feat: Add the support for returning struct_data.uri in DiscoveryEngineSearchTool

For https://github.com/google/adk-python/issues/3146

PiperOrigin-RevId: 818458080

src/google/adk/tools/discovery_engine_search_tool.py

@@ -80,7 +80,7 @@ class DiscoveryEngineSearchTool(FunctionTool):
       self,
       query: str,
   ) -> dict[str, Any]:
-    """Search the discovery engine.
+    """Search through Vertex AI Search's discovery engine search API.
 
     Args:
       query: The search query.
@@ -113,12 +113,22 @@ class DiscoveryEngineSearchTool(FunctionTool):
       response = self._discovery_engine_client.search(request)
       for item in response.results:
         chunk = item.chunk
-        if not chunk or not chunk.document_metadata:
+        if not chunk:
           continue
 
+        title = ""
+        uri = ""
+        doc_metadata = chunk.document_metadata
+        if doc_metadata:
+          title = doc_metadata.title
+          uri = doc_metadata.uri
+          # Prioritize URI from struct_data if it exists.
+          if doc_metadata.struct_data and "uri" in doc_metadata.struct_data:
+            uri = doc_metadata.struct_data["uri"]
+
         results.append({
-            "title": chunk.document_metadata.title,
-            "url": chunk.document_metadata.uri,
+            "title": title,
+            "url": uri,
             "content": chunk.content,
         })
     except GoogleAPICallError as e:

tests/unittests/tools/test_discovery_engine_search_tool.py

@@ -87,7 +87,11 @@ class TestDiscoveryEngineSearchTool:
             chunk=discoveryengine.Chunk(
                 document_metadata={
                     "title": "Test Title",
-                    "uri": "http://example.com",
+                    "uri": "gs://test_bucket/test_file",
+                    "struct_data": {
+                        "key1": "value1",
+                        "uri": "http://example.com",
+                    },
                 },
                 content="Test Content",
             )