from llama_index.core.vector_stores import ( MetadataFilter, MetadataFilters, FilterOperator, ) filters = MetadataFilters( filters=[ MetadataFilter(key="theme", operator=FilterOperator.EQ, value="Mafia"), ] ) retriever = index.as_retriever(filters=filters) retriever.retrieve("...") query_engine = index.as_query_engine(filters=filters) query_engine.query(...)