views: add signposting link to landing+download response headers

invenio_app_rdm/records_ui/views/decorators.py

@@ -11,7 +11,7 @@
 
 from functools import wraps
 
-from flask import g, redirect, request, url_for
+from flask import g, make_response, redirect, request, url_for
 from invenio_communities.communities.resources.serializer import (
     UICommunityJSONSerializer,
 )
@@ -21,6 +21,8 @@
 from invenio_records_resources.services.errors import PermissionDeniedError
 from sqlalchemy.orm.exc import NoResultFound
 
+from invenio_app_rdm.urls import record_url_for
+
 
 def service():
     """Get the record service."""
@@ -103,11 +105,7 @@ def pass_is_preview(f):
 
     @wraps(f)
     def view(**kwargs):
-        preview = request.args.get("preview")
-        is_preview = False
-        if preview == "1":
-            is_preview = True
-        kwargs["is_preview"] = is_preview
+        kwargs["is_preview"] = request.args.get("preview") == "1"
         return f(**kwargs)
 
     return view
@@ -334,7 +332,6 @@ def view(**kwargs):
             pid_value = kwargs.get("pid_value")
             files = draft_files_service().list_files(id_=pid_value, identity=g.identity)
             kwargs["draft_files"] = files
-
         except PermissionDeniedError:
             # this is handled here because we don't want a 404 on the landing
             # page when a user is allowed to read the metadata but not the
@@ -365,3 +362,22 @@ def view(**kwargs):
         return f(**kwargs)
 
     return view
+
+
+def add_signposting(f):
+    """Add signposting link to view's response headers."""
+
+    @wraps(f)
+    def view(*args, **kwargs):
+        response = make_response(f(*args, **kwargs))
+
+        # Relies on other decorators having operated before it
+        pid_value = kwargs["pid_value"]
+        signposting_link = record_url_for(_app="api", pid_value=pid_value)
+
+        response.headers["Link"] = (
+            f'<{signposting_link}> ; rel="linkset" ; type="application/linkset+json"'  # fmt: skip
+        )
+        return response
+
+    return view

invenio_app_rdm/records_ui/views/records.py

@@ -39,6 +39,7 @@
 
 from ..utils import get_external_resources
 from .decorators import (
+    add_signposting,
     pass_file_item,
     pass_file_metadata,
     pass_include_deleted,
@@ -139,6 +140,7 @@ def open(self):
 @pass_record_or_draft(expand=True)
 @pass_record_files
 @pass_record_media_files
+@add_signposting
 def record_detail(
     pid_value, record, files, media_files, is_preview=False, include_deleted=False
 ):
@@ -300,6 +302,7 @@ def record_file_preview(
 
 @pass_is_preview
 @pass_file_item(is_media=False)
+@add_signposting
 def record_file_download(pid_value, file_item=None, is_preview=False, **kwargs):
     """Download a file from a record."""
     download = bool(request.args.get("download"))

invenio_app_rdm/urls.py

@@ -0,0 +1,62 @@
+# -*- coding: utf-8 -*-
+#
+# Copyright (C) 2023 Northwestern University.
+#
+# This file is lifted from Invenio-RDM-Records .
+#
+# Invenio-RDM-Records is free software; you can redistribute it and/or modify
+# it under the terms of the MIT License; see LICENSE file for more details.
+
+"""Convenient URL generation.
+
+InvenioRDM poses challenges to url generation that Flask's url_for cannot handle out
+of the gate.
+
+- InvenioRDM is actually 2 applications mounted on different url_prefixes:
+  `url_for` in the API application isn't aware of the UI application endpoints
+- The endpoint names are relatively hidden / spread out and APP_RDM_ROUTES is usually
+  the interface to name them.
+- Need to be able to generate urls outside of request context without thinking about it,
+
+This module contains minimal methods to generate URLs correctly without much
+engineering. Over time, it can be made more abstract, complex and powerful and even
+extracted into its own package to solve url generation across InvenioRDM once and for
+all.
+
+Design decisions:
+
+- Generated urls are absolute for now
+"""
+
+from flask import current_app
+
+
+def record_url_for(_app="ui", pid_value=""):
+    """Return url for record route."""
+    assert _app in ["ui", "api"]
+
+    site_app = _app.upper()
+    url_prefix = current_app.config.get(f"SITE_{site_app}_URL", "")
+
+    # We use [] so that this fails and brings to attention the configuration
+    # problem if APP_RDM_ROUTES.record_detail is missing
+    url_path = current_app.config["APP_RDM_ROUTES"]["record_detail"].replace(
+        "<pid_value>", pid_value
+    )
+
+    return "/".join(p.strip("/") for p in [url_prefix, url_path])
+
+
+def download_url_for(pid_value="", filename=""):
+    """Return url for download route."""
+    url_prefix = current_app.config.get(f"SITE_UI_URL", "")
+
+    # We use [] so that this fails and brings to attention the configuration
+    # problem if APP_RDM_ROUTES.record_file_download is missing
+    url_path = (
+        current_app.config["APP_RDM_ROUTES"]["record_file_download"]
+        .replace("<pid_value>", pid_value)
+        .replace("<path:filename>", filename)
+    )
+
+    return "/".join(p.strip("/") for p in [url_prefix, url_path])

tests/ui/conftest.py

@@ -8,6 +8,8 @@
 
 """Pytest fixtures and plugins for the UI application."""
 
+from io import BytesIO
+
 import pytest
 from flask_webpackext.manifest import (
     JinjaManifest,
@@ -68,3 +70,35 @@ def record(running_app, minimal_record):
     s = current_rdm_records.records_service
     draft = s.create(system_identity, minimal_record)
     return s.publish(system_identity, draft.id)
+
+
+@pytest.fixture()
+def record_with_file(running_app, minimal_record):
+    """Create and publish a record with file."""
+    minimal_record["files"] = {"enabled": True}
+
+    record_service = current_rdm_records.records_service
+    file_service = record_service.draft_files
+
+    draft = record_service.create(system_identity, minimal_record)
+    file_to_initialise = [
+        {
+            "key": "article.txt",
+            "checksum": "md5:c785060c866796cc2a1708c997154c8e",
+            "size": 17,  # 2kB
+            "metadata": {
+                "description": "Published article PDF.",
+            },
+        }
+    ]
+    file_service.init_files(system_identity, draft.id, file_to_initialise)
+    content = BytesIO(b"test file content")
+    file_service.set_file_content(
+        system_identity,
+        draft.id,
+        file_to_initialise[0]["key"],
+        content,
+        content.getbuffer().nbytes,
+    )
+    file_service.commit_file(system_identity, draft.id, "article.txt")
+    return record_service.publish(system_identity, draft.id)

tests/ui/test_signposting_ui.py

@@ -0,0 +1,33 @@
+# -*- coding: utf-8 -*-
+#
+# Copyright (C) 2023 Northwestern University.
+#
+# Invenio-App-RDM is free software; you can redistribute it and/or modify
+# it under the terms of the MIT License; see LICENSE file for more details.
+
+"""Test Signposting.
+
+See https://signposting.org/FAIR/#level2 for more information on Signposting
+"""
+
+
+def test_link_in_landing_page_response_headers(running_app, client, record):
+    res = client.head(f"/records/{record.id}")
+
+    assert (
+        res.headers["Link"]
+        == f'<https://127.0.0.1:5000/api/records/{record.id}> ; rel="linkset" ; type="application/linkset+json"'  # noqa
+    )
+
+
+def test_link_in_content_resource_response_headers(
+    running_app, client, record_with_file
+):
+    filename = "article.txt"
+
+    res = client.head(f"/records/{record_with_file.id}/files/{filename}")
+
+    assert (
+        res.headers["Link"]
+        == f'<https://127.0.0.1:5000/api/records/{record_with_file.id}> ; rel="linkset" ; type="application/linkset+json"'  # noqa
+    )