refactor: select in service API dataset document and segment controllers

[RenzoMXD]

Summary

• Migrate 18 db.session.query() calls to SQLAlchemy 2.0 select() style in
  controllers/service_api/dataset/document.py (9) and segment.py (9)
• Use session.scalar(select(...).where(...).limit(1)) for filtered lookups
• Use session.scalar(select(func.count(...)).where(...)) for count queries
• Update unit test mocks to match new query patterns (mock wiring only — no test
  logic or assertions changed)

Test plan

• All 366 dataset controller tests pass
• All 705 service_api tests pass
• Type-check passes (basedpyright)

Part of #22668

[github-actions]

Pyrefly Diff

No changes detected.

[github-actions]

Pyrefly Diff

base → PR

--- /tmp/pyrefly_base.txt	2026-03-25 21:35:11.623460185 +0000
+++ /tmp/pyrefly_pr.txt	2026-03-25 21:35:00.156462605 +0000
@@ -6951,7 +6951,7 @@
 ERROR Could not import `MetadataValue` from `services.entities.knowledge_entities.knowledge_entities` [missing-module-attribute]
   --> tests/unit_tests/services/dataset_metadata.py:95:5
 ERROR Cannot find module `dify_graph.model_runtime.entities.model_entities` [missing-import]
-  --> tests/unit_tests/services/dataset_service_test_helpers.py:19:1
+  --> tests/unit_tests/services/dataset_service_test_helpers.py:13:1
 ERROR Argument `str` is not assignable to parameter `indexing_technique` with type `Literal['economy', 'high_quality']` in function `services.entities.knowledge_entities.rag_pipeline_entities.KnowledgeConfiguration.__init__` [bad-argument-type]
    --> tests/unit_tests/services/dataset_service_test_helpers.py:449:28
 ERROR Argument `Literal['']` is not assignable to parameter `plan` with type `CloudPlan` in function `DocumentIndexingTaskProxyTestDataFactory.create_mock_features` [bad-argument-type]

[github-actions]

Pyrefly Diff

base → PR

--- /tmp/pyrefly_base.txt	2026-03-25 22:25:22.134986925 +0000
+++ /tmp/pyrefly_pr.txt	2026-03-25 22:25:10.747901200 +0000
@@ -6950,8 +6950,6 @@
   --> tests/unit_tests/services/auth/test_jina_auth.py:35:22
 ERROR Could not import `MetadataValue` from `services.entities.knowledge_entities.knowledge_entities` [missing-module-attribute]
   --> tests/unit_tests/services/dataset_metadata.py:95:5
-ERROR Cannot find module `dify_graph.model_runtime.entities.model_entities` [missing-import]
-  --> tests/unit_tests/services/dataset_service_test_helpers.py:19:1
 ERROR Argument `str` is not assignable to parameter `indexing_technique` with type `Literal['economy', 'high_quality']` in function `services.entities.knowledge_entities.rag_pipeline_entities.KnowledgeConfiguration.__init__` [bad-argument-type]
    --> tests/unit_tests/services/dataset_service_test_helpers.py:449:28
 ERROR Argument `Literal['']` is not assignable to parameter `plan` with type `CloudPlan` in function `DocumentIndexingTaskProxyTestDataFactory.create_mock_features` [bad-argument-type]

[github-actions]

Pyrefly Diff

base → PR

--- /tmp/pyrefly_base.txt	2026-03-25 22:27:28.082149320 +0000
+++ /tmp/pyrefly_pr.txt	2026-03-25 22:27:16.577188069 +0000
@@ -6950,8 +6950,6 @@
   --> tests/unit_tests/services/auth/test_jina_auth.py:35:22
 ERROR Could not import `MetadataValue` from `services.entities.knowledge_entities.knowledge_entities` [missing-module-attribute]
   --> tests/unit_tests/services/dataset_metadata.py:95:5
-ERROR Cannot find module `dify_graph.model_runtime.entities.model_entities` [missing-import]
-  --> tests/unit_tests/services/dataset_service_test_helpers.py:19:1
 ERROR Argument `str` is not assignable to parameter `indexing_technique` with type `Literal['economy', 'high_quality']` in function `services.entities.knowledge_entities.rag_pipeline_entities.KnowledgeConfiguration.__init__` [bad-argument-type]
    --> tests/unit_tests/services/dataset_service_test_helpers.py:449:28
 ERROR Argument `Literal['']` is not assignable to parameter `plan` with type `CloudPlan` in function `DocumentIndexingTaskProxyTestDataFactory.create_mock_features` [bad-argument-type]

[github-actions]

Pyrefly Diff

No changes detected.

[github-actions]

Pyrefly Diff

base → PR

--- /tmp/pyrefly_base.txt	2026-03-26 01:05:20.686806883 +0000
+++ /tmp/pyrefly_pr.txt	2026-03-26 01:05:10.319861696 +0000
@@ -6951,7 +6951,7 @@
 ERROR Could not import `MetadataValue` from `services.entities.knowledge_entities.knowledge_entities` [missing-module-attribute]
   --> tests/unit_tests/services/dataset_metadata.py:95:5
 ERROR Cannot find module `dify_graph.model_runtime.entities.model_entities` [missing-import]
-  --> tests/unit_tests/services/dataset_service_test_helpers.py:19:1
+  --> tests/unit_tests/services/dataset_service_test_helpers.py:13:1
 ERROR Argument `str` is not assignable to parameter `indexing_technique` with type `Literal['economy', 'high_quality']` in function `services.entities.knowledge_entities.rag_pipeline_entities.KnowledgeConfiguration.__init__` [bad-argument-type]
    --> tests/unit_tests/services/dataset_service_test_helpers.py:449:28
 ERROR Argument `Literal['']` is not assignable to parameter `plan` with type `CloudPlan` in function `DocumentIndexingTaskProxyTestDataFactory.create_mock_features` [bad-argument-type]

[RenzoMXD]

@asukaminato0721 These failures are not from my code change. Please review. Thanks.

[RenzoMXD]

thanks.