fix: add ON DELETE CASCADE to span.trace_id foreign key by xr843 · Pull Request #12384 · langflow-ai/langflow

xr843 · 2026-03-29T00:24:27Z

Summary

Adds Alembic migration to drop and re-create the span.trace_id FK with ON DELETE CASCADE, completing the cascade chain flow → trace → span at the database level
Updates SpanTable model to include ondelete="CASCADE" on trace_id field so new deployments get the correct schema
Adds explicit DELETE for SpanTable and TraceTable in cascade_delete_flow() for defence in depth, matching the existing pattern for MessageTable, TransactionTable, VertexBuildTable, and FlowVersion

Details

The original migration 3478f0bd6ccb created the span.trace_id FK without ondelete="CASCADE". When PostgreSQL cascades a flow deletion through flow → trace (which correctly has CASCADE), it then tries to delete trace rows but fails because span rows still reference them without a cascade rule.

Changes

File	Change
`alembic/versions/83cd04b12a34_add_ondelete_cascade_to_span_trace_id_fk.py`	New migration: drops existing FK, re-creates with `ON DELETE CASCADE`
`services/database/models/traces/model.py`	Added `ondelete="CASCADE"` to `SpanTable.trace_id` Field
`api/utils/core.py`	Added explicit span/trace deletion in `cascade_delete_flow()`

Migration safety

Uses batch_alter_table for SQLite compatibility
Guards with table_exists check
Introspects actual FK constraint name (handles both auto-generated and named constraints)
Fully reversible downgrade() function
Follows the exact same pattern as existing cascade migrations (0e6138e7a0c2, 59a272d6669a)

Test plan

Run migration against PostgreSQL: alembic upgrade head
Run migration against SQLite: alembic upgrade head
Create a flow, execute it to generate traces/spans, then delete the flow — should succeed without ForeignKeyViolation
Run alembic downgrade -1 to verify reversibility
Verify existing flows without traces can still be deleted

🤖 Generated with Claude Code

Summary by CodeRabbit

Bug Fixes
- Improved data consistency by implementing cascade deletion for trace and span records to ensure proper cleanup and prevent orphaned data when flows are deleted.
Chores
- Updated package dependencies for improved stability and compatibility.

Flow deletion fails with ForeignKeyViolation when traces exist because the span.trace_id FK was created without ON DELETE CASCADE, breaking the cascade chain flow -> trace -> span. This commit: - Adds an Alembic migration to drop and re-create the span.trace_id FK with ON DELETE CASCADE (database-level fix) - Updates the SpanTable model to include ondelete="CASCADE" on trace_id - Adds explicit delete of SpanTable and TraceTable in cascade_delete_flow for defence in depth (matches existing pattern for other child tables) Fixes langflow-ai#12346 Co-Authored-By: Claude Opus 4.6 (1M context) <[email protected]>

coderabbitai · 2026-03-29T00:24:54Z

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Walkthrough

This pull request fixes a foreign key constraint violation that occurs when deleting flows with associated execution traces. The fix applies both database-level changes (adding ON DELETE CASCADE to the span.trace_id foreign key constraint via migration and ORM model update) and application-level changes (explicit deletion of spans and traces in the cascade_delete_flow function).

Changes

Cohort / File(s)	Summary
Database Schema Migration `src/backend/base/langflow/alembic/versions/83cd04b12a34_add_ondelete_cascade_to_span_trace_id_fk.py`	New Alembic migration that adds `ON DELETE CASCADE` to the `span.trace_id` foreign key constraint. Upgrade path checks for existing FK and recreates it with cascade behavior; downgrade path removes cascade configuration and lets the database auto-generate the constraint name.
Cascade Deletion Logic `src/backend/base/langflow/api/utils/core.py`	Modified `cascade_delete_flow` function to explicitly delete `SpanTable` and `TraceTable` records before deleting parent `Flow` records, ensuring proper deletion order and preventing foreign key constraint violations.
ORM Model Configuration `src/backend/base/langflow/services/database/models/traces/model.py`	Updated `SpanTable.trace_id` field definition to include `ondelete="CASCADE"` parameter in the `Field()` declaration, aligning ORM-level cascade configuration with the database-level constraint.
Dependency Updates `src/lfx/src/lfx/_assets/component_index.json`	Updated `google` package dependency versions from `2.30.0` to `2.8.0` across multiple component entries; updated corresponding SHA256 checksum.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~22 minutes

Important

Pre-merge checks failed

Please resolve all errors before merging. Addressing warnings is optional.

❌ Failed checks (1 error, 4 warnings)

Check name	Status	Explanation	Resolution
Test Coverage For New Implementations	❌ Error	PR modifies critical database cascade logic but includes no automated test files for migration execution, cascade_delete_flow behavior, or foreign key cascade validation.	Add test files: migration test (test_migration_83cd04b12a34.py) and cascade_delete_flow tests verifying proper deletion of traces/spans and no ForeignKeyViolation errors on both database backends.
Out of Scope Changes check	⚠️ Warning	The PR includes an out-of-scope change: component_index.json was updated with Google package version downgrade (2.30.0 to 2.8.0) and SHA256 hash, which is unrelated to the span.trace_id cascade deletion fix.	Remove the component_index.json changes from this PR as they are unrelated to the cascade deletion fix, or address them in a separate PR with appropriate context.
Docstring Coverage	⚠️ Warning	Docstring coverage is 25.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.
Test Quality And Coverage	⚠️ Warning	PR lacks test coverage for application-level cascade_delete_flow() changes and end-to-end flow deletion with trace/span data.	Add tests for cascade_delete_flow() function with trace/span data and end-to-end test of flow deletion API with actual cascade delete chain.
Test File Naming And Structure	⚠️ Warning	No test files were added to verify the cascade deletion functionality or Alembic migration changes.	Add test files following pytest naming conventions to verify cascade_delete_flow function and migration upgrade/downgrade functionality.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately summarizes the main change: adding ON DELETE CASCADE to the span.trace_id foreign key to fix a ForeignKeyViolation bug, which is the primary objective of this PR.
Linked Issues check	✅ Passed	All coding objectives from issue `#12346` are met: the migration alters the span.trace_id FK with ON DELETE CASCADE for database-level robustness, the SpanTable model is updated with ondelete="CASCADE", and cascade_delete_flow explicitly deletes SpanTable and TraceTable for application-level safety.
Excessive Mock Usage Warning	✅ Passed	The PR does not include any test files, so mock usage cannot be assessed.

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xr843 · 2026-03-30T05:12:51Z

CI Failure Analysis

All three CI failures are unrelated to this PR's changes:

1. Ruff Style Check (PERF403) — `setup.py:68`

Pre-existing issue on main. The failing file (src/backend/base/langflow/initial_setup/setup.py) is not modified by this PR. The same Ruff Style Check workflow also fails on main.

2. Test Docker Images — Node.js download failure

The Docker build fails during Node.js installation (npm install -g npm@latest exit code 1). This is an infrastructure/networking issue in the Docker build, unrelated to our database migration or Python code changes.

3. validate-migration — "Resource not accessible by integration"

This is a known GitHub Actions permissions limitation for fork PRs. The workflow actually validated the migration successfully (the log shows ✅ Migration Validation Passed — All migrations follow the Expand-Contract pattern correctly), but it cannot post the status comment back to the PR due to restricted token permissions on fork PRs.

Passing checks relevant to this PR

✅ Mypy (3.10, 3.11, 3.12, 3.13) — all pass
✅ Run Ruff Check and Format — passes (separate from Ruff Style Check)
✅ Backend Unit Tests & Integration Tests
✅ Frontend Tests
✅ Update Component Index / Starter Projects

xr843 · 2026-03-30T08:19:04Z

Hi maintainers, the Ruff Style Check failure is not related to this PR.

The error is a pre-existing PERF403 violation in src/backend/base/langflow/initial_setup/setup.py:68, which is not a file modified by this PR. The same violation exists on the main branch.

Happy to rebase once this is resolved upstream!

github-actions bot added the community Pull Request from an external contributor label Mar 29, 2026

github-actions bot added the bug Something isn't working label Mar 29, 2026

[autofix.ci] apply automated fixes

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github-actions bot added bug Something isn't working and removed bug Something isn't working labels Mar 29, 2026

[autofix.ci] apply automated fixes (attempt 2/3)

919b84d

github-actions bot added bug Something isn't working and removed bug Something isn't working labels Mar 29, 2026

fix: correct mypy type-ignore comment (attr-defined, not union-attr)

eed39d9

github-actions bot added bug Something isn't working and removed bug Something isn't working labels Mar 30, 2026

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fix: add ON DELETE CASCADE to span.trace_id foreign key#12384

fix: add ON DELETE CASCADE to span.trace_id foreign key#12384
xr843 wants to merge 4 commits intolangflow-ai:mainfrom
xr843:fix/flow-deletion-fk-cascade

xr843 commented Mar 29, 2026 •

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Summary

Details

Changes

Migration safety

Test plan

Summary by CodeRabbit

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❌ Failed checks (1 error, 4 warnings)

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xr843 commented Mar 30, 2026

CI Failure Analysis

1. Ruff Style Check (PERF403) — setup.py:68

2. Test Docker Images — Node.js download failure

3. validate-migration — "Resource not accessible by integration"

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xr843 commented Mar 30, 2026

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xr843 commented Mar 29, 2026 •

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1. Ruff Style Check (PERF403) — `setup.py:68`