From 5955868b9a611de736af29c76f5fdfef94d1c774 Mon Sep 17 00:00:00 2001
From: Alan Orth <alan.orth@gmail.com>
Date: Mon, 2 Mar 2020 11:06:27 +0200
Subject: [PATCH] dspace_statistics_api/app.py: Use UUID

DSpace 6+ uses a UUID for item identifiers instead of an integer so
we need to adapt our PostgreSQL queries to use those. Note that we
can no longer sort results in the "all items" endpoint by ID. Also,
we need to use parameterized psycopg2 queries instead of strings to
support queries with UUIDs properly. To use the Python UUID objects
elsewhere in the code we need to make sure that we cast them to str.
---
 dspace_statistics_api/app.py | 20 +++++++++++++-------
 1 file changed, 13 insertions(+), 7 deletions(-)

diff --git a/dspace_statistics_api/app.py b/dspace_statistics_api/app.py
index 1c8d8a8..e29f0e6 100644
--- a/dspace_statistics_api/app.py
+++ b/dspace_statistics_api/app.py
@@ -27,9 +27,9 @@ class AllItemsResource:
                 cursor.execute("SELECT COUNT(id) FROM items")
                 pages = round(cursor.fetchone()[0] / limit)
 
-                # get statistics, ordered by id, and use limit and offset to page through results
+                # get statistics and use limit and offset to page through results
                 cursor.execute(
-                    "SELECT id, views, downloads FROM items ORDER BY id ASC LIMIT {} OFFSET {}".format(
+                    "SELECT id, views, downloads FROM items LIMIT {} OFFSET {}".format(
                         limit, offset
                     )
                 )
@@ -41,7 +41,7 @@ class AllItemsResource:
                 for item in cursor:
                     statistics.append(
                         {
-                            "id": item["id"],
+                            "id": str(item["id"]),
                             "views": item["views"],
                             "downloads": item["downloads"],
                         }
@@ -61,26 +61,32 @@ class ItemResource:
     def on_get(self, req, resp, item_id):
         """Handles GET requests"""
 
+        import psycopg2.extras
+
+        # Adapt Python’s uuid.UUID type to PostgreSQL’s uuid
+        # See: https://www.psycopg.org/docs/extras.html
+        psycopg2.extras.register_uuid()
+
         with DatabaseManager() as db:
             db.set_session(readonly=True)
 
             with db.cursor() as cursor:
                 cursor = db.cursor()
                 cursor.execute(
-                    "SELECT views, downloads FROM items WHERE id={}".format(item_id)
+                    "SELECT views, downloads FROM items WHERE id=%s", [str(item_id)]
                 )
                 if cursor.rowcount == 0:
                     raise falcon.HTTPNotFound(
                         title="Item not found",
                         description='The item with id "{}" was not found.'.format(
-                            item_id
+                            str(item_id)
                         ),
                     )
                 else:
                     results = cursor.fetchone()
 
                     statistics = {
-                        "id": item_id,
+                        "id": str(item_id),
                         "views": results["views"],
                         "downloads": results["downloads"],
                     }
@@ -91,6 +97,6 @@ class ItemResource:
 api = application = falcon.API()
 api.add_route("/", RootResource())
 api.add_route("/items", AllItemsResource())
-api.add_route("/item/{item_id:int}", ItemResource())
+api.add_route("/item/{item_id:uuid}", ItemResource())
 
 # vim: set sw=4 ts=4 expandtab: