Re-introduce LazyCatalogResultSerializer with batching logic:

The LazyCatalogResultSerializer has been removed in #99 without
a pressing need to do so. Therefore we re-introduce it here and
make it handle the batching logic that was previously left to
the SearchHandler.

src/plone/restapi/search/handler.py

@@ -1,7 +1,5 @@
 # -*- coding: utf-8 -*-
-from plone.restapi.batching import HypermediaBatch
 from plone.restapi.interfaces import ISerializeToJson
-from plone.restapi.interfaces import ISerializeToJsonSummary
 from plone.restapi.interfaces import IZCatalogCompatibleQuery
 from Products.CMFCore.utils import getToolByName
 from zope.component import getMultiAdapter
@@ -40,29 +38,9 @@ def search(self, query=None):
         query = self._parse_query(query)
         self._constrain_query_by_path(query)
 
-        catalog = getToolByName(self.context, 'portal_catalog')
-        brains = catalog(query)
-
-        batch = HypermediaBatch(self.context, self.request, brains)
-
-        results = {}
-        results['@id'] = batch.canonical_url
-        results['items_total'] = batch.items_total
-        if batch.links:
-            results['batching'] = batch.links
-
-        results['items'] = []
-        for brain in batch:
-            result = getMultiAdapter(
-                (brain, self.request), ISerializeToJsonSummary)()
-
-            if metadata_fields:
-                # Merge additional metadata into the summary we already have
-                metadata = getMultiAdapter(
-                    (brain, self.request),
-                    ISerializeToJson)(metadata_fields=metadata_fields)
-                result.update(metadata)
-
-            results['items'].append(result)
+        lazy_resultset = self.catalog.searchResults(query)
+        results = getMultiAdapter(
+            (lazy_resultset, self.request),
+            ISerializeToJson)(metadata_fields=metadata_fields)
 
         return results

src/plone/restapi/serializer/catalog.py

@@ -1,9 +1,11 @@
 # -*- coding: utf-8 -*-
+from plone.restapi.batching import HypermediaBatch
 from plone.restapi.interfaces import ISerializeToJson
 from plone.restapi.interfaces import ISerializeToJsonSummary
 from plone.restapi.serializer.converters import json_compatible
 from Products.CMFCore.utils import getToolByName
 from Products.ZCatalog.interfaces import ICatalogBrain
+from Products.ZCatalog.Lazy import Lazy
 from zope.component import adapter
 from zope.component import getMultiAdapter
 from zope.component.hooks import getSite
@@ -56,3 +58,40 @@ def __call__(self, metadata_fields=('_all',)):
             result[attr] = value
 
         return result
+
+
+@implementer(ISerializeToJson)
+@adapter(Lazy, Interface)
+class LazyCatalogResultSerializer(object):
+    """Serializes a ZCatalog resultset (one of the subclasses of `Lazy`) to
+    a Python data structure that can in turn be serialized to JSON.
+    """
+
+    def __init__(self, lazy_resultset, request):
+        self.lazy_resultset = lazy_resultset
+        self.request = request
+
+    def __call__(self, metadata_fields=()):
+        batch = HypermediaBatch(self.request, self.lazy_resultset)
+
+        results = {}
+        results['@id'] = batch.canonical_url
+        results['items_total'] = batch.items_total
+        if batch.links:
+            results['batching'] = batch.links
+
+        results['items'] = []
+        for brain in batch:
+            result = getMultiAdapter(
+                (brain, self.request), ISerializeToJsonSummary)()
+
+            if metadata_fields:
+                # Merge additional metadata into the summary we already have
+                metadata = getMultiAdapter(
+                    (brain, self.request),
+                    ISerializeToJson)(metadata_fields=metadata_fields)
+                result.update(metadata)
+
+            results['items'].append(result)
+
+        return results

src/plone/restapi/serializer/configure.zcml

@@ -55,5 +55,6 @@
     </configure>
 
     <adapter factory=".catalog.BrainSerializer" />
+    <adapter factory=".catalog.LazyCatalogResultSerializer" />
 
 </configure>

src/plone/restapi/tests/test_serializer_catalog.py

@@ -35,6 +35,24 @@ def setUp(self):
         IMutableUUID(self.doc).set('77779ffa110e45afb1ba502f75f77777')
         self.doc.reindexObject()
 
+    def test_lazy_cat_serialization_empty_resultset(self):
+        # Force an empty resultset (Products.ZCatalog.Lazy.LazyCat)
+        lazy_cat = self.catalog(path='doesnt-exist')
+        results = getMultiAdapter((lazy_cat, self.request), ISerializeToJson)()
+
+        self.assertDictEqual(
+            {'@id': 'http://nohost', 'items': [], 'items_total': 0},
+            results)
+
+    def test_lazy_map_serialization(self):
+        # Test serialization of a Products.ZCatalog.Lazy.LazyMap
+        lazy_map = self.catalog()
+        results = getMultiAdapter((lazy_map, self.request), ISerializeToJson)()
+
+        self.assertDictContainsSubset({'@id': 'http://nohost'}, results)
+        self.assertDictContainsSubset({'items_total': 2}, results)
+        self.assertEqual(2, len(results['items']))
+
     def test_brain_summary_representation(self):
         lazy_map = self.catalog(path='/plone/my-folder/my-document')
         brain = lazy_map[0]