From 2fe8dbd7ca77cc1d429d5c1d06c1124b0ee95189 Mon Sep 17 00:00:00 2001
From: wangxiaolei <fatelei@gmail.com>
Date: Thu, 28 May 2026 15:31:36 +0800
Subject: [PATCH] fix: fix cannot extract elements from a scalar (#36769)

---
 .../console/datasets/datasets_segments.py     | 15 ++++---
 .../datasets/test_datasets_segments.py        | 42 +++++++++++++++++++
 2 files changed, 52 insertions(+), 5 deletions(-)

diff --git a/api/controllers/console/datasets/datasets_segments.py b/api/controllers/console/datasets/datasets_segments.py
index df359938de..e98878db4e 100644
--- a/api/controllers/console/datasets/datasets_segments.py
+++ b/api/controllers/console/datasets/datasets_segments.py
@@ -3,7 +3,7 @@ import uuid
 from flask import request
 from flask_restx import Resource, marshal
 from pydantic import BaseModel, Field
-from sqlalchemy import String, cast, func, or_, select
+from sqlalchemy import String, case, cast, func, literal, or_, select
 from sqlalchemy.dialects.postgresql import JSONB
 from werkzeug.exceptions import Forbidden, NotFound
 
@@ -159,12 +159,17 @@ class DatasetDocumentSegmentListApi(Resource):
             # Use database-specific methods for JSON array search
             if dify_config.SQLALCHEMY_DATABASE_URI_SCHEME == "postgresql":
                 # PostgreSQL: Use jsonb_array_elements_text to properly handle Unicode/Chinese text
-                # Guard with jsonb_typeof to avoid "cannot extract elements from a scalar" error
-                # when keywords is null or a non-array JSON value.
+                # Feed the set-returning function a JSON array in every row. Filtering in
+                # the subquery is not enough because PostgreSQL can still evaluate the
+                # SRF on scalar JSON before applying the predicate.
+                keywords_jsonb = cast(DocumentSegment.keywords, JSONB)
+                keywords_array = case(
+                    (func.jsonb_typeof(keywords_jsonb) == "array", keywords_jsonb),
+                    else_=cast(literal("[]"), JSONB),
+                )
                 keywords_condition = func.array_to_string(
                     func.array(
-                        select(func.jsonb_array_elements_text(cast(DocumentSegment.keywords, JSONB)))
-                        .where(func.jsonb_typeof(cast(DocumentSegment.keywords, JSONB)) == "array")
+                        select(func.jsonb_array_elements_text(keywords_array))
                         .correlate(DocumentSegment)
                         .scalar_subquery()
                     ),
diff --git a/api/tests/unit_tests/controllers/console/datasets/test_datasets_segments.py b/api/tests/unit_tests/controllers/console/datasets/test_datasets_segments.py
index 66d257ee66..c89ac69b68 100644
--- a/api/tests/unit_tests/controllers/console/datasets/test_datasets_segments.py
+++ b/api/tests/unit_tests/controllers/console/datasets/test_datasets_segments.py
@@ -1036,6 +1036,48 @@ class TestSegmentListAdvancedCases:
         assert status == 200
         assert response["total"] == 1
 
+    def test_segment_list_postgres_keyword_filter_handles_scalar_keywords(self, app: Flask):
+        api = DatasetDocumentSegmentListApi()
+        method = unwrap(api.get)
+
+        dataset = MagicMock()
+        document = MagicMock()
+        pagination = MagicMock(items=[], total=0, pages=0)
+
+        with (
+            app.test_request_context("/?keyword=test"),
+            patch(
+                "controllers.console.datasets.datasets_segments.current_account_with_tenant",
+                return_value=(MagicMock(), "11111111-1111-1111-1111-111111111111"),
+            ),
+            patch(
+                "controllers.console.datasets.datasets_segments.DatasetService.get_dataset",
+                return_value=dataset,
+            ),
+            patch(
+                "controllers.console.datasets.datasets_segments.DatasetService.check_dataset_permission",
+                return_value=None,
+            ),
+            patch(
+                "controllers.console.datasets.datasets_segments.DocumentService.get_document",
+                return_value=document,
+            ),
+            patch(
+                "controllers.console.datasets.datasets_segments.dify_config",
+                SimpleNamespace(SQLALCHEMY_DATABASE_URI_SCHEME="postgresql"),
+            ),
+            patch(
+                "controllers.console.datasets.datasets_segments.db.paginate",
+                return_value=pagination,
+            ) as paginate_mock,
+        ):
+            method(api, "22222222-2222-2222-2222-222222222222", "33333333-3333-3333-3333-333333333333")
+
+        query = paginate_mock.call_args.kwargs["select"]
+        sql = str(query.compile(compile_kwargs={"literal_binds": True}))
+        assert "jsonb_array_elements_text(CASE" in sql
+        assert "ELSE CAST('[]' AS JSONB)" in sql
+
     def test_segment_list_permission_denied(self, app: Flask):
         """Test segment list with permission denied"""
         api = DatasetDocumentSegmentListApi()