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notifications-api/app/v2/notifications/get_notifications.py

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from io import BytesIO
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from flask import current_app, jsonify, request, send_file, url_for
from app import api_user, authenticated_service
from app.dao import notifications_dao
from app.letters.utils import get_letter_pdf_and_metadata
from app.models import (
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LETTER_TYPE,
NOTIFICATION_PENDING_VIRUS_CHECK,
NOTIFICATION_TECHNICAL_FAILURE,
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NOTIFICATION_VIRUS_SCAN_FAILED,
)
from app.schema_validation import validate
from app.v2.errors import BadRequestError, PDFNotReadyError
from app.v2.notifications import v2_notification_blueprint
from app.v2.notifications.notification_schemas import (
get_notifications_request,
notification_by_id,
)
@v2_notification_blueprint.route("/<notification_id>", methods=['GET'])
def get_notification_by_id(notification_id):
_data = {"notification_id": notification_id}
validate(_data, notification_by_id)
notification = notifications_dao.get_notification_with_personalisation(
authenticated_service.id, notification_id, key_type=None
)
return jsonify(notification.serialize()), 200
@v2_notification_blueprint.route('/<notification_id>/pdf', methods=['GET'])
def get_pdf_for_notification(notification_id):
_data = {"notification_id": notification_id}
validate(_data, notification_by_id)
notification = notifications_dao.get_notification_by_id(
notification_id, authenticated_service.id, _raise=True
)
if notification.notification_type != LETTER_TYPE:
raise BadRequestError(message="Notification is not a letter")
if notification.status == NOTIFICATION_VIRUS_SCAN_FAILED:
raise BadRequestError(message='File did not pass the virus scan')
if notification.status == NOTIFICATION_TECHNICAL_FAILURE:
raise BadRequestError(message='PDF not available for letters in status {}'.format(notification.status))
if notification.status == NOTIFICATION_PENDING_VIRUS_CHECK:
raise PDFNotReadyError()
try:
pdf_data, metadata = get_letter_pdf_and_metadata(notification)
except Exception:
raise PDFNotReadyError()
return send_file(path_or_file=BytesIO(pdf_data), mimetype='application/pdf')
@v2_notification_blueprint.route("", methods=['GET'])
def get_notifications():
_data = request.args.to_dict(flat=False)
# flat=False makes everything a list, but we only ever allow one value for "older_than"
if 'older_than' in _data:
_data['older_than'] = _data['older_than'][0]
# and client reference
if 'reference' in _data:
_data['reference'] = _data['reference'][0]
if 'include_jobs' in _data:
_data['include_jobs'] = _data['include_jobs'][0]
data = validate(_data, get_notifications_request)
paginated_notifications = notifications_dao.get_notifications_for_service(
str(authenticated_service.id),
filter_dict=data,
key_type=api_user.key_type,
personalisation=True,
older_than=data.get('older_than'),
client_reference=data.get('reference'),
page_size=current_app.config.get('API_PAGE_SIZE'),
Set `count_pages` as False to stop running of redundant query This is a similar PR to https://github.com/alphagov/notifications-api/pull/2284. When using flask-sqlalchemy to get a `Pagination` object, by default it will run two queries 1. Get the page of results that you are asking for 2. If the number of results is equal to the page size, then it will issue a second query that will count the total number of results Getting the total number of results is only useful if - you need to show how many results there are - you need to know if there is a next page of results (flask-sqlalchemy uses the total to work out how many pages there are altogether, which may not be the most efficient way of working out if there is a next page or not but that is what it currently does). Looking at the `get_notifications` route, it does not use `paginated_notifications.total` or `paginated_notifications.has_next` and therefore we have no use for the second query to get the total number of results. We can stop this additional query by setting `count_pages=False` which will hopefully give us some performance improvements, in particular for services which send a lot of notifications. Flask sqlalchemy references: https://github.com/pallets/flask-sqlalchemy/blob/818c947b665206fe8edd8c1680b18ce83d3e4744/src/flask_sqlalchemy/__init__.py#L478 https://github.com/pallets/flask-sqlalchemy/blob/818c947b665206fe8edd8c1680b18ce83d3e4744/src/flask_sqlalchemy/__init__.py#L399 Note, I have checked the other uses of `get_notifications_for_service` and the other cases are currently using the total or next page so this approach is not something we can take with them.
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include_jobs=data.get('include_jobs'),
count_pages=False
)
def _build_links(notifications):
_links = {
'current': url_for(".get_notifications", _external=True, **data),
}
if len(notifications):
next_query_params = dict(data, older_than=notifications[-1].id)
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_links['next'] = url_for(".get_notifications", _external=True, **next_query_params)
return _links
return jsonify(
notifications=[notification.serialize() for notification in paginated_notifications.items],
links=_build_links(paginated_notifications.items)
), 200