# Copyright 2015 Google 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 logging

from flask import current_app, Flask, redirect, url_for

def create_app(config, debug=False, testing=False, config_overrides=None):

app = Flask(__name__)

app.config.from_object(config)

app.debug = debug

app.testing = testing

if config_overrides:

app.config.update(config_overrides)

# Configure logging

if not app.testing:

logging.basicConfig(level=logging.INFO)

# Setup the data model.

with app.app_context():

model = get_model()

model.init_app(app)

# Register the Bookshelf CRUD blueprint.

from .crud import crud

app.register_blueprint(crud, url_prefix='/books')

# Add a default root route.

@app.route("/")

def index():

return redirect(url_for('crud.list'))

# Add an error handler. This is useful for debugging the live application,

# however, you should disable the output of the exception for production

# applications.

@app.errorhandler(500)

def server_error(e):

return """

An internal error occurred: <pre>{}</pre>

See logs for full stacktrace.

""".format(e), 500

return app

def get_model():

model_backend = current_app.config['DATA_BACKEND']

if model_backend == 'cloudsql':

from . import model_cloudsql

model = model_cloudsql

elif model_backend == 'datastore':

from . import model_datastore

model = model_datastore

elif model_backend == 'mongodb':

from . import model_mongodb

model = model_mongodb

else:

raise ValueError(

"No appropriate databackend configured. "

"Please specify datastore, cloudsql, or mongodb")

return model