Source code for girder.utility.model_importer

#!/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]