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
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import importlib
import six

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):
    className = camelcase(model)

    try:
        imported = importlib.import_module(module)
    except ImportError:
        logger.exception('Could not load model "%s".' % module)
        raise

    try:
        constructor = getattr(imported, className)
    except AttributeError:
        raise Exception('Incorrect model class name "%s" for model "%s".' % (
            className, module))

    _modelInstances[plugin][model] = constructor()


[docs]def reinitializeAll(): """ Force all models to reconnect/rebuild indices (needed for testing). .. deprecated """ for pluginModels in list(six.viewvalues(_modelInstances)): for model in list(six.viewvalues(pluginModels)): model.reconnect()
[docs]class ModelImporter(object): """ Any class that wants to have convenient model importing semantics should extend/mixin this class. """
[docs] @staticmethod def model(model, plugin=None): """ 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. """ if plugin is None: plugin = '_core' if plugin not in _modelInstances: _modelInstances[plugin] = {} if model not in _modelInstances[plugin]: if plugin == '_core': module = 'girder.models.%s' % model else: raise Exception('Model "%s" is not registered in plugin "%s"' % (model, plugin)) _loadModel(model, module, plugin) return _modelInstances[plugin][model]
[docs] @staticmethod 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 """ if plugin not in _modelInstances: _modelInstances[plugin] = {} _modelInstances[plugin][model] = instance
@staticmethod def unregisterModel(model, plugin='_core'): del _modelInstances[plugin][model]