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dspace-statistics-api
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Refactor `/items` POST handler to use a before hook 

This allows us to do the dirty work of parsing, validating, and
setting local variables from the POST parameters outside of the
on_post function. We then share the parameters via the req.context
object. Functionally it is the same, but readability is better
and it's a neat trick that I could use elsewhere.

See: https://falcon.readthedocs.io/en/stable/user/faq.html#how-can-i-pass-data-from-a-hook-to-a-responder-and-between-hooks
This commit is contained in:
Alan Orth 2020-09-26 18:37:14 +03:00
parent 3ceb9a6eb0
commit 5a53b57b3b
Signed by: alanorth
GPG Key ID: 0FB860CC9C45B1B9
2 changed files with 87 additions and 64 deletions
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82
dspace_statistics_api/app.py
View File

@ -1,6 +1,7 @@
import falcon
from .database import DatabaseManager
from .util import validate_items_post_parameters
class RootResource:
@ -55,74 +56,29 @@ class AllItemsResource:
resp.media = message
@falcon.before(validate_items_post_parameters)
def on_post(self, req, resp):
"""Handles POST requests"""
import json
from .items import get_views
from .items import get_downloads
from .util import is_valid_date
# Only attempt to read the POSTed request if its length is not 0 (or
# rather, in the Python sense, if length is not a False-y value).
if req.content_length:
doc = json.load(req.bounded_stream)
else:
raise falcon.HTTPBadRequest(
title="Invalid request", description=f"Request body is empty."
)
# Parse date parameters from request body (will raise an HTTPBadRequest
# from is_valid_date() if any parameters are invalid)
req_dateFrom = (
doc["dateFrom"]
if "dateFrom" in doc and is_valid_date(doc["dateFrom"])
else None
)
req_dateTo = (
doc["dateTo"] if "dateTo" in doc and is_valid_date(doc["dateTo"]) else None
)
# Build the Solr date string, ie: [* TO *]
if req_dateFrom and req_dateTo:
solr_date_string = f"[{req_dateFrom} TO {req_dateTo}]"
elif not req_dateFrom and req_dateTo:
solr_date_string = f"[* TO {req_dateTo}]"
elif req_dateFrom and not req_dateTo:
solr_date_string = f"[{req_dateFrom} TO *]"
if req.context.dateFrom and req.context.dateTo:
solr_date_string = f"[{req.context.dateFrom} TO {req.context.dateTo}]"
elif not req.context.dateFrom and req.context.dateTo:
solr_date_string = f"[* TO {req.context.dateTo}]"
elif req.context.dateFrom and not req.context.dateTo:
solr_date_string = f"[{req.context.dateFrom} TO *]"
else:
solr_date_string = "[* TO *]"
# Parse the limit parameter from the POST request body
req_limit = doc["limit"] if "limit" in doc else 100
if not isinstance(req_limit, int) or req_limit < 0 or req_limit > 100:
raise falcon.HTTPBadRequest(
title="Invalid parameter",
description=f'The "limit" parameter is invalid. The value must be an integer between 0 and 100.',
)
# Parse the page parameter from the POST request body
req_page = doc["page"] if "page" in doc else 0
if not isinstance(req_page, int) or req_page < 0:
raise falcon.HTTPBadRequest(
title="Invalid parameter",
description=f'The "page" parameter is invalid. The value must be at least 0.',
)
# Parse the list of items from the POST request body
req_items = doc["items"] if "items" in doc else list()
if not isinstance(req_items, list) or len(req_items) == 0:
raise falcon.HTTPBadRequest(
title="Invalid parameter",
description=f'The "items" parameter is invalid. The value must be a comma-separated list of item UUIDs.',
)
# Helper variables to make working with pages/items/results easier and
# to make the code easier to understand
number_of_items: int = len(req_items)
pages: int = int(number_of_items / req_limit)
first_item: int = req_page * req_limit
last_item: int = first_item + req_limit
number_of_items: int = len(req.context.items)
pages: int = int(number_of_items / req.context.limit)
first_item: int = req.context.page * req.context.limit
last_item: int = first_item + req.context.limit
# Get a subset of the POSTed items based on our limit. Note that Python
# list slicing and indexing are both zero based, but the first and last
# items in a slice can be confusing. See this ASCII diagram:
@ -133,12 +89,12 @@ class AllItemsResource:
# Slice position: 0 1 2 3 4 5 6
# Index position: 0 1 2 3 4 5
#
# So if we have a list req_items with 240 items:
# So if we have a list items with 240 items:
#
# 1st set: req_items[0:100] would give items at indexes 0 to 99
# 2nd set: req_items[100:200] would give items at indexes 100 to 199
# 3rd set: req_items[200:300] would give items at indexes 200 to 239
items_subset: list = req_items[first_item:last_item]
# 1st set: items[0:100] would give items at indexes 0 to 99
# 2nd set: items[100:200] would give items at indexes 100 to 199
# 3rd set: items[200:300] would give items at indexes 200 to 239
items_subset: list = req.context.items[first_item:last_item]
views: dict = get_views(solr_date_string, items_subset)
downloads: dict = get_downloads(solr_date_string, items_subset)
@ -152,9 +108,9 @@ class AllItemsResource:
statistics.append({"id": k, "views": v, "downloads": downloads[k]})
message = {
"currentPage": req_page,
"currentPage": req.context.page,
"totalPages": pages,
"limit": req_limit,
"limit": req.context.limit,
"statistics": statistics,
}

69
dspace_statistics_api/util.py
View File

@ -1,3 +1,6 @@
import falcon
def get_statistics_shards():
"""Enumerate the cores in Solr to determine if statistics have been sharded into
yearly shards by DSpace's stats-util or not (for example: statistics-2018).
@ -55,7 +58,6 @@ def get_statistics_shards():
def is_valid_date(date):
import datetime
import falcon
try:
# Solr date format is: 2020-01-01T00:00:00Z
@ -68,3 +70,68 @@ def is_valid_date(date):
title="Invalid parameter",
description=f"Invalid date format: {date}. The value must be in format: 2020-01-01T00:00:00Z.",
)
def validate_items_post_parameters(req, resp, resource, params):
"""Check the POSTed request parameters for the `/items` endpoint.
Meant to be used as a `before` hook.
"""
import json
# Only attempt to read the POSTed request if its length is not 0 (or
# rather, in the Python sense, if length is not a False-y value).
if req.content_length:
doc = json.load(req.bounded_stream)
else:
raise falcon.HTTPBadRequest(
title="Invalid request", description=f"Request body is empty."
)
# Parse date parameters from request body (will raise an HTTPBadRequest
# from is_valid_date() if any parameters are invalid)
if "dateFrom" in doc and is_valid_date(doc["dateFrom"]):
req.context.dateFrom = doc["dateFrom"]
else:
req.context.dateFrom = None
if "dateTo" in doc and is_valid_date(doc["dateTo"]):
req.context.dateTo = doc["dateTo"]
else:
req.context.dateTo = None
# Parse the limit parameter from the POST request body
if "limit" in doc:
if isinstance(doc["limit"], int) and 0 < doc["limit"] < 100:
req.context.limit = doc["limit"]
else:
raise falcon.HTTPBadRequest(
title="Invalid parameter",
description=f'The "limit" parameter is invalid. The value must be an integer between 0 and 100.',
)
else:
req.context.limit = 100
# Parse the page parameter from the POST request body
if "page" in doc:
if isinstance(doc["page"], int) and doc["page"] >= 0:
req.context.page = doc["page"]
else:
raise falcon.HTTPBadRequest(
title="Invalid parameter",
description=f'The "page" parameter is invalid. The value must be at least 0.',
)
else:
req.context.page = 0
# Parse the list of items from the POST request body
if "items" in doc:
if isinstance(doc["items"], list) and len(doc["items"]) > 0:
req.context.items = doc["items"]
else:
raise falcon.HTTPBadRequest(
title="Invalid parameter",
description=f'The "items" parameter is invalid. The value must be a comma-separated list of item UUIDs.',
)
else:
req.context.items = list()