Implement for OPDS2 and add tests.

src/palace/manager/feed/serializer/opds.py

@@ -55,6 +55,15 @@
 }
 
 
+def is_sort_link(link: Link) -> bool:
+    """A until method that determines if the specified link is a sort link"""
+    return (
+        hasattr(link, "facetGroup")
+        and link.facetGroup
+        == FacetConstants.GROUP_DISPLAY_TITLES[FacetConstants.ORDER_FACET_GROUP_NAME]
+    )
+
+
 class OPDS1Serializer(SerializerInterface[etree._Element], OPDSFeed):
     """An OPDS 1.2 Atom feed serializer"""
 
@@ -110,22 +119,16 @@ def serialize_feed(
             serialized.append(breadcrumbs)
 
         for link in feed.facet_links:
-            if self.is_sort_link(link):
+            if is_sort_link(link):
                 serialized.append(self._serialize_sort_link(link))
+                # TODO once the clients are no longer relying on facet based sorting
+                # an "else" should be introduced here since we only need to provide one style of sorting links
             serialized.append(self._serialize_feed_entry("link", link))
+            # TODO end else here
 
         etree.indent(serialized)
         return self.to_string(serialized)
 
-    def is_sort_link(self, link) -> bool:
-        return (
-            hasattr(link, "facetGroup")
-            and link.facetGroup
-            == FacetConstants.GROUP_DISPLAY_TITLES[
-                FacetConstants.ORDER_FACET_GROUP_NAME
-            ]
-        )
-
     def _serialize_feed_metadata(self, metadata: FeedMetadata) -> list[etree._Element]:
         tags = []
         # Compulsory title
@@ -406,7 +409,9 @@ def content_type(self) -> str:
         return OPDSFeed.ACQUISITION_FEED_TYPE
 
     def _serialize_sort_link(self, link: Link) -> etree._Element:
-        sort_link = Link(href=link.href, title=link.title, rel=AtomFeed.PALACE_REL_NS)
+        sort_link = Link(
+            href=link.href, title=link.title, rel=AtomFeed.PALACE_REL_NS + "sort"
+        )
         if link.get("activeFacet", False):
             sort_link.add_attributes(dict(activeSort="true"))
         return self._serialize_feed_entry("link", sort_link)

src/palace/manager/feed/serializer/opds2.py

@@ -3,6 +3,7 @@
 from typing import Any
 
 from palace.manager.feed.serializer.base import SerializerInterface
+from palace.manager.feed.serializer.opds import is_sort_link
 from palace.manager.feed.types import (
     Acquisition,
     Author,
@@ -12,7 +13,7 @@
     WorkEntryData,
 )
 from palace.manager.sqlalchemy.model.contributor import Contributor
-from palace.manager.util.opds_writer import OPDSMessage
+from palace.manager.util.opds_writer import AtomFeed, OPDSMessage
 
 ALLOWED_ROLES = [
     "translator",
@@ -31,6 +32,9 @@
     if name.lower() in ALLOWED_ROLES
 }
 
+PALACE_REL_SORT = AtomFeed.PALACE_REL_SORT
+PALACE_PROPERTIES_ACTIVE_SORT = AtomFeed.PALACE_PROPS_NS + "active-sort"
+
 
 class OPDS2Serializer(SerializerInterface[dict[str, Any]]):
     CONTENT_TYPE = "application/opds+json"
@@ -191,15 +195,24 @@ def _serialize_feed_links(self, feed: FeedData) -> dict[str, Any]:
 
         facet_links: dict[str, Any] = defaultdict(lambda: {"metadata": {}, "links": []})
         for link in feed.facet_links:
-            group = getattr(link, "facetGroup", None)
-            if group:
-                facet_links[group]["links"].append(self._serialize_link(link))
-                facet_links[group]["metadata"]["title"] = group
+            if is_sort_link(link):
+                link_data["links"].append(self._serialize_sort_link(link))
+            else:
+                group = getattr(link, "facetGroup", None)
+                if group:
+                    facet_links[group]["links"].append(self._serialize_link(link))
+                    facet_links[group]["metadata"]["title"] = group
         for _, facets in facet_links.items():
             link_data["facets"].append(facets)
 
         return link_data
 
+    def _serialize_sort_link(self, link: Link):
+        sort_link = {"href": link.href, "title": link.title, "rel": PALACE_REL_SORT}
+        if link.get("activeFacet", False):
+            sort_link["properties"] = {PALACE_PROPERTIES_ACTIVE_SORT: "true"}
+        return sort_link
+
     def _serialize_contributor(self, author: Author) -> dict[str, Any]:
         result: dict[str, Any] = {"name": author.name}
         if author.sort_name:

src/palace/manager/util/opds_writer.py

@@ -42,8 +42,12 @@ class AtomFeed:
     BIB_SCHEMA_NS = "http://bib.schema.org/"
 
     LCP_NS = "http://readium.org/lcp-specs/ns"
+
     PALACE_REL_NS = "http://palaceproject.io/terms/rel/"
     PALACE_PROPS_NS = "http://palaceproject.io/terms/properties/"
+
+    PALACE_REL_SORT = PALACE_REL_NS + "sort"
+
     nsmap = {
         None: ATOM_NS,
         "app": APP_NS,

tests/manager/feed/test_opds2_serializer.py

@@ -1,6 +1,10 @@
 import json
 
-from palace.manager.feed.serializer.opds2 import OPDS2Serializer
+from palace.manager.feed.serializer.opds2 import (
+    PALACE_PROPERTIES_ACTIVE_SORT,
+    PALACE_REL_SORT,
+    OPDS2Serializer,
+)
 from palace.manager.feed.types import (
     Acquisition,
     Author,
@@ -227,3 +231,22 @@ def test_serialize_opds_message(self):
         assert OPDS2Serializer().serialize_opds_message(
             OPDSMessage("URN", 200, "Description")
         ) == dict(urn="URN", description="Description")
+
+    def test_serialize_sort_links(self):
+        feed_data = FeedData()
+        link = Link(href="test", rel="test_rel", title="text1")
+        link.add_attributes(dict(facetGroup="Sort by", activeFacet="true"))
+        feed_data.facet_links.append(link)
+        links = OPDS2Serializer()._serialize_feed_links(feed=feed_data)
+
+        assert links == {
+            "links": [
+                {
+                    "href": "test",
+                    "rel": PALACE_REL_SORT,
+                    "title": "text1",
+                    "properties": {PALACE_PROPERTIES_ACTIVE_SORT: "true"},
+                }
+            ],
+            "facets": [],
+        }

tests/manager/feed/test_opds_serializer.py

@@ -3,7 +3,8 @@
 import pytz
 from lxml import etree
 
-from palace.manager.feed.serializer.opds import OPDS1Serializer
+from palace.manager.feed.serializer.opds import OPDS1Serializer, is_sort_link
+from palace.manager.feed.serializer.opds2 import PALACE_REL_SORT
 from palace.manager.feed.types import (
     Acquisition,
     Author,
@@ -255,3 +256,17 @@ def test_serialize_opds_message(self):
         serializer = OPDS1Serializer()
         result = serializer.serialize_opds_message(message)
         assert serializer.to_string(result) == serializer.to_string(message.tag)
+
+    def test_serialize_sort_link(self):
+        link = Link(href="test", rel="test_rel", title="text1")
+        link.add_attributes(dict(facetGroup="Sort by", activeFacet="true"))
+        serializer = OPDS1Serializer()
+        assert is_sort_link(link)
+        sort_link = serializer._serialize_sort_link(link)
+        assert sort_link.attrib["title"] == "text1"
+        assert sort_link.attrib["href"] == "test"
+        assert sort_link.attrib["rel"] == PALACE_REL_SORT
+        assert (
+            sort_link.attrib["{http://palaceproject.io/terms/properties/}active-sort"]
+            == "true"
+        )