fix(query): accept a bare string for include_vector

test/collection/test_include_vector_str.py

@@ -0,0 +1,32 @@
+"""`include_vector` accepts a bare ``str`` but then requests no vector at all.
+
+``INCLUDE_VECTOR = Union[bool, str, List[str]]`` and ``_parse_return_metadata``
+validates ``[bool, str, Sequence]``, so a single named vector may be passed as a
+string. ``_MetadataQuery.from_public`` only handles ``bool`` and ``list``, so a
+string falls through both branches and the gRPC ``MetadataRequest`` asks for
+nothing, while ``_QueryOptions`` still reports ``include_vector=True``.
+"""
+
+from weaviate.collections.classes.grpc import _MetadataQuery
+from weaviate.collections.classes.internal import _QueryOptions
+
+
+def test_metadata_query_from_public_with_a_list() -> None:
+    """Baseline: the list form requests the named vector."""
+    md = _MetadataQuery.from_public(None, ["named_vec"])
+    assert md.vectors == ["named_vec"]
+
+
+def test_metadata_query_from_public_with_a_bare_string() -> None:
+    md = _MetadataQuery.from_public(None, "named_vec")
+    assert md.vectors == ["named_vec"], (
+        f"a bare str requested nothing: vector={md.vector!r} vectors={md.vectors!r}"
+    )
+
+
+def test_query_options_and_metadata_query_agree_for_a_bare_string() -> None:
+    """The parser is told a vector is coming; the request never asked for one."""
+    opts = _QueryOptions.from_input(None, None, "named_vec", None, None)
+    md = _MetadataQuery.from_public(None, "named_vec")
+    assert opts.include_vector is True
+    assert bool(md.vector) or md.vectors, "include_vector=True but nothing was requested"

weaviate/collections/classes/grpc.py

@@ -148,6 +148,11 @@ class _MetadataQuery:
     def from_public(
         cls, public: Optional[MetadataQuery], include_vector: INCLUDE_VECTOR
     ) -> "_MetadataQuery":
+        # INCLUDE_VECTOR permits a bare `str` for a single named vector, and the branches below
+        # test only for `bool` and `list`. Without this a `str` matched neither, so the request
+        # asked for no vector at all and the caller got none back, with no error.
+        if isinstance(include_vector, str):
+            include_vector = [include_vector]
         return (
             cls(
                 vector=include_vector if isinstance(include_vector, bool) else False,