fix: strip reserved 'code' param before build() in component reuse path by aayushbaluni · Pull Request #12712 · langflow-ai/langflow

aayushbaluni · 2026-04-15T07:49:40Z

Summary

Fixes #8610 and the duplicate report at #13067.

Root cause: When a custom component is reused (self.custom_component already exists on the vertex), the else branch of Vertex._build calls get_params(self.params) and passes the result straight into build_custom_component, which calls build(**params). Unlike the instantiate_class path — which pops code before use — the reuse path leaks the synthetic code template field through to build(), raising:

TypeError: <Component>.build() got an unexpected keyword argument 'code'

for any legacy CustomComponent whose build() signature doesn't accept **kwargs (e.g. a custom MiddlewareComponent / PolicyCheck with def build(self, api_key, middleware_url, user_request)).

Modern Component subclasses use output methods and aren't affected, which is why this slipped through.

Fix

Three defensive params.pop("code", None) insertions so both code paths consistently strip the reserved code field before calling build():

src/lfx/src/lfx/graph/vertex/base.py — reuse branch of _build, right after get_params().
src/lfx/src/lfx/interface/initialize/loading.py — top of build_custom_component() (catches any other caller that forgets to strip).
src/backend/base/langflow/interface/initialize/loading.py — same defensive strip in the parallel build_custom_component() copy. In production this duplicate is dead code (only update_params_with_load_from_db_fields is imported from it via endpoints.py), but keeping it in sync avoids future drift.

Testing

New regression tests in src/lfx/tests/unit/interface/test_loading_custom_component_code_param.py covering:
- Strict sync build() signature with code in params.
- Strict async build() signature with code in params.
- code: None and missing-code variants (pop must be safe).
- get_params reuse-path semantics.
All existing test_loading.py tests still pass.

Branch

Rebased onto release-1.10.0 (was previously on main) to target the active release branch.

Notes

This PR does not address the separate "Message → str" connection-compatibility complaint from #13067's bug report; that's a frontend type-system issue with a different root cause and should be triaged separately.

Made with Cursor

Summary by CodeRabbit

Bug Fixes
- Resolved a parameter handling issue in custom component reuse that could cause incorrect values to persist across component initialization cycles.

coderabbitai · 2026-04-15T07:50:05Z

Walkthrough

This PR fixes a bug where the "code" parameter was being passed to custom component build() methods, causing TypeError. The fix removes the "code" entry at two key points in the component building pipeline before it reaches downstream build() invocations.

Changes

Cohort / File(s)	Summary
Parameter Cleanup `src/lfx/src/lfx/graph/vertex/base.py`, `src/lfx/src/lfx/interface/initialize/loading.py`	Removes the `"code"` key from params dictionaries using `pop("code", None)` before custom component building and result construction to prevent unexpected keyword argument errors.

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~3 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 adds two defensive lines to fix TypeError when reusing custom components with code parameter, but includes no regression tests to verify the fix.	Add regression tests verifying the TypeError no longer occurs when reusing custom components with the code parameter in both instantiate and reuse paths.
Out of Scope Changes check	⚠️ Warning	The PR contains only the two minimal changes needed to strip 'code' from params. However, issue `#8610` mentions a secondary problem about input/output type compatibility (Text Input to Text Field) that is not addressed here.	The PR title and objectives mention addressing issue `#8610`, which includes a secondary type compatibility problem between Text Input and Text Field that remains unresolved in these changes.
Docstring Coverage	⚠️ Warning	Docstring coverage is 50.00% 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 modifies critical async functions but includes zero new test coverage for the modified code paths.	Add async pytest test cases in test_vertex_base.py and test_loading.py to verify the code parameter removal fix and prevent regression of issue `#8610`.
Test File Naming And Structure	⚠️ Warning	PR adds 2 lines of production code to fix TypeError in MiddlewareComponent.build() but includes no new or updated test files to cover the changes.	Add test files with descriptive test cases verifying code parameter removal in both instantiate and reuse paths, ensuring components no longer receive unexpected code kwargs.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and concisely describes the main fix: removing the 'code' parameter before build() in the component reuse path, which directly addresses the core issue.
Linked Issues check	✅ Passed	The PR successfully addresses the primary requirement from issue `#8610`: preventing TypeError by removing the reserved 'code' parameter before calling build() in both component paths.
Excessive Mock Usage Warning	✅ Passed	PR includes only two source files with minimal changes (+1/-0 each) and no test files are modified or added.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.

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Verifies that TypeError no longer occurs when reusing custom components with the code parameter in both instantiate and reuse paths. Per CodeRabbit review on PR langflow-ai#12712. Made-with: Cursor

…th (langflow-ai#8610) Root cause: When a custom component is reused (self.custom_component already exists), get_params() returns params that still include the reserved 'code' field. Unlike the instantiate_class path which pops 'code' before use, the reuse path passes it through to build_custom_component, which calls build(**params) — causing TypeError for components whose build() method does not accept **kwargs. Made-with: Cursor

Verifies that TypeError no longer occurs when reusing custom components with the code parameter in both instantiate and reuse paths. Per CodeRabbit review on PR langflow-ai#12712. Made-with: Cursor

Mirror the lfx fix in the parallel src/backend/base/langflow/interface/ initialize/loading.py copy. In production this build_custom_component is dead code (only update_params_with_load_from_db_fields is imported from this module), but keeping the duplicate in sync avoids future drift and the same TypeError if any caller starts using it.

erichare

LGTM, thank you @aayushbaluni

aayushbaluni mentioned this pull request Apr 15, 2026

TypeError: MiddlewareComponent.build() got an unexpected keyword argument 'code' #8610

Closed

github-actions Bot added bug Something isn't working and removed bug Something isn't working labels Apr 15, 2026

Adam-Aghili force-pushed the main branch from fe42df7 to 9aae6de Compare April 15, 2026 20:00

aayushbaluni force-pushed the fix/8610-strip-code-from-build-params branch from c8d48e4 to 447f375 Compare April 26, 2026 06:15

github-actions Bot added bug Something isn't working and removed bug Something isn't working labels Apr 26, 2026

aayushbaluni and others added 4 commits May 11, 2026 08:46

test: add regression tests for custom component code parameter reuse

fcd58bd

Verifies that TypeError no longer occurs when reusing custom components with the code parameter in both instantiate and reuse paths. Per CodeRabbit review on PR langflow-ai#12712. Made-with: Cursor

[autofix.ci] apply automated fixes

8552920

erichare force-pushed the fix/8610-strip-code-from-build-params branch from 447f375 to e7f2597 Compare May 11, 2026 15:46

erichare changed the base branch from main to release-1.10.0 May 11, 2026 15:47

erichare mentioned this pull request May 11, 2026

fix: strip 'code' field from custom component build params #13067

Closed

4 tasks

github-actions Bot added bug Something isn't working and removed bug Something isn't working labels May 11, 2026

erichare self-requested a review May 11, 2026 15:48

erichare approved these changes May 11, 2026

View reviewed changes

erichare enabled auto-merge May 11, 2026 16:01

erichare added this pull request to the merge queue May 11, 2026

Merged via the queue into langflow-ai:release-1.10.0 with commit 5c111a1 May 11, 2026
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fix: strip reserved 'code' param before build() in component reuse path#12712

fix: strip reserved 'code' param before build() in component reuse path#12712
erichare merged 4 commits into
langflow-ai:release-1.10.0from
aayushbaluni:fix/8610-strip-code-from-build-params

aayushbaluni commented Apr 15, 2026 •

edited by erichare

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aayushbaluni commented Apr 15, 2026 • edited by erichare Loading Uh oh! There was an error while loading. Please reload this page.

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aayushbaluni commented Apr 15, 2026 •

edited by erichare

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coderabbitai Bot commented Apr 15, 2026 •

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