Implement a rel="search" link for related entities (WIP)

cubicweb_jsonschema/views/link.py

@@ -21,6 +21,7 @@
 """
 
 
+from cubicweb import neg_role
 from cubicweb.appobject import AppObject
 from cubicweb.predicates import (
     has_permission,
@@ -188,3 +189,32 @@
         ldo['targetSchema']['$ref'] = request.resource_path(
             resource, 'schema', query={'role': VIEW_ROLE})
         return ldo
+
+
+class SearchRelatedLink(EntityLink):
+    __regid__ = 'jsonschema.search'
+    __select__ = EntityLink.__select__ & match_kwargs('rtype', 'role')
+
+    def description_object(self, resource):
+        request = resource.request
+        entity = resource.__parent__.rset.one()
+        rschema = entity.e_schema.rdef(resource.rtype, resource.role)
+        target_type = getattr(rschema, neg_role(resource.role))
+        mapper = self._cw.vreg['mappers'].select(
+            'jsonschema.entity', self._cw, etype=target_type,
+            rtype=resource.rtype, role=resource.role,
+            target_types={entity.cw_etype},
+        )
+        search_terms = mapper.json_schema(VIEW_ROLE)['properties']
+        href = (
+            request.resource_path(resource)
+            + '?searchBy=' + ','.join(
+                '%s:{%s}' % (p, p) for p in search_terms)
+        )
+        return {
+            'rel': 'search',
+            'href': href,
+            'hrefSchema': {
+                'properties': search_terms,
+            },
+        }

test/hypermedia-walkthrough.rst

@@ -571,6 +571,18 @@
           "submissionSchema": {
             "$ref": "/book/.../topics/schema?role=creation"
           }
+        },
+        {
+          "rel": "search",
+          "href": "/book/.../topics/?searchBy=name:{name}",
+          "hrefSchema": {
+            "properties": {
+              "name": {
+                "type": "string",
+                "title": "name"
+              }
+            }
+          }
         }
       ]
     }