fix: add missing async method to Combined KB (#3412)

## Summary

The CombinedKnowledgeBase is missing the implementation for the
`async_document_lists` method.

Plus, the abstract method is not marked as `async`.


## Type of change

- [x] Bug fix
- [ ] New feature
- [ ] Breaking change
- [ ] Improvement
- [ ] Model update
- [ ] Other:

---

## Checklist

- [ ] Code complies with style guidelines
- [ ] Ran format/validation scripts (`./scripts/format.sh` and
`./scripts/validate.sh`)
- [ ] Self-review completed
- [ ] Documentation updated (comments, docstrings)
- [x] Examples and guides: Relevant cookbook examples have been included
or updated (if applicable)
- [ ] Tested in clean environment
- [ ] Tests added/updated (if applicable)

---------

Co-authored-by: Fabio Natanael Kepler <fabio@kepler.pro.br>

Author: kausmeows

cookbook/agent_concepts/knowledge/combined_kb_async.py

@@ -0,0 +1,80 @@
+import asyncio
+from pathlib import Path
+
+from agno.agent import Agent
+from agno.knowledge.combined import CombinedKnowledgeBase
+from agno.knowledge.csv import CSVKnowledgeBase
+from agno.knowledge.pdf import PDFKnowledgeBase
+from agno.knowledge.pdf_url import PDFUrlKnowledgeBase
+from agno.knowledge.website import WebsiteKnowledgeBase
+from agno.vectordb.pgvector import PgVector
+
+db_url = "postgresql+psycopg://ai:ai@localhost:5532/ai"
+
+# Create CSV knowledge base
+csv_kb = CSVKnowledgeBase(
+    path=Path("data/csvs"),
+    vector_db=PgVector(
+        table_name="csv_documents",
+        db_url=db_url,
+    ),
+)
+
+# Create PDF URL knowledge base
+pdf_url_kb = PDFUrlKnowledgeBase(
+    urls=["https://agno-public.s3.amazonaws.com/recipes/ThaiRecipes.pdf"],
+    vector_db=PgVector(
+        table_name="pdf_documents",
+        db_url=db_url,
+    ),
+)
+
+# Create Website knowledge base
+website_kb = WebsiteKnowledgeBase(
+    urls=["https://docs.agno.com/introduction"],
+    max_links=10,
+    vector_db=PgVector(
+        table_name="website_documents",
+        db_url=db_url,
+    ),
+)
+
+# Create Local PDF knowledge base
+local_pdf_kb = PDFKnowledgeBase(
+    path="data/pdfs",
+    vector_db=PgVector(
+        table_name="pdf_documents",
+        db_url=db_url,
+    ),
+)
+
+# Combine knowledge bases
+knowledge_base = CombinedKnowledgeBase(
+    sources=[
+        csv_kb,
+        pdf_url_kb,
+        website_kb,
+        local_pdf_kb,
+    ],
+    vector_db=PgVector(
+        table_name="combined_documents",
+        db_url=db_url,
+    ),
+)
+
+# Initialize the Agent with the combined knowledge base
+agent = Agent(
+    knowledge=knowledge_base,
+    search_knowledge=True,
+)
+
+if __name__ == "__main__":
+    # Comment out after first run
+    asyncio.run(knowledge_base.aload(recreate=False))
+
+    # Create and use the agent
+    asyncio.run(
+        agent.aprint_response(
+            "Ask me about something from the knowledge base", markdown=True
+        )
+    )

libs/agno/agno/knowledge/agent.py

@@ -44,7 +44,7 @@ def document_lists(self) -> Iterator[List[Document]]:
         raise NotImplementedError
 
     @property
-    def async_document_lists(self) -> AsyncIterator[List[Document]]:
+    async def async_document_lists(self) -> AsyncIterator[List[Document]]:
         """Iterator that yields lists of documents in the knowledge base
         Each object yielded by the iterator is a list of documents.
         """
@@ -167,7 +167,7 @@ async def aload(
 
         log_info("Loading knowledge base")
         num_documents = 0
-        async for document_list in self.async_document_lists:
+        async for document_list in await self.async_document_lists:
             documents_to_load = document_list
             # Track metadata for filtering capabilities
             for doc in document_list:

libs/agno/agno/knowledge/combined.py

@@ -1,4 +1,4 @@
-from typing import Iterator, List
+from typing import AsyncIterator, Iterator, List
 
 from agno.document import Document
 from agno.knowledge.agent import AgentKnowledge
@@ -20,3 +20,17 @@ def document_lists(self) -> Iterator[List[Document]]:
         for kb in self.sources:
             log_debug(f"Loading documents from {kb.__class__.__name__}")
             yield from kb.document_lists
+
+    @property
+    async def async_document_lists(self) -> AsyncIterator[List[Document]]:
+        """Iterate over knowledge bases and yield lists of documents.
+        Each object yielded by the iterator is a list of documents.
+
+        Returns:
+            Iterator[List[Document]]: Iterator yielding list of documents
+        """
+
+        for kb in self.sources:
+            log_debug(f"Loading documents from {kb.__class__.__name__}")
+            async for document in await kb.async_document_lists:
+                yield document