#!/usr/bin/env python
# -*- coding: utf-8 -*-
###############################################################################
# Copyright 2013 Kitware Inc.
#
# Licensed under the Apache License, Version 2.0 ( the "License" );
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
###############################################################################
import importlib
from . import camelcase
from girder import logger
# We want the models to essentially be singletons, so we keep this centralized
# cache of instantiated models that have been lazy-loaded.
_modelInstances = {}
def _loadModel(model, module, plugin):
global _modelInstances
className = camelcase(model)
try:
imported = importlib.import_module(module)
except ImportError:
logger.exception('Could not load model "{}".'.format(module))
raise
try:
constructor = getattr(imported, className)
except AttributeError: # pragma: no cover
raise Exception('Incorrect model class name "{}" for model "{}".'
.format(className, module))
_modelInstances[plugin][model] = constructor()
[docs]def clearModels():
"""
Force reloading of all models by clearing the singleton cache. This is
used by the test suite to ensure that indices are built properly
at startup.
"""
global _modelInstances
_modelInstances = {}
[docs]class ModelImporter(object):
"""
Any class that wants to have convenient model importing semantics
should extend/mixin this class.
"""
@staticmethod
[docs] def model(model, plugin='_core'):
"""
Call this to get the instance of the specified model. It will be
lazy-instantiated.
:param model: The name of the model to get. This is the module
name, e.g. "folder". The class name must be the
upper-camelcased version of that module name, e.g.
"Folder".
:type model: string
:param plugin: If the model you wish to load is a model within a plugin,
set this to the name of the plugin containing the model.
:returns: The instantiated model, which is a singleton.
"""
global _modelInstances
if plugin not in _modelInstances:
_modelInstances[plugin] = {}
if model not in _modelInstances[plugin]:
if plugin == '_core':
module = 'girder.models.{}'.format(model)
else:
module = 'girder.plugins.{}.models.{}'.format(plugin, model)
_loadModel(model, module, plugin)
return _modelInstances[plugin][model]
@staticmethod
[docs] def registerModel(model, instance, plugin='_core'):
"""
Use this method to manually register a model singleton instead of
having it automatically discovered.
:param model: The model name.
:type model: str
:param plugin: If a plugin model, pass the canonical plugin name.
:type plugin: str
:param instance: The model singleton instance.
:type instance: subclass of Model
"""
_modelInstances[plugin][model] = instance