
  self.on_clause = None
 
+ @property
+ def columns(self):
+ return self._columns
+
+ @columns.setter
+ def columns(self, value):
+ self._columns = value
+ self._prop_column_map = {
+ self.model._column_name_map.invert_get(c.name): c for c in self.columns
+ }
+
  def _do_load(self, row, none_as_none):
  # none_as_none indicates that in the case of every column of the object is
  # None, whether a None or empty instance of the model should be returned.
- values = dict((c.name, row[c]) for c in self.columns if c in row)
- if none_as_none and all((v is None) for v in values.values()):
+ all_is_none = none_as_none
+
+ values = {}
+
+ for prop_name, column in self._prop_column_map.items():
+ try:
+ row_value = row[column]
+ except KeyError:
+ # model is partially loaded skip
+ continue
+
+ values[prop_name] = row_value
+ all_is_none &= row_value is None
+
+ if all_is_none:
  return None
+
  rv = self.model()
- for c in self.columns:
- if c in row:
- # noinspection PyProtectedMember
- instance_key = self.model._column_name_map.invert_get(c.name)
- rv.__values__[instance_key] = row[c]
+ # no need to update, model just created
+ rv.__values__ = values
+
  return rv
 
  def do_load(self, row, context):
@@ -300,7 +327,7 @@ def load(self, *columns, **extras):
  """
 
  if columns:
- self.columns = [_get_column(self.model, name) for name in columns]
+ self.columns = tuple(_get_column(self.model, name) for name in columns)
 
  self.extras.update((key, self.get(value)) for key, value in extras.items())
  return self