Collection management (#520)

* Tech spec

* Refactored Cassanda knowledge graph for single table

* Collection management, librarian services to manage metadata and collection deletion

trustgraph-cli/trustgraph/cli/list_collections.py

@@ -0,0 +1,85 @@
+"""
+List collections for a user
+"""
+
+import argparse
+import os
+import tabulate
+from trustgraph.api import Api
+import json
+
+default_url = os.getenv("TRUSTGRAPH_URL", 'http://localhost:8088/')
+default_user = "trustgraph"
+
+def list_collections(url, user, tag_filter):
+
+    api = Api(url).collection()
+
+    collections = api.list_collections(user=user, tag_filter=tag_filter)
+
+    if len(collections) == 0:
+        print("No collections.")
+        return
+
+    table = []
+    for collection in collections:
+        table.append([
+            collection.collection,
+            collection.name,
+            collection.description,
+            ", ".join(collection.tags),
+            collection.created_at,
+            collection.updated_at
+        ])
+
+    headers = ["Collection", "Name", "Description", "Tags", "Created", "Updated"]
+
+    print(tabulate.tabulate(
+        table,
+        headers=headers,
+        tablefmt="pretty",
+        stralign="left",
+        maxcolwidths=[20, 30, 50, 30, 19, 19],
+    ))
+
+def main():
+
+    parser = argparse.ArgumentParser(
+        prog='tg-list-collections',
+        description=__doc__,
+    )
+
+    parser.add_argument(
+        '-u', '--api-url',
+        default=default_url,
+        help=f'API URL (default: {default_url})',
+    )
+
+    parser.add_argument(
+        '-U', '--user',
+        default=default_user,
+        help=f'User ID (default: {default_user})'
+    )
+
+    parser.add_argument(
+        '-t', '--tag-filter',
+        action='append',
+        help='Filter by tags (can be specified multiple times)'
+    )
+
+    args = parser.parse_args()
+
+    try:
+
+        list_collections(
+            url = args.api_url,
+            user = args.user,
+            tag_filter = args.tag_filter
+        )
+
+    except Exception as e:
+
+        print("Exception:", e, flush=True)
+
+if __name__ == "__main__":
+    main()