feat: search_field should be optional in hybrid text search (docarray…

…#1516)

Signed-off-by: AnneY <evangeline-lun@foxmail.com>

docarray/index/backends/weaviate.py

@@ -891,18 +891,23 @@ def filter_batched(self, filters) -> Any:
 
             return self
 
-        def text_search(self, query, search_field) -> Any:
+        def text_search(self, query: str, search_field: Optional[str] = None) -> Any:
+
             """Find documents in the index based on a text search query
 
             :param query: The text to search for
             :param search_field: name of the field to search on
             :return: self
             """
-            bm25 = {"query": query, "properties": [search_field]}
+            bm25: Dict[str, Any] = {"query": query}
+            if search_field:
+                bm25["properties"] = [search_field]
             self._queries[0] = self._queries[0].with_bm25(**bm25)
             return self
 
-        def text_search_batched(self, queries, search_field) -> Any:
+        def text_search_batched(
+            self, queries: Sequence[str], search_field: Optional[str] = None
+        ) -> Any:
             """Find documents in the index based on a text search query
 
             :param queries: The texts to search for
@@ -915,7 +920,9 @@ def text_search_batched(self, queries, search_field) -> Any:
             new_queries = []
 
             for query, clause in zip(adj_queries, adj_clauses):
-                bm25 = {"query": clause, "properties": [search_field]}
+                bm25 = {"query": clause}
+                if search_field:
+                    bm25["properties"] = [search_field]
                 new_queries.append(query.with_bm25(**bm25))
 
             self._queries = new_queries

docs/user_guide/storing/index_weaviate.md

@@ -287,6 +287,7 @@ from docarray import BaseDoc
 from docarray.typing import NdArray
 from docarray.index.backends.weaviate import WeaviateDocumentIndex
 
+
 # Define a document schema
 class Document(BaseDoc):
     text: str
@@ -376,15 +377,7 @@ This will perform a hybrid search for the word "hello" and the vector [1, 2] and
 **Note**: Hybrid search searches through the object vector and all fields. Accordingly, the `search_field` keyword it will have no effect. 
 
 ```python
-q = (
-    store.build_query()
-    .text_search(
-        "world", search_field=None  # Set as None as it is required but has no effect
-    )
-    .find([1, 2])
-    .limit(2)
-    .build()
-)
+q = store.build_query().text_search("world").find([1, 2]).limit(2).build()
 
 docs = store.execute_query(q)
 docs

tests/index/weaviate/test_index_get_del_weaviate.py

@@ -355,7 +355,7 @@ def test_hybrid_query(test_index):
     q = (
         test_index.build_query()
         .find(query=query_embedding)
-        .text_search(query=query_text, search_field="text")
+        .text_search(query=query_text)
         .filter(where_filter)
         .build()
     )
@@ -373,7 +373,7 @@ def test_hybrid_query_batched(test_index):
         .find_batched(
             queries=query_embeddings, score_name="certainty", score_threshold=0.99
         )
-        .text_search_batched(queries=query_texts, search_field="text")
+        .text_search_batched(queries=query_texts)
         .build()
     )